diff --git a/libs/ysig/dumper.cpp b/libs/ysig/dumper.cpp
index 596a9d34..b605f6e4 100644
--- a/libs/ysig/dumper.cpp
+++ b/libs/ysig/dumper.cpp
@@ -211,20 +211,20 @@ bool SignallingDumpable::setDumper(const String& name, bool create, bool append)
 
 bool SignallingDumpable::control(NamedList& params, SignallingComponent* owner)
 {
-    String* tmp = params.getParam("operation");
-    if (!(tmp && (*tmp == "sigdump")))
+    String* tmp = params.getParam(YSTRING("operation"));
+    if (!(tmp && (*tmp == YSTRING("sigdump"))))
 	return false;
-    tmp = params.getParam("component");
+    tmp = params.getParam(YSTRING("component"));
     if (tmp && *tmp && owner && (owner->toString() != *tmp))
 	return false;
-    tmp = params.getParam("completion");
+    tmp = params.getParam(YSTRING("completion"));
     if (tmp) {
 	if (!owner)
 	    return false;
-	String part = params.getValue("partword");
+	String part = params.getValue(YSTRING("partword"));
 	return Module::itemComplete(*tmp,owner->toString(),part);
     }
-    tmp = params.getParam("file");
+    tmp = params.getParam(YSTRING("file"));
     if (tmp)
 	return setDumper(*tmp);
     return false;
diff --git a/libs/ysig/engine.cpp b/libs/ysig/engine.cpp
index e04bff0a..ae2e2cfe 100644
--- a/libs/ysig/engine.cpp
+++ b/libs/ysig/engine.cpp
@@ -92,21 +92,21 @@ SignallingComponent* SignallingFactory::build(const String& type, const NamedLis
     lock.drop();
     DDebug(DebugInfo,"Factory creating default '%s' named '%s'",type.c_str(),name->c_str());
     // now build some objects we know about
-    if (type == "SS7MTP2")
+    if (type == YSTRING("SS7MTP2"))
 	return new SS7MTP2(*name);
-    else if (type == "SS7M2PA")
+    else if (type == YSTRING("SS7M2PA"))
 	return new SS7M2PA(*name);
-    else if (type == "SS7MTP3")
+    else if (type == YSTRING("SS7MTP3"))
 	return new SS7MTP3(*name);
-    else if (type == "SS7Router")
+    else if (type == YSTRING("SS7Router"))
 	return new SS7Router(*name);
-    else if (type == "SS7Management")
+    else if (type == YSTRING("SS7Management"))
 	return new SS7Management(*name);
-    else if (type == "ISDNQ921")
+    else if (type == YSTRING("ISDNQ921"))
 	return new ISDNQ921(*name,*name);
-    else if (type == "ISDNQ931")
+    else if (type == YSTRING("ISDNQ931"))
 	return new ISDNQ931(*name,*name);
-    else if (type == "ISDNQ931Monitor")
+    else if (type == YSTRING("ISDNQ931Monitor"))
 	return new ISDNQ931Monitor(*name,*name);
     Debug(DebugMild,"Factory could not create '%s' named '%s'",type.c_str(),name->c_str());
     return 0;
@@ -132,9 +132,9 @@ SignallingComponent::SignallingComponent(const char* name, const NamedList* para
     : m_engine(0), m_compType("unknown")
 {
     if (params) {
-	name = params->getValue("debugname",name);
-	m_compType = params->getValue("type",m_compType);
-	debugLevel(params->getIntValue("debuglevel",-1));
+	name = params->getValue(YSTRING("debugname"),name);
+	m_compType = params->getValue(YSTRING("type"),m_compType);
+	debugLevel(params->getIntValue(YSTRING("debuglevel"),-1));
     }
     DDebug(engine(),DebugAll,"Component '%s' created [%p]",name,this);
     setName(name);
diff --git a/libs/ysig/isup.cpp b/libs/ysig/isup.cpp
index 70493ead..d0b70697 100644
--- a/libs/ysig/isup.cpp
+++ b/libs/ysig/isup.cpp
@@ -2062,7 +2062,7 @@ static void getMsgCompat(SS7MsgISUP* msg, bool& release, bool& cnf)
 {
     if (!msg)
 	return;
-    String* msgCompat = msg->params().getParam("MessageCompatInformation");
+    String* msgCompat = msg->params().getParam(YSTRING("MessageCompatInformation"));
     if (msgCompat) {
 	ObjList* l = msgCompat->split(',',false);
 	// Use a while() to make sure the list is destroyed
@@ -2209,7 +2209,7 @@ SignallingEvent* SS7ISUPCall::getEvent(const Time& when)
 	}
 	// Process received messages
 	msg = static_cast<SS7MsgISUP*>(dequeue());
-	if (msg && validMsgState(false,msg->type(),(msg->params().getParam("BackwardCallIndicators") != 0)))
+	if (msg && validMsgState(false,msg->type(),(msg->params().getParam(YSTRING("BackwardCallIndicators")) != 0)))
 	    switch (msg->type()) {
 		case SS7MsgISUP::IAM:
 		case SS7MsgISUP::CCR:
@@ -2237,7 +2237,7 @@ SignallingEvent* SS7ISUPCall::getEvent(const Time& when)
 		    break;
 		case SS7MsgISUP::SAM:
 		    setOverlapped(isCalledIncomplete(msg->params(),"SubsequentNumber"));
-		    msg->params().addParam("tone",msg->params().getValue("SubsequentNumber"));
+		    msg->params().addParam("tone",msg->params().getValue(YSTRING("SubsequentNumber")));
 		    msg->params().addParam("dialing",String::boolText(true));
 		    m_lastEvent = new SignallingEvent(SignallingEvent::Info,msg,this);
 		    break;
@@ -2380,7 +2380,7 @@ bool SS7ISUPCall::sendEvent(SignallingEvent* event)
 		setOverlapped(isCalledIncomplete(m_iamMsg->params()));
 		if (m_overlap) {
 		    // Check for maximum number of digits allowed
-		    String* called = m_iamMsg->params().getParam("CalledPartyNumber");
+		    String* called = m_iamMsg->params().getParam(YSTRING("CalledPartyNumber"));
 		    if (called && called->length() > isup()->m_maxCalledDigits) {
 			m_samDigits = called->substr(isup()->m_maxCalledDigits);
 			*called = called->substr(0,isup()->m_maxCalledDigits);
@@ -2398,7 +2398,7 @@ bool SS7ISUPCall::sendEvent(SignallingEvent* event)
 		if (event->message()) {
 		    copyUpper(m->params(),event->message()->params());
 		    m_inbandAvailable = m_inbandAvailable ||
-			event->message()->params().getBoolValue("earlymedia");
+			event->message()->params().getBoolValue(YSTRING("earlymedia"));
 		}
 		if (m_inbandAvailable)
 		    SignallingUtils::appendFlag(m->params(),"OptionalBackwardCallIndicators","inband");
@@ -2413,7 +2413,7 @@ bool SS7ISUPCall::sendEvent(SignallingEvent* event)
 		if (event->message()) {
 		    copyUpper(m->params(),event->message()->params());
 		    m_inbandAvailable = m_inbandAvailable ||
-			event->message()->params().getBoolValue("earlymedia");
+			event->message()->params().getBoolValue(YSTRING("earlymedia"));
 		}
 		if (m_inbandAvailable)
 		    SignallingUtils::appendFlag(m->params(),"OptionalBackwardCallIndicators","inband");
@@ -2440,7 +2440,7 @@ bool SS7ISUPCall::sendEvent(SignallingEvent* event)
 	    break;
 	case SignallingEvent::Generic:
 	    if (event->message()) {
-		const String& oper = event->message()->params()["operation"];
+		const String& oper = event->message()->params()[YSTRING("operation")];
 		if (oper != "transport")
 		    break;
 		if (!validMsgState(true,SS7MsgISUP::APM))
@@ -2474,7 +2474,7 @@ bool SS7ISUPCall::sendEvent(SignallingEvent* event)
 	case SignallingEvent::Info:
 	    if (validMsgState(true,SS7MsgISUP::SAM)) {
 		mylock.drop();
-		transmitSAM(event->message()->params().getValue("tone"));
+		transmitSAM(event->message()->params().getValue(YSTRING("tone")));
 		result = true;
 		break;
 	    }
@@ -2498,9 +2498,9 @@ bool SS7ISUPCall::sendEvent(SignallingEvent* event)
 // Get reserved circuit or this object
 void* SS7ISUPCall::getObject(const String& name) const
 {
-    if (name == "SignallingCircuit")
+    if (name == YSTRING("SignallingCircuit"))
 	return m_circuit;
-    if (name == "SS7ISUPCall")
+    if (name == YSTRING("SS7ISUPCall"))
 	return (void*)this;
     return SignallingCall::getObject(name);
 }
@@ -2601,23 +2601,23 @@ bool SS7ISUPCall::copyParamIAM(SS7MsgISUP* msg, bool outgoing, SignallingMessage
 	param(dest,src,"CallingPartyNumber.restrict","callerpres",isup()->m_numPresentation);
 	param(dest,src,"CallingPartyNumber.screened","callerscreening",isup()->m_numScreening);
 	param(dest,src,"CallingPartyNumber.complete","complete","true");
-	m_format = src.getValue("format",isup()->format());
+	m_format = src.getValue(YSTRING("format"),isup()->format());
 	dest.addParam("UserServiceInformation",m_format);
 	return true;
     }
     // Incoming call
-    m_format = dest.getValue("UserServiceInformation",isup()->format());
+    m_format = dest.getValue(YSTRING("UserServiceInformation"),isup()->format());
     dest.setParam("format",m_format);
-    dest.setParam("caller",dest.getValue("CallingPartyNumber"));
+    dest.setParam("caller",dest.getValue(YSTRING("CallingPartyNumber")));
     //dest.setParam("callername",dest.getValue(""));
-    dest.setParam("callernumtype",dest.getValue("CallingPartyNumber.nature"));
-    dest.setParam("callernumplan",dest.getValue("CallingPartyNumber.plan"));
-    dest.setParam("callerpres",dest.getValue("CallingPartyNumber.restrict"));
-    dest.setParam("callerscreening",dest.getValue("CallingPartyNumber.screened"));
-    dest.setParam("called",dest.getValue("CalledPartyNumber"));
-    dest.setParam("callednumtype",dest.getValue("CalledPartyNumber.nature"));
-    dest.setParam("callednumplan",dest.getValue("CalledPartyNumber.plan"));
-    dest.setParam("inn",dest.getValue("CalledPartyNumber.inn"));
+    dest.setParam("callernumtype",dest.getValue(YSTRING("CallingPartyNumber.nature")));
+    dest.setParam("callernumplan",dest.getValue(YSTRING("CallingPartyNumber.plan")));
+    dest.setParam("callerpres",dest.getValue(YSTRING("CallingPartyNumber.restrict")));
+    dest.setParam("callerscreening",dest.getValue(YSTRING("CallingPartyNumber.screened")));
+    dest.setParam("called",dest.getValue(YSTRING("CalledPartyNumber")));
+    dest.setParam("callednumtype",dest.getValue(YSTRING("CalledPartyNumber.nature")));
+    dest.setParam("callednumplan",dest.getValue(YSTRING("CalledPartyNumber.plan")));
+    dest.setParam("inn",dest.getValue(YSTRING("CalledPartyNumber.inn")));
     if (m_label.sls() != 0xff)
 	dest.setParam("sls",String((unsigned int)m_label.sls()));
     return true;
@@ -2670,9 +2670,9 @@ void SS7ISUPCall::setReason(const char* reason, SignallingMessage* msg,
 	m_location = location;
     }
     else if (msg) {
-	m_reason = msg->params().getValue("CauseIndicators",msg->params().getValue("reason"));
-	m_diagnostic = msg->params().getValue("CauseIndicators.diagnostic",diagnostic);
-	m_location = msg->params().getValue("CauseIndicators.location",location);
+	m_reason = msg->params().getValue(YSTRING("CauseIndicators"),msg->params().getValue(YSTRING("reason")));
+	m_diagnostic = msg->params().getValue(YSTRING("CauseIndicators.diagnostic"),diagnostic);
+	m_location = msg->params().getValue(YSTRING("CauseIndicators.location"),location);
     }
 }
 
@@ -2865,7 +2865,7 @@ bool SS7ISUPCall::needsTesting(const SS7MsgISUP* msg)
 {
     if ((m_state >= Testing) || !msg)
 	return false;
-    const String* naci = msg->params().getParam("NatureOfConnectionIndicators");
+    const String* naci = msg->params().getParam(YSTRING("NatureOfConnectionIndicators"));
     if (!naci)
 	return false;
     ObjList* list = naci->split(',',false);
@@ -2887,12 +2887,12 @@ SignallingEvent* SS7ISUPCall::processSegmented(SS7MsgISUP* sgm, bool timeout)
 	    #define COPY_PARAM(param) \
 		m_sgmMsg->params().copyParam(sgm->params(),param); \
 		m_sgmMsg->params().copyParam(sgm->params(),param,'.');
-	    COPY_PARAM("AccessTranport")
-	    COPY_PARAM("UserToUserInformation")
-	    COPY_PARAM("MessageCompatInformation")
-	    COPY_PARAM("GenericDigits")
-	    COPY_PARAM("GenericNotification")
-	    COPY_PARAM("GenericNumber")
+	    COPY_PARAM(YSTRING("AccessTranport"))
+	    COPY_PARAM(YSTRING("UserToUserInformation"))
+	    COPY_PARAM(YSTRING("MessageCompatInformation"))
+	    COPY_PARAM(YSTRING("GenericDigits"))
+	    COPY_PARAM(YSTRING("GenericNotification"))
+	    COPY_PARAM(YSTRING("GenericNumber"))
 	    #undef COPY_PARAM
 	}
 	else
@@ -2907,8 +2907,8 @@ SignallingEvent* SS7ISUPCall::processSegmented(SS7MsgISUP* sgm, bool timeout)
     switch (m_sgmMsg->type()) {
 	case SS7MsgISUP::COT:
 	    {
-		const String* cont = m_sgmMsg->params().getParam("ContinuityIndicators");
-		bool ok = cont && (*cont == "success");
+		const String* cont = m_sgmMsg->params().getParam(YSTRING("ContinuityIndicators"));
+		bool ok = cont && (*cont == YSTRING("success"));
 		if (ok) {
 		    Debug(isup(),DebugNote,"Call(%u). Continuity check succeeded [%p]",
 			id(),this);
@@ -3141,7 +3141,7 @@ SS7ISUP::SS7ISUP(const NamedList& params, unsigned char sio)
 	    &params,this,tmp.c_str());
     }
 #endif
-    const char* stype = params.getValue("pointcodetype");
+    const char* stype = params.getValue(YSTRING("pointcodetype"));
     m_type = SS7PointCode::lookup(stype);
     if (m_type == SS7PointCode::Other) {
 	Debug(this,DebugWarn,"Invalid point code type '%s'",c_safe(stype));
@@ -3150,7 +3150,7 @@ SS7ISUP::SS7ISUP(const NamedList& params, unsigned char sio)
     if (m_type == SS7PointCode::ITU)
 	m_defaultSls = SlsCircuit;
 
-    m_format = params.getValue("format");
+    m_format = params.getValue(YSTRING("format"));
     if (-1 == lookup(m_format,SignallingUtils::dict(1,0),-1))
 	switch (m_type) {
 	    case SS7PointCode::ANSI:
@@ -3163,29 +3163,29 @@ SS7ISUP::SS7ISUP(const NamedList& params, unsigned char sio)
 		m_format = "alaw";
 	}
 
-    const char* rpc = params.getValue("remotepointcode");
+    const char* rpc = params.getValue(YSTRING("remotepointcode"));
     m_remotePoint = new SS7PointCode(0,0,0);
     if (!(m_remotePoint->assign(rpc,m_type) && m_remotePoint->pack(m_type))) {
 	Debug(this,DebugMild,"Invalid remotepointcode='%s'",rpc);
 	TelEngine::destruct(m_remotePoint);
     }
 
-    m_lockGroup = params.getBoolValue("lockgroup",m_lockGroup);
-    m_earlyAcm = params.getBoolValue("earlyacm",m_earlyAcm);
-    m_inn = params.getBoolValue("inn",m_inn);
-    m_numPlan = params.getValue("numplan");
+    m_lockGroup = params.getBoolValue(YSTRING("lockgroup"),m_lockGroup);
+    m_earlyAcm = params.getBoolValue(YSTRING("earlyacm"),m_earlyAcm);
+    m_inn = params.getBoolValue(YSTRING("inn"),m_inn);
+    m_numPlan = params.getValue(YSTRING("numplan"));
     if (-1 == lookup(m_numPlan,s_dict_numPlan,-1))
 	m_numPlan = "unknown";
-    m_numType = params.getValue("numtype");
+    m_numType = params.getValue(YSTRING("numtype"));
     if (-1 == lookup(m_numType,s_dict_nai,-1))
 	m_numType = "unknown";
-    m_numPresentation = params.getValue("presentation");
+    m_numPresentation = params.getValue(YSTRING("presentation"));
     if (-1 == lookup(m_numPresentation,s_dict_presentation,-1))
 	m_numPresentation = "allowed";
-    m_numScreening = params.getValue("screening");
+    m_numScreening = params.getValue(YSTRING("screening"));
     if (-1 == lookup(m_numScreening,s_dict_screening,-1))
 	m_numScreening = "user-provided";
-    m_callerCat = params.getValue("callercategory");
+    m_callerCat = params.getValue(YSTRING("callercategory"));
     if (-1 == lookup(m_callerCat,s_dict_callerCat,-1))
 	m_callerCat = "ordinary";
 
@@ -3202,15 +3202,15 @@ SS7ISUP::SS7ISUP(const NamedList& params, unsigned char sio)
     // Timers
     m_t9Interval = SignallingTimer::getInterval(params,"t9",ISUP_T9_MINVAL,0,ISUP_T9_MAXVAL,true);
 
-    m_continuity = params.getValue("continuity");
-    m_confirmCCR = params.getBoolValue("confirm_ccr",true);
-    m_dropOnUnknown = params.getBoolValue("drop_unknown",true);
-    m_ignoreGRSSingle = params.getBoolValue("ignore-grs-single");
-    m_ignoreCGBSingle = params.getBoolValue("ignore-cgb-single");
-    m_ignoreCGUSingle = params.getBoolValue("ignore-cgu-single");
-    m_duplicateCGB = params.getBoolValue("duplicate-cgb",
+    m_continuity = params.getValue(YSTRING("continuity"));
+    m_confirmCCR = params.getBoolValue(YSTRING("confirm_ccr"),true);
+    m_dropOnUnknown = params.getBoolValue(YSTRING("drop_unknown"),true);
+    m_ignoreGRSSingle = params.getBoolValue(YSTRING("ignore-grs-single"));
+    m_ignoreCGBSingle = params.getBoolValue(YSTRING("ignore-cgb-single"));
+    m_ignoreCGUSingle = params.getBoolValue(YSTRING("ignore-cgu-single"));
+    m_duplicateCGB = params.getBoolValue(YSTRING("duplicate-cgb"),
 	(SS7PointCode::ANSI == m_type || SS7PointCode::ANSI8 == m_type));
-    int testMsg = params.getIntValue("parttestmsg",s_names,SS7MsgISUP::UPT);
+    int testMsg = params.getIntValue(YSTRING("parttestmsg"),s_names,SS7MsgISUP::UPT);
     switch (testMsg) {
 	case SS7MsgISUP::CVT:
 	    if (SS7PointCode::ANSI != m_type && SS7PointCode::ANSI8 != m_type)
@@ -3221,14 +3221,14 @@ SS7ISUP::SS7ISUP(const NamedList& params, unsigned char sio)
 	case SS7MsgISUP::UPT:
 	    m_uptMessage = (SS7MsgISUP::Type)testMsg;
     }
-    m_ignoreUnkDigits = params.getBoolValue("ignore-unknown-digits",true);
-    m_defaultSls = params.getIntValue("sls",s_dict_callSls,m_defaultSls);
-    m_maxCalledDigits = params.getIntValue("maxcalleddigits",m_maxCalledDigits);
+    m_ignoreUnkDigits = params.getBoolValue(YSTRING("ignore-unknown-digits"),true);
+    m_defaultSls = params.getIntValue(YSTRING("sls"),s_dict_callSls,m_defaultSls);
+    m_maxCalledDigits = params.getIntValue(YSTRING("maxcalleddigits"),m_maxCalledDigits);
     if (m_maxCalledDigits < 1)
 	m_maxCalledDigits = 16;
 
-    setDebug(params.getBoolValue("print-messages",false),
-	params.getBoolValue("extended-debug",false));
+    setDebug(params.getBoolValue(YSTRING("print-messages"),false),
+	params.getBoolValue(YSTRING("extended-debug"),false));
 
     if (debugAt(DebugInfo)) {
 	String s;
@@ -3243,7 +3243,7 @@ SS7ISUP::SS7ISUP(const NamedList& params, unsigned char sio)
 	else
 	    s << "missing";
 	s << " SIF/SSF=" << (unsigned int)sif() << "/" << (unsigned int)ssf();
-	s << " lockcircuits=" << params.getValue("lockcircuits");
+	s << " lockcircuits=" << params.getValue(YSTRING("lockcircuits"));
 	s << " userpartavail=" << String::boolText(m_userPartAvail);
 	s << " lockgroup=" << String::boolText(m_lockGroup);
 	s << " mediareq=" << lookup(m_mediaRequired,s_mediaRequired);
@@ -3276,21 +3276,21 @@ bool SS7ISUP::initialize(const NamedList* config)
     Debug(this,DebugInfo,"SS7ISUP::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
     if (config) {
-	debugLevel(config->getIntValue("debuglevel_isup",
-	    config->getIntValue("debuglevel",-1)));
-	setDebug(config->getBoolValue("print-messages",false),
-	    config->getBoolValue("extended-debug",false));
-	m_lockGroup = config->getBoolValue("lockgroup",m_lockGroup);
-	m_earlyAcm = config->getBoolValue("earlyacm",m_earlyAcm);
-	m_continuity = config->getValue("continuity",m_continuity);
-	m_confirmCCR = config->getBoolValue("confirm_ccr",true);
-	m_dropOnUnknown = config->getBoolValue("drop_unknown",true);
-	m_ignoreGRSSingle = config->getBoolValue("ignore-grs-single");
-	m_ignoreCGBSingle = config->getBoolValue("ignore-cgb-single");
-	m_ignoreCGUSingle = config->getBoolValue("ignore-cgu-single");
-	m_duplicateCGB = config->getBoolValue("duplicate-cgb",
+	debugLevel(config->getIntValue(YSTRING("debuglevel_isup"),
+	    config->getIntValue(YSTRING("debuglevel"),-1)));
+	setDebug(config->getBoolValue(YSTRING("print-messages"),false),
+	    config->getBoolValue(YSTRING("extended-debug"),false));
+	m_lockGroup = config->getBoolValue(YSTRING("lockgroup"),m_lockGroup);
+	m_earlyAcm = config->getBoolValue(YSTRING("earlyacm"),m_earlyAcm);
+	m_continuity = config->getValue(YSTRING("continuity"),m_continuity);
+	m_confirmCCR = config->getBoolValue(YSTRING("confirm_ccr"),true);
+	m_dropOnUnknown = config->getBoolValue(YSTRING("drop_unknown"),true);
+	m_ignoreGRSSingle = config->getBoolValue(YSTRING("ignore-grs-single"));
+	m_ignoreCGBSingle = config->getBoolValue(YSTRING("ignore-cgb-single"));
+	m_ignoreCGUSingle = config->getBoolValue(YSTRING("ignore-cgu-single"));
+	m_duplicateCGB = config->getBoolValue(YSTRING("duplicate-cgb"),
 	    (SS7PointCode::ANSI == m_type || SS7PointCode::ANSI8 == m_type));
-	int testMsg = config->getIntValue("parttestmsg",s_names,SS7MsgISUP::UPT);
+	int testMsg = config->getIntValue(YSTRING("parttestmsg"),s_names,SS7MsgISUP::UPT);
 	switch (testMsg) {
 	    case SS7MsgISUP::CVT:
 		if (SS7PointCode::ANSI != m_type && SS7PointCode::ANSI8 != m_type)
@@ -3301,9 +3301,9 @@ bool SS7ISUP::initialize(const NamedList* config)
 	    case SS7MsgISUP::UPT:
 		m_uptMessage = (SS7MsgISUP::Type)testMsg;
 	}
-        m_ignoreUnkDigits = config->getBoolValue("ignore-unknown-digits",true);
-	m_defaultSls = config->getIntValue("sls",s_dict_callSls,m_defaultSls);
-	m_mediaRequired = (MediaRequired)config->getIntValue("needmedia",
+        m_ignoreUnkDigits = config->getBoolValue(YSTRING("ignore-unknown-digits"),true);
+	m_defaultSls = config->getIntValue(YSTRING("sls"),s_dict_callSls,m_defaultSls);
+	m_mediaRequired = (MediaRequired)config->getIntValue(YSTRING("needmedia"),
 	    s_mediaRequired,m_mediaRequired);
         // Timers
 	m_t9Interval = SignallingTimer::getInterval(*config,"t9",ISUP_T9_MINVAL,0,ISUP_T9_MAXVAL,true);
@@ -3373,9 +3373,9 @@ unsigned int SS7ISUP::setPointCode(const NamedList& params)
 	if (!ns)
 	    continue;
 	bool defPc = false;
-	if (ns->name() == "defaultpointcode")
+	if (ns->name() == YSTRING("defaultpointcode"))
 	    defPc = true;
-	else if (ns->name() != "pointcode")
+	else if (ns->name() != YSTRING("pointcode"))
 	    continue;
 	SS7PointCode* pc = new SS7PointCode(0,0,0);
 	if (pc->assign(*ns,m_type) && setPointCode(pc,defPc && !hadDef)) {
@@ -3436,7 +3436,7 @@ SignallingCall* SS7ISUP::call(SignallingMessage* msg, String& reason)
     }
     SS7PointCode dest;
     SignallingCircuit* cic = 0;
-    const char* range = msg->params().getValue("circuits");
+    const char* range = msg->params().getValue(YSTRING("circuits"));
     reason.clear();
     Lock mylock(this);
     // Check
@@ -3446,7 +3446,7 @@ SignallingCall* SS7ISUP::call(SignallingMessage* msg, String& reason)
 	    reason = "noconn";
 	    break;
 	}
-	String pc = msg->params().getValue("calledpointcode");
+	String pc = msg->params().getValue(YSTRING("calledpointcode"));
 	if (!(dest.assign(pc,m_type) && dest.pack(m_type))) {
 	    if (!m_remotePoint) {
 		Debug(this,DebugNote,
@@ -3474,13 +3474,13 @@ SignallingCall* SS7ISUP::call(SignallingMessage* msg, String& reason)
     }
     SS7ISUPCall* call = 0;
     if (reason.null()) {
-	String* cicParams = msg->params().getParam("circuit_parameters");
+	String* cicParams = msg->params().getParam(YSTRING("circuit_parameters"));
 	if (cicParams) {
 	    NamedList* p = YOBJECT(NamedList,cicParams);
 	    if (p)
 		cic->setParams(*p);
 	}
-	int sls = msg->params().getIntValue("sls",s_dict_callSls,m_defaultSls);
+	int sls = msg->params().getIntValue(YSTRING("sls"),s_dict_callSls,m_defaultSls);
 	switch (sls) {
 	    case SlsCircuit:
 		if (cic) {
@@ -3674,8 +3674,8 @@ void SS7ISUP::timerTick(const Time& when)
 		continue;
 	    }
 	}
-	bool alert = msg->params().getBoolValue("isup_alert_maint");
-	const char* reason = msg->params().getValue("isup_pending_reason","");
+	bool alert = msg->params().getBoolValue(YSTRING("isup_alert_maint"));
+	const char* reason = msg->params().getValue(YSTRING("isup_pending_reason"),"");
 	Debug(this,!alert ? DebugAll : DebugMild,
 	    "Pending operation '%s' cic=%u reason='%s' timed out",
 	    msg->name(),msg->cic(),reason);
@@ -3742,15 +3742,15 @@ void SS7ISUP::timerTick(const Time& when)
 // Process a component control request
 bool SS7ISUP::control(NamedList& params)
 {
-    String* ret = params.getParam("completion");
-    const String* oper = params.getParam("operation");
-    const char* cmp = params.getValue("component");
+    String* ret = params.getParam(YSTRING("completion"));
+    const String* oper = params.getParam(YSTRING("operation"));
+    const char* cmp = params.getValue(YSTRING("component"));
     int cmd = oper ? oper->toInteger(s_dict_control,-1) : -1;
 
     if (ret) {
 	if (oper && (cmd < 0))
 	    return false;
-	String part = params.getValue("partword");
+	String part = params.getValue(YSTRING("partword"));
 	if (cmp) {
 	    if (toString() != cmp)
 		return false;
@@ -3773,7 +3773,7 @@ bool SS7ISUP::control(NamedList& params)
 	case SS7MsgISUP::UPT:
 	case SS7MsgISUP::CVT:
 	    {
-		unsigned int code = params.getIntValue("circuit",code1);
+		unsigned int code = params.getIntValue(YSTRING("circuit"),code1);
 		SS7MsgISUP* msg = new SS7MsgISUP((SS7MsgISUP::Type)cmd,code);
 		SS7Label label(m_type,*m_remotePoint,*m_defPoint,m_sls);
 		mylock.drop();
@@ -3782,8 +3782,8 @@ bool SS7ISUP::control(NamedList& params)
 	    return true;
 	case SS7MsgISUP::CQM:
 	    {
-		unsigned int code = params.getIntValue("circuit",code1);
-		unsigned int range = params.getIntValue("range",1);
+		unsigned int code = params.getIntValue(YSTRING("circuit"),code1);
+		unsigned int range = params.getIntValue(YSTRING("range"),1);
 		SS7MsgISUP* msg = new SS7MsgISUP(SS7MsgISUP::CQM,code);
 		msg->params().addParam("RangeAndStatus",String(range));
 		SS7Label label(m_type,*m_remotePoint,*m_defPoint,m_sls);
@@ -3793,7 +3793,7 @@ bool SS7ISUP::control(NamedList& params)
 	    return true;
 	case SS7MsgISUP::CCR:
 	    {
-		unsigned int code = params.getIntValue("circuit",code1);
+		unsigned int code = params.getIntValue(YSTRING("circuit"),code1);
 		// TODO: create a test call, not just send CCR
 		SS7MsgISUP* msg = new SS7MsgISUP(SS7MsgISUP::CCR,code);
 		SS7Label label(m_type,*m_remotePoint,*m_defPoint,m_sls);
@@ -3816,7 +3816,7 @@ bool SS7ISUP::control(NamedList& params)
 	    return handleCicBlockCommand(params,cmd == SS7MsgISUP::BLK);
 	case SS7MsgISUP::RLC:
 	    {
-		int code = params.getIntValue("circuit");
+		int code = params.getIntValue(YSTRING("circuit"));
 		SignallingMessageTimer* pending = 0;
 		if (code > 0)
 		    pending = findPendingMessage(SS7MsgISUP::RSC,code,true);
@@ -3942,7 +3942,7 @@ SS7MSU* SS7ISUP::buildMSU(SS7MsgISUP::Type type, unsigned char sio,
 #endif
     ObjList exclude;
     plist = msgParams->params;
-    String prefix = params->getValue("message-prefix");
+    String prefix = params->getValue(YSTRING("message-prefix"));
     // first populate with mandatory fixed parameters
     while ((ptype = *plist++) != SS7MsgISUP::EndOfParameters) {
 	const IsupParam* param = getParamDesc(ptype);
@@ -4066,7 +4066,7 @@ bool SS7ISUP::decodeMessage(NamedList& msg,
     }
 
     // Get parameter prefix
-    String prefix = msg.getValue("message-prefix");
+    String prefix = msg.getValue(YSTRING("message-prefix"));
 
     // Add protocol and message type
     switch (pcType) {
@@ -4213,13 +4213,13 @@ bool SS7ISUP::decodeMessage(NamedList& msg,
 	ObjList* l = ns->split(',',false);
 	for (ObjList* ol = l->skipNull(); ol; ol = ol->skipNext()) {
 	    String* s = static_cast<String*>(ol->get());
-	    if (*s == "release") {
+	    if (*s == YSTRING("release")) {
 		release.append(ns->name().substr(pCompat.length()),",");
 		break;
 	    }
-	    if (*s == "cnf")
+	    if (*s == YSTRING("cnf"))
 		cnf.append(ns->name().substr(pCompat.length()),",");
-	    if (*s == "nopass-release")
+	    if (*s == YSTRING("nopass-release"))
 		npRelease.append(ns->name().substr(pCompat.length()),",");
 	}
 	TelEngine::destruct(l);
@@ -4259,7 +4259,7 @@ bool SS7ISUP::processParamCompat(const NamedList& list, unsigned int cic, bool*
 {
     if (!cic)
 	return true;
-    const String& prefix = list["message-prefix"];
+    const String& prefix = list[YSTRING("message-prefix")];
     // Release call params
     String relCall = list[prefix + "parameters-unhandled-release"];
     relCall.append(list[prefix + "parameters-nopass-release"],",");
@@ -4466,10 +4466,10 @@ SignallingEvent* SS7ISUP::processCircuitEvent(SignallingCircuitEvent*& event,
 	    }
 	    break;
 	case SignallingCircuitEvent::Dtmf:
-	    if (event->getValue("tone")) {
+	    if (event->getValue(YSTRING("tone"))) {
 		SignallingMessage* msg = new SignallingMessage(event->c_str());
-		msg->params().addParam("tone",event->getValue("tone"));
-		msg->params().addParam("inband",event->getValue("inband",String::boolText(true)));
+		msg->params().addParam("tone",event->getValue(YSTRING("tone")));
+		msg->params().addParam("inband",event->getValue(YSTRING("inband"),String::boolText(true)));
 		ev = new SignallingEvent(SignallingEvent::Info,msg,call);
 		TelEngine::destruct(msg);
 	    }
@@ -4598,7 +4598,7 @@ void SS7ISUP::processCallMsg(SS7MsgISUP* msg, const SS7Label& label, int sls)
 	// Q.764 2.8.2 - accept test calls even if the remote side is blocked
 	// Q.764 2.8.2.3 (xiv) - unblock remote side of the circuit for non-test calls
 	if ((msg->type() == SS7MsgISUP::CCR) ||
-	    (String(msg->params().getValue("CallingPartyCategory")) == "test")) {
+	    (msg->params()[YSTRING("CallingPartyCategory")] == YSTRING("test"))) {
 	    Debug(this,DebugInfo,"Received test call on circuit %u",msg->cic());
 	    flags = 0;
 	}
@@ -4641,12 +4641,12 @@ void SS7ISUP::processCallMsg(SS7MsgISUP* msg, const SS7Label& label, int sls)
 unsigned int getRangeAndStatus(NamedList& nl, unsigned int minRange, unsigned int maxRange,
     unsigned int maxMap = 0, String** map = 0, unsigned int nCicsMax = 0)
 {
-    unsigned int range = nl.getIntValue("RangeAndStatus");
+    unsigned int range = nl.getIntValue(YSTRING("RangeAndStatus"));
     if (range < minRange || range > maxRange)
 	return 0;
     if (!maxMap)
 	return range;
-    NamedString* ns = nl.getParam("RangeAndStatus.map");
+    NamedString* ns = nl.getParam(YSTRING("RangeAndStatus.map"));
     if (!ns || ns->length() > maxMap || ns->length() < range)
 	return 0;
     if (map) {
@@ -4671,9 +4671,9 @@ static bool getGrpTypeInd(SS7ISUP* isup, SS7MsgISUP* msg, bool& hwFail)
 {
     if (!msg)
 	return false;
-    const String& s = msg->params()["GroupSupervisionTypeIndicator"];
-    hwFail = (s == "hw-failure");
-    if (hwFail || (s == "maintenance"))
+    const String& s = msg->params()[YSTRING("GroupSupervisionTypeIndicator")];
+    hwFail = (s == YSTRING("hw-failure"));
+    if (hwFail || (s == YSTRING("maintenance")))
 	return true;
     Debug(isup,DebugNote,"%s with unknown GroupSupervisionTypeIndicator=%s [%p]",
 	msg->name(),s.c_str(),isup);
@@ -4703,8 +4703,8 @@ void SS7ISUP::processControllerMsg(SS7MsgISUP* msg, const SS7Label& label, int s
 	    // TODO: check if this message was received in response to RSC, UBL, UBK, CGB, CGU
 	    Debug(this,DebugNote,"%s with cic=%u cause='%s' diagnostic='%s'",
 		msg->name(),msg->cic(),
-		msg->params().getValue("CauseIndicators"),
-		msg->params().getValue("CauseIndicators.diagnostic"));
+		msg->params().getValue(YSTRING("CauseIndicators")),
+		msg->params().getValue(YSTRING("CauseIndicators.diagnostic")));
 	    stopSGM = true;
 	    break;
 	case SS7MsgISUP::RLC: // Release Complete
@@ -4736,7 +4736,7 @@ void SS7ISUP::processControllerMsg(SS7MsgISUP* msg, const SS7Label& label, int s
 		unsigned int n = getRangeAndStatus(msg->params(),1,31);
 		if (!n) {
 		    Debug(this,DebugNote,"%s with invalid range %s",msg->name(),
-			msg->params().getValue("RangeAndStatus"));
+			msg->params().getValue(YSTRING("RangeAndStatus")));
 		    break;
 		}
 		else if (n == 1 && m_ignoreGRSSingle) {
@@ -4777,7 +4777,7 @@ void SS7ISUP::processControllerMsg(SS7MsgISUP* msg, const SS7Label& label, int s
 		SignallingMessageTimer* t = findPendingMessage(type,msg->cic(),true);
 		if (t) {
 		    SS7MsgISUP* m = static_cast<SS7MsgISUP*>(t->message());
-		    bool hw = m && m->params().getBoolValue("isup_pending_block_hwfail");
+		    bool hw = m && m->params().getBoolValue(YSTRING("isup_pending_block_hwfail"));
 		    DDebug(this,m ? DebugAll : DebugNote,"%s confirmed for pending cic=%u",
 			  block ? "BLK" : "UBL",msg->cic());
 		    TelEngine::destruct(t);
@@ -4800,8 +4800,8 @@ void SS7ISUP::processControllerMsg(SS7MsgISUP* msg, const SS7Label& label, int s
 		unsigned int nCics = getRangeAndStatus(msg->params(),1,256,256,&srcMap,32);
 		if (!nCics) {
 		    Debug(this,DebugNote,"%s with invalid range %s or map=%s",msg->name(),
-			msg->params().getValue("RangeAndStatus"),
-			msg->params().getValue("RangeAndStatus.map"));
+			msg->params().getValue(YSTRING("RangeAndStatus")),
+			msg->params().getValue(YSTRING("RangeAndStatus.map")));
 		    break;
 		}
 		bool block = (msg->type() == SS7MsgISUP::CGA);
@@ -4813,11 +4813,11 @@ void SS7ISUP::processControllerMsg(SS7MsgISUP* msg, const SS7Label& label, int s
 		String map;
 		while (m) {
 		    // Check type indicator
-		    bool hw = (m->params()["GroupSupervisionTypeIndicator"] == "hw-failure");
+		    bool hw = (m->params()[YSTRING("GroupSupervisionTypeIndicator")] == YSTRING("hw-failure"));
 		    if (hw != hwFail)
 			break;
 		    // Check map
-		    map = m->params()["RangeAndStatus.map"];
+		    map = m->params()[YSTRING("RangeAndStatus.map")];
 		    if (!map)
 			break;
 		    if (map.length() != nCics) {
@@ -4838,8 +4838,8 @@ void SS7ISUP::processControllerMsg(SS7MsgISUP* msg, const SS7Label& label, int s
 		unlock();
 		if (!map) {
 		    Debug(this,DebugNote,"%s with unnacceptable range %s or map=%s",msg->name(),
-			msg->params().getValue("RangeAndStatus"),
-			msg->params().getValue("RangeAndStatus.map"));
+			msg->params().getValue(YSTRING("RangeAndStatus")),
+			msg->params().getValue(YSTRING("RangeAndStatus.map")));
 		    break;
 		}
 		for (unsigned int i = 0; i < map.length(); i++)
@@ -4861,8 +4861,8 @@ void SS7ISUP::processControllerMsg(SS7MsgISUP* msg, const SS7Label& label, int s
 		unsigned int nCics = getRangeAndStatus(msg->params(),1,256,256,&srcMap,32);
 		if (!nCics) {
 		    Debug(this,DebugNote,"%s with invalid range %s or map=%s",msg->name(),
-			msg->params().getValue("RangeAndStatus"),
-			msg->params().getValue("RangeAndStatus.map"));
+			msg->params().getValue(YSTRING("RangeAndStatus")),
+			msg->params().getValue(YSTRING("RangeAndStatus.map")));
 		    break;
 		}
 		else if (nCics == 1 && ((block && m_ignoreCGBSingle) || (!block && m_ignoreCGUSingle))) {
@@ -5336,8 +5336,8 @@ bool SS7ISUP::handleCicBlockCommand(const NamedList& p, bool block)
 	return false;
     SS7MsgISUP* msg = 0;
     SS7MsgISUP::Type remove = SS7MsgISUP::Unknown;
-    bool force = p.getBoolValue("force");
-    String* param = p.getParam("circuit");
+    bool force = p.getBoolValue(YSTRING("force"));
+    String* param = p.getParam(YSTRING("circuit"));
     Lock mylock(this);
     if (param) {
 	SignallingCircuit* cic = circuits()->find(param->toInteger());
@@ -5349,10 +5349,10 @@ bool SS7ISUP::handleCicBlockCommand(const NamedList& p, bool block)
     }
     else {
 	// NOTE: we assume the circuits belongs to the same span
-	param = p.getParam("circuits");
+	param = p.getParam(YSTRING("circuits"));
 	if (TelEngine::null(param)) {
 	    Debug(this,DebugNote,"Circuit '%s' missing circuit(s)",
-		p.getValue("operation"));
+		p.getValue(YSTRING("operation")));
 	    return false;
 	}
 	// Parse the range
@@ -5362,7 +5362,7 @@ bool SS7ISUP::handleCicBlockCommand(const NamedList& p, bool block)
 	    SignallingCircuitRange* range = circuits()->findRange(*param);
 	    if (!(range && (count = range->count()))) {
 		Debug(this,DebugNote,"Circuit group '%s': invalid circuits=%s",
-		    p.getValue("operation"),param->c_str());
+		    p.getValue(YSTRING("operation")),param->c_str());
 		return false;
 	    }
 	    cics = new unsigned int[count];
@@ -5371,19 +5371,19 @@ bool SS7ISUP::handleCicBlockCommand(const NamedList& p, bool block)
 	}
 	if (count > 32) {
 	    Debug(this,DebugNote,"Circuit group '%s': too many circuits %u (max=32)",
-		p.getValue("operation"),count);
+		p.getValue(YSTRING("operation")),count);
 	    delete[] cics;
 	    return false;
 	}
 	// Check if all circuits can be (un)blocked
 	ObjList list;
-	bool maint = !p.getBoolValue("hwfail");
+	bool maint = !p.getBoolValue(YSTRING("hwfail"));
 	for (unsigned int i = 0; i < count; i++) {
 	    SignallingCircuit* c = circuits()->find(cics[i]);
 	    const char* reason = checkBlockCic(c,block,maint,force);
 	    if (reason) {
 		Debug(this,DebugNote,"Circuit group '%s' range=%s failed for cic=%u: %s",
-		    p.getValue("operation"),param->c_str(),cics[i],reason);
+		    p.getValue(YSTRING("operation")),param->c_str(),cics[i],reason);
 		delete[] cics;
 		return false;
 	    }
@@ -5413,7 +5413,7 @@ bool SS7ISUP::handleCicBlockCommand(const NamedList& p, bool block)
 	delete[] cics;
 	if (nCics != count) {
 	    Debug(this,DebugNote,"Circuit group '%s': invalid circuit map=%s",
-		p.getValue("operation"),param->c_str());
+		p.getValue(YSTRING("operation")),param->c_str());
 	    return false;
 	}
 	// Ok: block circuits and send the request
diff --git a/libs/ysig/layer2.cpp b/libs/ysig/layer2.cpp
index 6340193f..a60c19d0 100644
--- a/libs/ysig/layer2.cpp
+++ b/libs/ysig/layer2.cpp
@@ -205,14 +205,14 @@ bool SS7Layer2::control(Operation oper, NamedList* params)
 
 bool SS7Layer2::control(NamedList& params)
 {
-    String* ret = params.getParam("completion");
-    const String* oper = params.getParam("operation");
-    const char* cmp = params.getValue("component");
+    String* ret = params.getParam(YSTRING("completion"));
+    const String* oper = params.getParam(YSTRING("operation"));
+    const char* cmp = params.getValue(YSTRING("component"));
     int cmd = oper ? oper->toInteger(s_dict_control,-1) : -1;
     if (ret) {
 	if (oper && (cmd < 0))
 	    return false;
-	String part = params.getValue("partword");
+	String part = params.getValue(YSTRING("partword"));
 	if (cmp) {
 	    if (toString() != cmp)
 		return false;
@@ -235,7 +235,7 @@ bool SS7Layer2::getEmergency(NamedList* params, bool emg) const
 	    emg = true;
     }
     if (params)
-	emg = params->getBoolValue("emergency",emg);
+	emg = params->getBoolValue(YSTRING("emergency"),emg);
     return emg;
 }
 
@@ -277,13 +277,13 @@ SS7MTP2::SS7MTP2(const NamedList& params, unsigned int status)
 	    &params,statusName(true),this,tmp.c_str());
     }
 #endif
-    m_fillLink = params.getBoolValue("filllink",m_fillLink);
-    m_maxErrors = params.getIntValue("maxerrors",64);
+    m_fillLink = params.getBoolValue(YSTRING("filllink"),m_fillLink);
+    m_maxErrors = params.getIntValue(YSTRING("maxerrors"),64);
     if (m_maxErrors < 8)
 	m_maxErrors = 8;
     else if (m_maxErrors > 256)
 	m_maxErrors = 256;
-    setDumper(params.getValue("layer2dump"));
+    setDumper(params.getValue(YSTRING("layer2dump")));
 }
 
 SS7MTP2::~SS7MTP2()
@@ -335,10 +335,10 @@ bool SS7MTP2::initialize(const NamedList* config)
     Debug(this,DebugInfo,"SS7MTP2::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
     if (config) {
-	debugLevel(config->getIntValue("debuglevel_mtp2",
-	    config->getIntValue("debuglevel",-1)));
-	m_autoEmergency = config->getBoolValue("autoemergency",true);
-	unsigned int maxErrors = config->getIntValue("maxerrors",m_maxErrors);
+	debugLevel(config->getIntValue(YSTRING("debuglevel_mtp2"),
+	    config->getIntValue(YSTRING("debuglevel"),-1)));
+	m_autoEmergency = config->getBoolValue(YSTRING("autoemergency"),true);
+	unsigned int maxErrors = config->getIntValue(YSTRING("maxerrors"),m_maxErrors);
 	if (maxErrors < 8)
 	    m_maxErrors = 8;
 	else if (maxErrors > 256)
@@ -346,12 +346,12 @@ bool SS7MTP2::initialize(const NamedList* config)
 	else
 	    m_maxErrors = maxErrors;
     }
-    m_autostart = !config || config->getBoolValue("autostart",true);
-    m_flushMsus = !config || config->getBoolValue("flushmsus",true);
+    m_autostart = !config || config->getBoolValue(YSTRING("autostart"),true);
+    m_flushMsus = !config || config->getBoolValue(YSTRING("flushmsus"),true);
     if (config && !iface()) {
-	NamedString* name = config->getParam("sig");
+	NamedString* name = config->getParam(YSTRING("sig"));
 	if (!name)
-	    name = config->getParam("basename");
+	    name = config->getParam(YSTRING("basename"));
 	if (name) {
 	    NamedPointer* ptr = YOBJECT(NamedPointer,name);
 	    NamedList* ifConfig = ptr ? YOBJECT(NamedList,ptr->userData()) : 0;
@@ -360,7 +360,7 @@ bool SS7MTP2::initialize(const NamedList* config)
 	    params.addParam("protocol","ss7");
 	    if (ifConfig) {
 		params.copyParams(*ifConfig);
-		int rx = params.getIntValue("rxunderrun");
+		int rx = params.getIntValue(YSTRING("rxunderrun"));
 		if ((rx > 0) && (rx < 25))
 		    params.setParam("rxunderrun","25");
 	    }
@@ -383,11 +383,11 @@ bool SS7MTP2::control(Operation oper, NamedList* params)
 {
     if (params) {
 	lock();
-	m_fillLink = params->getBoolValue("filllink",m_fillLink);
-	m_autoEmergency = params->getBoolValue("autoemergency",m_autoEmergency);
-	m_autostart = params->getBoolValue("autostart",m_autostart);
-	m_flushMsus = params->getBoolValue("flushmsus",m_flushMsus);
-	unsigned int maxErrors = params->getIntValue("maxerrors",m_maxErrors);
+	m_fillLink = params->getBoolValue(YSTRING("filllink"),m_fillLink);
+	m_autoEmergency = params->getBoolValue(YSTRING("autoemergency"),m_autoEmergency);
+	m_autostart = params->getBoolValue(YSTRING("autostart"),m_autostart);
+	m_flushMsus = params->getBoolValue(YSTRING("flushmsus"),m_flushMsus);
+	unsigned int maxErrors = params->getIntValue(YSTRING("maxerrors"),m_maxErrors);
 	if (maxErrors < 8)
 	    m_maxErrors = 8;
 	else if (maxErrors > 256)
@@ -395,20 +395,20 @@ bool SS7MTP2::control(Operation oper, NamedList* params)
 	else
 	    m_maxErrors = maxErrors;
 	// The following are for test purposes
-	if (params->getBoolValue("toggle-bib"))
+	if (params->getBoolValue(YSTRING("toggle-bib")))
 	    m_bib = !m_bib;
-	if (params->getBoolValue("toggle-fib"))
+	if (params->getBoolValue(YSTRING("toggle-fib")))
 	    m_fib = !m_fib;
-	int tmp = params->getIntValue("change-fsn");
+	int tmp = params->getIntValue(YSTRING("change-fsn"));
 	if (tmp)
 	    m_fsn = (m_fsn + tmp) & 0x7f;
 	unlock();
-	tmp = params->getIntValue("send-lssu",-1);
+	tmp = params->getIntValue(YSTRING("send-lssu"),-1);
 	if (tmp >= 0)
 	    transmitLSSU(tmp);
-	if (params->getBoolValue("send-fisu"))
+	if (params->getBoolValue(YSTRING("send-fisu")))
 	    transmitFISU();
-	if (params->getBoolValue("simulate-error"))
+	if (params->getBoolValue(YSTRING("simulate-error")))
 	    notify(SignallingInterface::HardwareError);
     }
     switch (oper) {
diff --git a/libs/ysig/layer3.cpp b/libs/ysig/layer3.cpp
index fc279707..1b79043c 100644
--- a/libs/ysig/layer3.cpp
+++ b/libs/ysig/layer3.cpp
@@ -71,11 +71,11 @@ SS7Layer3::SS7Layer3(SS7PointCode::Type type)
 bool SS7Layer3::initialize(const NamedList* config)
 {
     if (config)
-	setNI(SS7MSU::getNetIndicator(config->getValue("netindicator"),SS7MSU::National));
+	setNI(SS7MSU::getNetIndicator(config->getValue(YSTRING("netindicator")),SS7MSU::National));
     if (engine() && !user()) {
 	NamedList params("ss7router");
 	if (config)
-	    static_cast<String&>(params) = config->getValue("router",params);
+	    static_cast<String&>(params) = config->getValue(YSTRING("router"),params);
 	if (params.toBoolean(true))
 	    SS7Layer3::attach(YOBJECT(SS7Router,engine()->build("SS7Router",params,true)));
     }
@@ -95,7 +95,7 @@ void SS7Layer3::attach(SS7L3User* l3user)
 	const char* name = 0;
 	if (engine() && engine()->find(tmp)) {
 	    name = tmp->toString().safe();
-	    if (tmp->getObject("SS7Router"))
+	    if (tmp->getObject(YSTRING("SS7Router")))
 		(static_cast<SS7Router*>(tmp))->detach(this);
 	    else
 		tmp->attach(0);
@@ -106,7 +106,7 @@ void SS7Layer3::attach(SS7L3User* l3user)
 	return;
     Debug(this,DebugAll,"Attached L3 user (%p,'%s') [%p]",l3user,l3user->toString().safe(),this);
     insert(l3user);
-    if (l3user->getObject("SS7Router"))
+    if (l3user->getObject(YSTRING("SS7Router")))
 	(static_cast<SS7Router*>(l3user))->attach(this);
     else
 	l3user->attach(this);
@@ -182,11 +182,11 @@ bool SS7Layer3::buildRoutes(const NamedList& params)
 	unsigned int prio = 0;
 	unsigned int shift = 0;
 	bool local = false;
-	if (ns->name() == "local")
+	if (ns->name() == YSTRING("local"))
 	    local = true;
-	else if (ns->name() == "route")
+	else if (ns->name() == YSTRING("route"))
 	    prio = 100;
-	else if (ns->name() != "adjacent")
+	else if (ns->name() != YSTRING("adjacent"))
 	    continue;
 	// Get & check the route
 	ObjList* route = ns->split(',',true);
@@ -431,7 +431,7 @@ SS7Route* SS7Layer3::findRoute(SS7PointCode::Type type, unsigned int packed)
 void SS7Layer3::printRoutes()
 {
     String s;
-    bool router = getObject("SS7Router") != 0;
+    bool router = getObject(YSTRING("SS7Router")) != 0;
     for (unsigned int i = 0; i < YSS7_PCTYPE_COUNT; i++) {
 	ObjList* o = m_route[i].skipNull();
 	if (!o)
@@ -495,7 +495,7 @@ SS7MTP3::SS7MTP3(const NamedList& params)
     // Set point code type for each network indicator
     static const unsigned char ni[4] = { SS7MSU::International,
 	SS7MSU::SpareInternational, SS7MSU::National, SS7MSU::ReservedNational };
-    String stype = params.getValue("netind2pctype");
+    String stype = params.getValue(YSTRING("netind2pctype"));
     int level = DebugAll;
     if (stype.find(',') >= 0) {
 	ObjList* obj = stype.split(',',false);
@@ -522,10 +522,10 @@ SS7MTP3::SS7MTP3(const NamedList& params)
     }
     Debug(this,level,"Point code types are '%s' [%p]",stype.safe(),this);
 
-    m_inhibit = !params.getBoolValue("autostart",true);
-    m_checklinks = params.getBoolValue("checklinks",m_checklinks);
-    m_forcealign = params.getBoolValue("forcealign",m_forcealign);
-    int check = params.getIntValue("checkfails",5000);
+    m_inhibit = !params.getBoolValue(YSTRING("autostart"),true);
+    m_checklinks = params.getBoolValue(YSTRING("checklinks"),m_checklinks);
+    m_forcealign = params.getBoolValue(YSTRING("forcealign"),m_forcealign);
+    int check = params.getIntValue(YSTRING("checkfails"),5000);
     if (check > 0) {
 	if (check < 4000)
 	    check = 4000;
@@ -533,7 +533,7 @@ SS7MTP3::SS7MTP3(const NamedList& params)
 	    check = 12000;
 	m_checkT1 = 1000 * check;
     }
-    check = params.getIntValue("maintenance",60000);
+    check = params.getIntValue(YSTRING("maintenance"),60000);
     if (check > 0) {
 	if (check < 30000)
 	    check = 30000;
@@ -563,7 +563,7 @@ SS7MTP3::SS7MTP3(const NamedList& params)
 	}
 	TelEngine::destruct(l);
     }
-    setDumper(params.getValue("layer3dump"));
+    setDumper(params.getValue(YSTRING("layer3dump")));
 }
 
 SS7MTP3::~SS7MTP3()
@@ -791,8 +791,8 @@ bool SS7MTP3::control(Operation oper, NamedList* params)
 {
     bool ok = operational();
     if (params) {
-	m_checklinks = params->getBoolValue("checklinks",m_checklinks);
-	m_forcealign = params->getBoolValue("forcealign",m_forcealign);
+	m_checklinks = params->getBoolValue(YSTRING("checklinks"),m_checklinks);
+	m_forcealign = params->getBoolValue(YSTRING("forcealign"),m_forcealign);
     }
     switch (oper) {
 	case Pause:
@@ -816,7 +816,7 @@ bool SS7MTP3::control(Operation oper, NamedList* params)
 		    SS7Layer3::notify(-1);
 	    }
 	    m_warnDown = true;
-	    if (params && params->getBoolValue("emergency")) {
+	    if (params && params->getBoolValue(YSTRING("emergency"))) {
 		unsigned int cnt = 0;
 		const ObjList* l = &m_links;
 		for (; l; l = l->next()) {
@@ -838,14 +838,14 @@ bool SS7MTP3::control(Operation oper, NamedList* params)
 
 bool SS7MTP3::control(NamedList& params)
 {
-    String* ret = params.getParam("completion");
-    const String* oper = params.getParam("operation");
-    const char* cmp = params.getValue("component");
+    String* ret = params.getParam(YSTRING("completion"));
+    const String* oper = params.getParam(YSTRING("operation"));
+    const char* cmp = params.getValue(YSTRING("component"));
     int cmd = oper ? oper->toInteger(s_dict_control,-1) : -1;
     if (ret) {
 	if (oper && (cmd < 0))
 	    return false;
-	String part = params.getValue("partword");
+	String part = params.getValue(YSTRING("partword"));
 	if (cmp) {
 	    if (toString() != cmp)
 		return false;
@@ -872,17 +872,17 @@ bool SS7MTP3::initialize(const NamedList* config)
     Debug(this,DebugInfo,"SS7MTP3::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
     if (config)
-	debugLevel(config->getIntValue("debuglevel_mtp3",
-	    config->getIntValue("debuglevel",-1)));
+	debugLevel(config->getIntValue(YSTRING("debuglevel_mtp3"),
+	    config->getIntValue(YSTRING("debuglevel"),-1)));
     countLinks();
     m_warnDown = true;
     if (config && (0 == m_total)) {
-	m_checklinks = config->getBoolValue("checklinks",m_checklinks);
-	m_forcealign = config->getBoolValue("forcealign",m_forcealign);
+	m_checklinks = config->getBoolValue(YSTRING("checklinks"),m_checklinks);
+	m_forcealign = config->getBoolValue(YSTRING("forcealign"),m_forcealign);
 	unsigned int n = config->length();
 	for (unsigned int i = 0; i < n; i++) {
 	    NamedString* param = config->getParam(i);
-	    if (!(param && param->name() == "link"))
+	    if (!(param && param->name() == YSTRING("link")))
 		continue;
 	    NamedPointer* ptr = YOBJECT(NamedPointer,param);
 	    NamedList* linkConfig = ptr ? YOBJECT(NamedList,ptr->userData()) : 0;
@@ -913,7 +913,7 @@ bool SS7MTP3::initialize(const NamedList* config)
 		detach(link);
 	    TelEngine::destruct(link);
 	}
-	m_inhibit = !config->getBoolValue("autostart",true);
+	m_inhibit = !config->getBoolValue(YSTRING("autostart"),true);
     }
     SS7Layer3::initialize(config);
     return 0 != m_total;
diff --git a/libs/ysig/layer4.cpp b/libs/ysig/layer4.cpp
index d82df0a9..177200e8 100644
--- a/libs/ysig/layer4.cpp
+++ b/libs/ysig/layer4.cpp
@@ -43,11 +43,11 @@ unsigned char SS7Layer4::getSIO(const NamedList& params, unsigned char sif, unsi
 	prio <<= 4;
     if ((ni & 0xc0) == 0)
 	ni <<= 6;
-    sif = params.getIntValue("service",sif & 0x0f);
-    prio = SS7MSU::getPriority(params.getValue("priority"),prio & 0x30);
+    sif = params.getIntValue(YSTRING("service"),sif & 0x0f);
+    prio = SS7MSU::getPriority(params.getValue(YSTRING("priority")),prio & 0x30);
     if ((prio & 0x30) == 0)
 	prio <<= 4;
-    ni = SS7MSU::getNetIndicator(params.getValue("netindicator"),ni & 0xc0);
+    ni = SS7MSU::getNetIndicator(params.getValue(YSTRING("netindicator")),ni & 0xc0);
     if ((ni & 0xc0) == 0)
 	ni <<= 6;
     return (sif & 0x0f) | (prio & 0x30) | (ni & 0xc0);
@@ -58,14 +58,14 @@ bool SS7Layer4::initialize(const NamedList* config)
     if (engine() && !network()) {
 	NamedList params("ss7router");
 	if (config) {
-	    String name = config->getValue("router",params);
+	    String name = config->getValue(YSTRING("router"),params);
 	    if (name && !name.toBoolean(false))
 		static_cast<String&>(params) = name;
 	}
 	if (params.toBoolean(true))
 	    attach(YOBJECT(SS7Router,engine()->build("SS7Router",params,true)));
 	else if (config) {
-	    String name = config->getValue("network");
+	    String name = config->getValue(YSTRING("network"));
 	    if (name && name.toBoolean(true)) {
 		static_cast<String&>(params) = name;
 		attach(YOBJECT(SS7Layer3,engine()->build("SS7Layer3",params,true)));
@@ -87,7 +87,7 @@ void SS7Layer4::attach(SS7Layer3* network)
 	const char* name = 0;
 	if (!engine() || engine()->find(tmp)) {
 	    name = tmp->toString().safe();
-	    if (tmp->getObject("SS7Router"))
+	    if (tmp->getObject(YSTRING("SS7Router")))
 		(static_cast<SS7Router*>(tmp))->detach(this);
 	    else
 		tmp->attach(0);
diff --git a/libs/ysig/management.cpp b/libs/ysig/management.cpp
index 7de1e31d..2ea6c592 100644
--- a/libs/ysig/management.cpp
+++ b/libs/ysig/management.cpp
@@ -312,9 +312,9 @@ SS7Management::SS7Management(const NamedList& params, unsigned char sio)
       SS7Layer4(sio,&params),
       m_changeMsgs(true), m_changeSets(false), m_neighbours(true)
 {
-    m_changeMsgs = params.getBoolValue("changemsgs",m_changeMsgs);
-    m_changeSets = params.getBoolValue("changesets",m_changeSets);
-    m_neighbours = params.getBoolValue("neighbours",m_neighbours);
+    m_changeMsgs = params.getBoolValue(YSTRING("changemsgs"),m_changeMsgs);
+    m_changeSets = params.getBoolValue(YSTRING("changesets"),m_changeSets);
+    m_neighbours = params.getBoolValue(YSTRING("neighbours"),m_neighbours);
 }
 
 
@@ -387,7 +387,7 @@ HandledMSU SS7Management::receivedMSU(const SS7MSU& msu, const SS7Label& label,
 	case SS7MsgSNM::MIM:
 	    {
 		// for ANSI the SLC is not stored in SLS but in a separate field
-		int slc = msg->params().getIntValue("slc",-1);
+		int slc = msg->params().getIntValue(YSTRING("slc"),-1);
 		if (slc >= 0 && slc <= 255)
 		    lbl.setSls((unsigned char)slc);
 	    }
@@ -405,7 +405,7 @@ HandledMSU SS7Management::receivedMSU(const SS7MSU& msu, const SS7Label& label,
 	msg->type() == SS7MsgSNM::TFC ||
 	msg->type() == SS7MsgSNM::RST ||
 	msg->type() == SS7MsgSNM::RSR) {
-	String dest = msg->params().getValue("destination");
+	String dest = msg->params().getValue(YSTRING("destination"));
 	if (!dest.null()) {
 	    const char* oper = lookup(msg->type(),s_dict_control);
 	    Debug(this,DebugInfo,"%s (label=%s): Traffic %s to dest=%s [%p]",
@@ -451,9 +451,9 @@ HandledMSU SS7Management::receivedMSU(const SS7MSU& msu, const SS7Label& label,
 	    return true;
 	if (inhibit(lbl,SS7Layer2::Inactive)) {
 	    String link;
-	    link << msg->params().getValue("pointcodetype") << "," << lbl;
+	    link << msg->params().getValue(YSTRING("pointcodetype")) << "," << lbl;
 	    Debug(this,DebugNote,"Changeover order on %s",link.c_str());
-	    int seq = msg->params().getIntValue("sequence",-1);
+	    int seq = msg->params().getIntValue(YSTRING("sequence"),-1);
 	    if (seq >= 0)
 		recover(lbl,seq);
 	    seq = router ? router->getSequence(lbl) : -1;
@@ -477,7 +477,7 @@ HandledMSU SS7Management::receivedMSU(const SS7MSU& msu, const SS7Label& label,
 			}
 			break;
 		    case SS7PointCode::ANSI:
-			data[1] = (unsigned char)((msg->params().getIntValue("slc",sls) & 0x0f) | (seq << 4));
+			data[1] = (unsigned char)((msg->params().getIntValue(YSTRING("slc"),sls) & 0x0f) | (seq << 4));
 			data[2] = (unsigned char)(seq >> 4);
 			len++;
 			if (len >= 5) {
@@ -529,10 +529,10 @@ HandledMSU SS7Management::receivedMSU(const SS7MSU& msu, const SS7Label& label,
 	unlock();
 	if (pend) {
 	    String link;
-	    link << msg->params().getValue("pointcodetype") << "," << *pend;
+	    link << msg->params().getValue(YSTRING("pointcodetype")) << "," << *pend;
 	    Debug(this,DebugNote,"Changeover acknowledged on %s",link.c_str());
 	    inhibit(*pend,SS7Layer2::Inactive);
-	    int seq = msg->params().getIntValue("sequence",-1);
+	    int seq = msg->params().getIntValue(YSTRING("sequence"),-1);
 	    if (seq >= 0)
 		recover(*pend,seq);
 	}
@@ -551,7 +551,7 @@ HandledMSU SS7Management::receivedMSU(const SS7MSU& msu, const SS7Label& label,
 	    return true;
 	if (inhibit(lbl,0,SS7Layer2::Inactive)) {
 	    String link;
-	    link << msg->params().getValue("pointcodetype") << "," << lbl;
+	    link << msg->params().getValue(YSTRING("pointcodetype")) << "," << lbl;
 	    Debug(this,DebugNote,"Changeback declaration on %s",link.c_str());
 	    SS7MSU answer(msu.getSIO(),lbl,0,len+1);
 	    unsigned char* d = answer.getData(lbl.length()+1,len+1);
@@ -588,7 +588,7 @@ HandledMSU SS7Management::receivedMSU(const SS7MSU& msu, const SS7Label& label,
 	unlock();
 	if (pend) {
 	    String link;
-	    link << msg->params().getValue("pointcodetype") << "," << *pend;
+	    link << msg->params().getValue(YSTRING("pointcodetype")) << "," << *pend;
 	    Debug(this,DebugNote,"Changeback acknowledged on %s",link.c_str());
 	    inhibit(*pend,0,SS7Layer2::Inactive);
 	}
@@ -714,15 +714,15 @@ HandledMSU SS7Management::receivedMSU(const SS7MSU& msu, const SS7Label& label,
     }
     else if (msg->type() == SS7MsgSNM::UPU) {
 	Debug(this,DebugNote,"Unavailable part %s at %s, cause %s",
-	    msg->params().getValue("part","?"),
-	    msg->params().getValue("destination","?"),
-	    msg->params().getValue("cause","?"));
+	    msg->params().getValue(YSTRING("part"),"?"),
+	    msg->params().getValue(YSTRING("destination"),"?"),
+	    msg->params().getValue(YSTRING("cause"),"?"));
 	if (router) {
-	    unsigned char part = msg->params().getIntValue("part",-1);
-	    unsigned char cause = msg->params().getIntValue("cause",-1);
+	    unsigned char part = msg->params().getIntValue(YSTRING("part"),-1);
+	    unsigned char cause = msg->params().getIntValue(YSTRING("cause"),-1);
 	    SS7PointCode pc;
 	    if (part > SS7MSU::MTNS && part <= 0x0f && cause <= 0x0f &&
-		pc.assign(msg->params().getValue("destination"),label.type()))
+		pc.assign(msg->params().getValue(YSTRING("destination")),label.type()))
 		router->receivedUPU(label.type(),pc,(SS7MSU::Services)part,
 		    cause,label,sls);
 	}
@@ -750,9 +750,9 @@ HandledMSU SS7Management::receivedMSU(const SS7MSU& msu, const SS7Label& label,
 
 bool SS7Management::control(NamedList& params)
 {
-    String* ret = params.getParam("completion");
-    const String* oper = params.getParam("operation");
-    const char* cmp = params.getValue("component");
+    String* ret = params.getParam(YSTRING("completion"));
+    const String* oper = params.getParam(YSTRING("operation"));
+    const char* cmp = params.getValue(YSTRING("component"));
     int cmd = -1;
     if (!TelEngine::null(oper)) {
 	cmd = oper->toInteger(s_dict_control,cmd);
@@ -763,7 +763,7 @@ bool SS7Management::control(NamedList& params)
     if (ret) {
 	if (oper && (cmd < 0))
 	    return false;
-	String part = params.getValue("partword");
+	String part = params.getValue(YSTRING("partword"));
 	if (cmp) {
 	    if (toString() != cmp)
 		return false;
@@ -777,10 +777,10 @@ bool SS7Management::control(NamedList& params)
     if (!(cmp && toString() == cmp))
 	return false;
 
-    m_changeMsgs = params.getBoolValue("changemsgs",m_changeMsgs);
-    m_changeSets = params.getBoolValue("changesets",m_changeSets);
-    m_neighbours = params.getBoolValue("neighbours",m_neighbours);
-    const String* addr = params.getParam("address");
+    m_changeMsgs = params.getBoolValue(YSTRING("changemsgs"),m_changeMsgs);
+    m_changeSets = params.getBoolValue(YSTRING("changesets"),m_changeSets);
+    m_neighbours = params.getBoolValue(YSTRING("neighbours"),m_neighbours);
+    const String* addr = params.getParam(YSTRING("address"));
     if (cmd < 0 || TelEngine::null(addr))
 	return SignallingComponent::control(params);
     // TYPE,opc,dpc,sls,spare
@@ -818,7 +818,7 @@ bool SS7Management::control(NamedList& params)
 		case SS7MsgSNM::LFU:
 		    txSls = (txSls + 1) & 0xff;
 	    }
-	    txSls = params.getIntValue("linksel",txSls) & 0xff;
+	    txSls = params.getIntValue(YSTRING("linksel"),txSls) & 0xff;
 	    String tmp;
 	    tmp << SS7PointCode::lookup(lbl.type()) << "," << lbl;
 	    Debug(this,DebugAll,"Sending %s to %s on %d [%p]",
@@ -832,7 +832,7 @@ bool SS7Management::control(NamedList& params)
 		case SS7MsgSNM::RST:
 		case SS7MsgSNM::RSR:
 		    {
-			addr = params.getParam("destination");
+			addr = params.getParam(YSTRING("destination"));
 			SS7PointCode dest(opc);
 			if (TelEngine::null(addr) || dest.assign(*addr,t)) {
 			    unsigned char data[5];
@@ -878,12 +878,12 @@ bool SS7Management::control(NamedList& params)
 		case SS7MsgSNM::COA:
 		case SS7MsgSNM::XCO:
 		case SS7MsgSNM::XCA:
-		    if (params.getBoolValue("emergency",false)) {
+		    if (params.getBoolValue(YSTRING("emergency"),false)) {
 			unsigned char data = (SS7MsgSNM::COO == cmd) ? SS7MsgSNM::ECO : SS7MsgSNM::ECA;
 			return transmitMSU(SS7MSU(txSio,lbl,&data,1),lbl,txSls) >= 0;
 		    }
 		    else {
-			int seq = params.getIntValue("sequence",0) & 0x00ffffff;
+			int seq = params.getIntValue(YSTRING("sequence"),0) & 0x00ffffff;
 			if (SS7MsgSNM::COO == cmd || SS7MsgSNM::COA == cmd)
 			    seq &= 0x7f;
 			int len = 2;
@@ -899,7 +899,7 @@ bool SS7Management::control(NamedList& params)
 				}
 				break;
 			    case SS7PointCode::ANSI:
-				data[1] = (unsigned char)((params.getIntValue("slc",sls) & 0x0f) | (seq << 4));
+				data[1] = (unsigned char)((params.getIntValue(YSTRING("slc"),sls) & 0x0f) | (seq << 4));
 				data[2] = (unsigned char)(seq >> 4);
 				len = 3;
 				if (SS7MsgSNM::XCO == cmd || SS7MsgSNM::XCA == cmd) {
@@ -920,7 +920,7 @@ bool SS7Management::control(NamedList& params)
 		case SS7MsgSNM::CBD:
 		case SS7MsgSNM::CBA:
 		    {
-			int code = params.getIntValue("code",0);
+			int code = params.getIntValue(YSTRING("code"),0);
 			int len = 2;
 			unsigned char data[3];
 			data[0] = cmd;
@@ -929,7 +929,7 @@ bool SS7Management::control(NamedList& params)
 				data[1] = (unsigned char)code;
 				break;
 			    case SS7PointCode::ANSI:
-				data[1] = (unsigned char)((params.getIntValue("slc",sls) & 0x0f) | (code << 4));
+				data[1] = (unsigned char)((params.getIntValue(YSTRING("slc"),sls) & 0x0f) | (code << 4));
 				data[2] = (unsigned char)(code >> 4);
 				len = 3;
 				break;
diff --git a/libs/ysig/q921.cpp b/libs/ysig/q921.cpp
index dd206815..0a54720e 100644
--- a/libs/ysig/q921.cpp
+++ b/libs/ysig/q921.cpp
@@ -54,7 +54,7 @@ static inline const char* linkSide(bool net)
 static inline void fixParams(NamedList& params, const NamedList& config)
 {
     params.copyParams(config);
-    int rx = params.getIntValue("rxunderrun");
+    int rx = params.getIntValue(YSTRING("rxunderrun"));
     if ((rx > 0) && (rx < 2500))
 	params.setParam("rxunderrun","2500");
 }
@@ -143,11 +143,11 @@ ISDNQ921::ISDNQ921(const NamedList& params, const char* name, ISDNQ921Management
     m_idleTimer.interval(params,"t203",2000,10000,false);
     // Adjust idle timeout to data link side
     m_idleTimer.interval(m_idleTimer.interval() + (network() ? -500 : 500));
-    m_window.maxVal(params.getIntValue("maxpendingframes",7));
+    m_window.maxVal(params.getIntValue(YSTRING("maxpendingframes"),7));
     if (!m_window.maxVal())
 	m_window.maxVal(7);
-    setDebug(params.getBoolValue("print-frames",false),
-	params.getBoolValue("extended-debug",false));
+    setDebug(params.getBoolValue(YSTRING("print-frames"),false),
+	params.getBoolValue(YSTRING("extended-debug"),false));
     if (debugAt(DebugInfo)) {
 	String tmp;
 #ifdef DEBUG
@@ -168,7 +168,7 @@ ISDNQ921::ISDNQ921(const NamedList& params, const char* name, ISDNQ921Management
 	    linkSide(network()),tmp.safe(),this);
     }
     if (!mgmt)
-	setDumper(params.getValue("layer2dump"));
+	setDumper(params.getValue(YSTRING("layer2dump")));
 }
 
 // Destructor
@@ -195,15 +195,15 @@ bool ISDNQ921::initialize(const NamedList* config)
     Debug(this,DebugInfo,"ISDNQ921::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
     if (config) {
-	debugLevel(config->getIntValue("debuglevel_q921",
-	    config->getIntValue("debuglevel",-1)));
-	setDebug(config->getBoolValue("print-frames",false),
-	    config->getBoolValue("extended-debug",false));
+	debugLevel(config->getIntValue(YSTRING("debuglevel_q921"),
+	    config->getIntValue(YSTRING("debuglevel"),-1)));
+	setDebug(config->getBoolValue(YSTRING("print-frames"),false),
+	    config->getBoolValue(YSTRING("extended-debug"),false));
     }
     if (config && !m_management && !iface()) {
-	NamedString* name = config->getParam("sig");
+	NamedString* name = config->getParam(YSTRING("sig"));
 	if (!name)
-	    name = config->getParam("basename");
+	    name = config->getParam(YSTRING("basename"));
 	if (name) {
 	    NamedPointer* ptr = YOBJECT(NamedPointer,name);
 	    NamedList* ifConfig = ptr ? YOBJECT(NamedList,ptr->userData()) : 0;
@@ -1043,7 +1043,7 @@ ISDNQ921Management::ISDNQ921Management(const NamedList& params, const char* name
     m_network = net;
     m_teiManTimer.interval(params,"t202",2500,2600,false);
     m_teiTimer.interval(params,"t201",1000,5000,false);
-    setDumper(params.getValue("layer2dump"));
+    setDumper(params.getValue(YSTRING("layer2dump")));
     bool set0 = true;
     if (baseName.endsWith("Management")) {
 	baseName = baseName.substr(0,baseName.length()-10);
@@ -1087,12 +1087,12 @@ bool ISDNQ921Management::initialize(const NamedList* config)
     Debug(this,DebugInfo,"ISDNQ921Management::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
     if (config)
-	debugLevel(config->getIntValue("debuglevel_q921mgmt",
-	    config->getIntValue("debuglevel",-1)));
+	debugLevel(config->getIntValue(YSTRING("debuglevel_q921mgmt"),
+	    config->getIntValue(YSTRING("debuglevel"),-1)));
     if (config && !iface()) {
-	NamedString* name = config->getParam("sig");
+	NamedString* name = config->getParam(YSTRING("sig"));
 	if (!name)
-	    name = config->getParam("basename");
+	    name = config->getParam(YSTRING("basename"));
 	if (name) {
 	    NamedPointer* ptr = YOBJECT(NamedPointer,name);
 	    NamedList* ifConfig = ptr ? YOBJECT(NamedList,ptr->userData()) : 0;
@@ -1512,8 +1512,8 @@ ISDNQ921Passive::ISDNQ921Passive(const NamedList& params, const char* name)
 #endif
     m_idleTimer.interval(params,"idletimeout",4000,30000,false);
     m_checkLinkSide = detectType();
-    setDebug(params.getBoolValue("print-frames",false),
-	params.getBoolValue("extended-debug",false));
+    setDebug(params.getBoolValue(YSTRING("print-frames"),false),
+	params.getBoolValue(YSTRING("extended-debug"),false));
     DDebug(this,DebugInfo,
 	"ISDN Passive Data Link type=%s autodetect=%s idle-timeout=%u [%p]",
 	linkSide(network()),String::boolText(detectType()),
@@ -1521,7 +1521,7 @@ ISDNQ921Passive::ISDNQ921Passive(const NamedList& params, const char* name)
     m_idleTimer.start();
     // Try to dump from specific parameter, fall back to generic
     const char* dump = network() ? "layer2dump-net" : "layer2dump-cpe";
-    setDumper(params.getValue(dump,params.getValue("layer2dump")));
+    setDumper(params.getValue(dump,params.getValue(YSTRING("layer2dump"))));
 }
 
 // Destructor
@@ -1546,15 +1546,15 @@ bool ISDNQ921Passive::initialize(const NamedList* config)
     Debug(this,DebugInfo,"ISDNQ921Passive::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
     if (config) {
-	debugLevel(config->getIntValue("debuglevel_q921",
-	    config->getIntValue("debuglevel",-1)));
-	setDebug(config->getBoolValue("print-frames",false),
-	    config->getBoolValue("extended-debug",false));
+	debugLevel(config->getIntValue(YSTRING("debuglevel_q921"),
+	    config->getIntValue(YSTRING("debuglevel"),-1)));
+	setDebug(config->getBoolValue(YSTRING("print-frames"),false),
+	    config->getBoolValue(YSTRING("extended-debug"),false));
     }
     if (config && !iface()) {
-	NamedString* name = config->getParam("sig");
+	NamedString* name = config->getParam(YSTRING("sig"));
 	if (!name)
-	    name = config->getParam("basename");
+	    name = config->getParam(YSTRING("basename"));
 	if (name) {
 	    NamedPointer* ptr = YOBJECT(NamedPointer,name);
 	    NamedList* ifConfig = ptr ? YOBJECT(NamedList,ptr->userData()) : 0;
@@ -1759,15 +1759,15 @@ ISDNLayer2::ISDNLayer2(const NamedList& params, const char* name, u_int8_t tei)
       m_maxUserData(260)
 {
     XDebug(this,DebugAll,"ISDNLayer2 '%s' comp=%p [%p]",name,static_cast<const SignallingComponent*>(this),this);
-    m_network = params.getBoolValue("network",false);
-    m_detectType = params.getBoolValue("detect",false);
-    int tmp = params.getIntValue("sapi",0);
+    m_network = params.getBoolValue(YSTRING("network"),false);
+    m_detectType = params.getBoolValue(YSTRING("detect"),false);
+    int tmp = params.getIntValue(YSTRING("sapi"),0);
     m_sapi = (tmp >= 0 && tmp <= Q921_SAPI_MANAGEMENT) ? tmp : 0;
-    tmp = params.getIntValue("tei",tei);
+    tmp = params.getIntValue(YSTRING("tei"),tei);
     m_tei = (tmp >= 0 && tmp < Q921_TEI_BROADCAST) ? tmp : 0;
     teiAssigned(true);
-    m_autoRestart = params.getBoolValue("auto-restart",true);
-    m_maxUserData = params.getIntValue("maxuserdata",260);
+    m_autoRestart = params.getBoolValue(YSTRING("auto-restart"),true);
+    m_maxUserData = params.getIntValue(YSTRING("maxuserdata"),260);
     if (!m_maxUserData)
 	m_maxUserData = 260;
 }
diff --git a/libs/ysig/q931.cpp b/libs/ysig/q931.cpp
index a9c56b2b..f6bfe32d 100644
--- a/libs/ysig/q931.cpp
+++ b/libs/ysig/q931.cpp
@@ -341,10 +341,10 @@ bool ISDNQ931IEData::processBearerCaps(ISDNQ931Message* msg, bool add,
 	m_transferRate = "";
 	return false;
     }
-    m_transferCapability = ie->getValue("transfer-cap");
-    m_transferMode = ie->getValue("transfer-mode");
-    m_transferRate = ie->getValue("transfer-rate");
-    m_format = ie->getValue("layer1-protocol");
+    m_transferCapability = ie->getValue(YSTRING("transfer-cap"));
+    m_transferMode = ie->getValue(YSTRING("transfer-mode"));
+    m_transferRate = ie->getValue(YSTRING("transfer-rate"));
+    m_format = ie->getValue(YSTRING("layer1-protocol"));
     return true;
 }
 
@@ -370,11 +370,11 @@ bool ISDNQ931IEData::processChannelID(ISDNQ931Message* msg, bool add,
 	m_channelMandatory = m_channelByNumber = false;
 	return false;
     }
-    m_bri = ie->getBoolValue("interface-bri",m_bri);
-    m_channelMandatory = ie->getBoolValue("channel-exclusive");
-    m_channelByNumber = ie->getBoolValue("channel-by-number");
-    m_channelType = ie->getValue("type");
-    m_channelSelect = ie->getValue("channel-select");
+    m_bri = ie->getBoolValue(YSTRING("interface-bri"),m_bri);
+    m_channelMandatory = ie->getBoolValue(YSTRING("channel-exclusive"));
+    m_channelByNumber = ie->getBoolValue(YSTRING("channel-by-number"));
+    m_channelType = ie->getValue(YSTRING("type"));
+    m_channelSelect = ie->getValue(YSTRING("channel-select"));
     if (m_bri && m_channelSelect) {
 	m_channelByNumber = true;
 	if (m_channelSelect == "b1")
@@ -389,12 +389,12 @@ bool ISDNQ931IEData::processChannelID(ISDNQ931Message* msg, bool add,
 	unsigned int n = ie->length();
 	for (unsigned int i = 0; i < n; i++) {
 	    NamedString* ns = ie->getParam(i);
-	    if (ns && (ns->name() == "channels"))
+	    if (ns && (ns->name() == YSTRING("channels")))
 		m_channels.append(*ns,",");
 	}
     }
     else
-	m_channels = ie->getValue("slot-map");
+	m_channels = ie->getValue(YSTRING("slot-map"));
     return true;
 }
 
@@ -418,7 +418,7 @@ bool ISDNQ931IEData::processProgress(ISDNQ931Message* msg, bool add,
 	// Progress may repeat
 	ISDNQ931IE* ie = msg->getIE(ISDNQ931IE::Progress);
 	for (; ie; ie = msg->getIE(ISDNQ931IE::Progress,ie))
-	    m_progress.append(ie->getValue("description"),",");
+	    m_progress.append(ie->getValue(YSTRING("description")),",");
     }
     return !m_progress.null();
 }
@@ -474,9 +474,9 @@ bool ISDNQ931IEData::processCalledNo(ISDNQ931Message* msg, bool add,
 	m_calledNo = "";
 	return false;
     }
-    m_calledNo = ie->getValue("number");
-    m_calledType = ie->getValue("type");
-    m_calledPlan = ie->getValue("plan");
+    m_calledNo = ie->getValue(YSTRING("number"));
+    m_calledType = ie->getValue(YSTRING("type"));
+    m_calledPlan = ie->getValue(YSTRING("plan"));
     return true;
 }
 
@@ -510,11 +510,11 @@ bool ISDNQ931IEData::processCallingNo(ISDNQ931Message* msg, bool add,
 	m_callerNo = "";
 	return false;
     }
-    m_callerNo = ie->getValue("number");
-    m_callerType = ie->getValue("type");
-    m_callerPlan = ie->getValue("plan");
-    m_callerPres = ie->getValue("presentation");
-    m_callerScreening = ie->getValue("screening");
+    m_callerNo = ie->getValue(YSTRING("number"));
+    m_callerType = ie->getValue(YSTRING("type"));
+    m_callerPlan = ie->getValue(YSTRING("plan"));
+    m_callerPres = ie->getValue(YSTRING("presentation"));
+    m_callerScreening = ie->getValue(YSTRING("screening"));
     return true;
 }
 
@@ -839,7 +839,7 @@ bool ISDNQ931Call::sendEvent(SignallingEvent* event)
 		default:
 		    m_terminate = m_destroy = true;
 		    retVal = sendReleaseComplete(event->message() ?
-			event->message()->params().getValue("reason") : 0);
+			event->message()->params().getValue(YSTRING("reason")) : 0);
 		    break;
 	    }
 	    break;
@@ -948,9 +948,9 @@ SignallingEvent* ISDNQ931Call::getEvent(const Time& when)
 // Get reserved circuit or this object
 void* ISDNQ931Call::getObject(const String& name) const
 {
-    if (name == "SignallingCircuit")
+    if (name == YSTRING("SignallingCircuit"))
 	return m_circuit;
-    if (name == "ISDNQ931Call")
+    if (name == YSTRING("ISDNQ931Call"))
 	return (void*)this;
     return SignallingCall::getObject(name);
 }
@@ -1448,9 +1448,9 @@ bool ISDNQ931Call::sendAlerting(SignallingMessage* sigMsg)
     MSG_CHECK_SEND(ISDNQ931Message::Alerting)
     const char* format = 0;
     if (sigMsg) {
-	format = sigMsg->params().getValue("format");
+	format = sigMsg->params().getValue(YSTRING("format"));
 	m_inbandAvailable = m_inbandAvailable ||
-	    sigMsg->params().getBoolValue("earlymedia",false);
+	    sigMsg->params().getBoolValue(YSTRING("earlymedia"),false);
 	if (m_inbandAvailable)
 	    SignallingUtils::appendFlag(m_data.m_progress,"in-band-info");
     }
@@ -1526,7 +1526,7 @@ bool ISDNQ931Call::sendConnect(SignallingMessage* sigMsg)
     }
     // Progress indicator
     if (sigMsg) {
-	m_data.m_progress = sigMsg->params().getValue("call-progress");
+	m_data.m_progress = sigMsg->params().getValue(YSTRING("call-progress"));
 	m_data.processProgress(msg,true,&q931()->parserData());
     }
     m_conTimer.start();
@@ -1543,7 +1543,7 @@ bool ISDNQ931Call::sendConnectAck(SignallingMessage* sigMsg)
     ISDNQ931Message* msg = new ISDNQ931Message(ISDNQ931Message::ConnectAck,this);
     // Progress indicator
     if (sigMsg) {
-	m_data.m_progress = sigMsg->params().getValue("call-progress");
+	m_data.m_progress = sigMsg->params().getValue(YSTRING("call-progress"));
 	m_data.processProgress(msg,true,&q931()->parserData());
     }
     else
@@ -1558,7 +1558,7 @@ bool ISDNQ931Call::sendDisconnect(SignallingMessage* sigMsg)
     MSG_CHECK_SEND(ISDNQ931Message::Disconnect)
     m_data.m_reason = "";
     if (sigMsg)
-	m_data.m_reason = sigMsg->params().getValue("reason");
+	m_data.m_reason = sigMsg->params().getValue(YSTRING("reason"));
     ISDNQ931Message* msg = new ISDNQ931Message(ISDNQ931Message::Disconnect,this);
     m_data.processCause(msg,true);
     changeState(DisconnectReq);
@@ -1575,12 +1575,12 @@ bool ISDNQ931Call::sendInfo(SignallingMessage* sigMsg)
     MSG_CHECK_SEND(ISDNQ931Message::Info)
     ISDNQ931Message* msg = new ISDNQ931Message(ISDNQ931Message::Info,this);
     // Check send complete complete
-    if (sigMsg->params().getBoolValue("complete"))
+    if (sigMsg->params().getBoolValue(YSTRING("complete")))
 	msg->appendSafe(new ISDNQ931IE(ISDNQ931IE::SendComplete));
-    m_data.m_display = sigMsg->params().getValue("display");
+    m_data.m_display = sigMsg->params().getValue(YSTRING("display"));
     m_data.processDisplay(msg,true,&q931()->parserData());
     // Check tones or ringing
-    const char* tone = sigMsg->params().getValue("tone");
+    const char* tone = sigMsg->params().getValue(YSTRING("tone"));
     if (tone)
 	msg->appendIEValue(ISDNQ931IE::Keypad,"keypad",tone);
     return q931()->sendMessage(msg,callTei());
@@ -1592,9 +1592,9 @@ bool ISDNQ931Call::sendProgress(SignallingMessage* sigMsg)
 {
     MSG_CHECK_SEND(ISDNQ931Message::Progress)
     if (sigMsg) {
-	m_data.m_progress = sigMsg->params().getValue("progress");
+	m_data.m_progress = sigMsg->params().getValue(YSTRING("progress"));
 	m_inbandAvailable = m_inbandAvailable ||
-	    sigMsg->params().getBoolValue("earlymedia",false);
+	    sigMsg->params().getBoolValue(YSTRING("earlymedia"),false);
 	if (m_inbandAvailable)
 	    SignallingUtils::appendFlag(m_data.m_progress,"in-band-info");
     }
@@ -1611,7 +1611,7 @@ bool ISDNQ931Call::sendRelease(const char* reason, SignallingMessage* sigMsg)
 	return false;
     // Get reason
     if (!reason && sigMsg)
-	reason = sigMsg->params().getValue("reason",0);
+	reason = sigMsg->params().getValue(YSTRING("reason"),0);
     if (reason)
 	m_data.m_reason = reason;
     m_terminate = true;
@@ -1661,7 +1661,7 @@ bool ISDNQ931Call::sendSetup(SignallingMessage* sigMsg)
 	m_data.m_transferCapability = "speech";
 	m_data.m_transferMode = "circuit";
 	m_data.m_transferRate = "64kbit";
-	m_data.m_format = sigMsg->params().getValue("format",q931()->format());
+	m_data.m_format = sigMsg->params().getValue(YSTRING("format"),q931()->format());
 	if (0xffff == lookup(m_data.m_format,Q931Parser::s_dict_bearerProto1,0xffff))
 	    m_data.m_format = "alaw";
 	m_data.processBearerCaps(msg,true);
@@ -1693,22 +1693,22 @@ bool ISDNQ931Call::sendSetup(SignallingMessage* sigMsg)
 	    m_data.processChannelID(msg,true);
 	}
 	// Progress indicator
-	m_data.m_progress = sigMsg->params().getValue("call-progress");
+	m_data.m_progress = sigMsg->params().getValue(YSTRING("call-progress"));
 	m_data.processProgress(msg,true,&q931()->parserData());
 	// Display
-	m_data.m_display = sigMsg->params().getValue("callername");
+	m_data.m_display = sigMsg->params().getValue(YSTRING("callername"));
 	m_data.processDisplay(msg,true,&q931()->parserData());
 	// CallingNo
-	m_data.m_callerType = sigMsg->params().getValue("callernumtype",q931()->numType());
-	m_data.m_callerPlan = sigMsg->params().getValue("callernumplan",q931()->numPlan());
-	m_data.m_callerPres = sigMsg->params().getValue("callerpres",q931()->numPresentation());
-	m_data.m_callerScreening = sigMsg->params().getValue("callerscreening",q931()->numScreening());
-	m_data.m_callerNo = sigMsg->params().getValue("caller");
+	m_data.m_callerType = sigMsg->params().getValue(YSTRING("callernumtype"),q931()->numType());
+	m_data.m_callerPlan = sigMsg->params().getValue(YSTRING("callernumplan"),q931()->numPlan());
+	m_data.m_callerPres = sigMsg->params().getValue(YSTRING("callerpres"),q931()->numPresentation());
+	m_data.m_callerScreening = sigMsg->params().getValue(YSTRING("callerscreening"),q931()->numScreening());
+	m_data.m_callerNo = sigMsg->params().getValue(YSTRING("caller"));
 	m_data.processCallingNo(msg,true);
 	// CalledNo
-	m_data.m_calledType = sigMsg->params().getValue("callednumtype");
-	m_data.m_calledPlan = sigMsg->params().getValue("callednumplan");
-	m_data.m_calledNo = sigMsg->params().getValue("called");
+	m_data.m_calledType = sigMsg->params().getValue(YSTRING("callednumtype"));
+	m_data.m_calledPlan = sigMsg->params().getValue(YSTRING("callednumplan"));
+	m_data.m_calledNo = sigMsg->params().getValue(YSTRING("called"));
 	m_data.processCalledNo(msg,true);
 	// Send
 	changeState(CallInitiated);
@@ -1731,7 +1731,7 @@ bool ISDNQ931Call::sendSetup(SignallingMessage* sigMsg)
 bool ISDNQ931Call::sendSuspendRej(const char* reason, SignallingMessage* sigMsg)
 {
     if (!reason && sigMsg)
-	reason = sigMsg->params().getValue("reason");
+	reason = sigMsg->params().getValue(YSTRING("reason"));
     ISDNQ931Message* msg = new ISDNQ931Message(ISDNQ931Message::SuspendRej,this);
     msg->appendIEValue(ISDNQ931IE::Cause,0,reason);
     return q931()->sendMessage(msg,callTei());
@@ -1790,7 +1790,7 @@ SignallingEvent* ISDNQ931Call::getCircuitEvent(const Time& when)
     SignallingEvent* event = 0;
     switch (ev->type()) {
 	case SignallingCircuitEvent::Dtmf: {
-	    const char* tone = ev->getValue("tone");
+	    const char* tone = ev->getValue(YSTRING("tone"));
 	    if (!(tone && *tone))
 		break;
 	    ISDNQ931Message* msg = new ISDNQ931Message(ISDNQ931Message::Info,this);
@@ -2021,11 +2021,11 @@ void ISDNQ931CallMonitor::setTerminate(const char* reason)
 // Get caller's and called's circuit or this object
 void* ISDNQ931CallMonitor::getObject(const String& name) const
 {
-    if (name == "SignallingCircuitCaller")
+    if (name == YSTRING("SignallingCircuitCaller"))
 	return m_callerCircuit;
-    if (name == "SignallingCircuitCalled")
+    if (name == YSTRING("SignallingCircuitCalled"))
 	return m_calledCircuit;
-    if (name == "ISDNQ931CallMonitor")
+    if (name == YSTRING("ISDNQ931CallMonitor"))
 	return (void*)this;
     return SignallingCall::getObject(name);
 }
@@ -2200,7 +2200,7 @@ SignallingEvent* ISDNQ931CallMonitor::getCircuitEvent(const Time& when)
     SignallingEvent* event = 0;
     switch (ev->type()) {
 	case SignallingCircuitEvent::Dtmf: {
-	    const char* tone = ev->getValue("tone");
+	    const char* tone = ev->getValue(YSTRING("tone"));
 	    if (!(tone && *tone))
 		break;
 	    ISDNQ931Message* msg = new ISDNQ931Message(ISDNQ931Message::Info,
@@ -2295,14 +2295,14 @@ ISDNQ931ParserData::ISDNQ931ParserData(const NamedList& params, DebugEnabler* db
     m_flags(0),
     m_flagsOrig(0)
 {
-    m_allowSegment = params.getBoolValue("allowsegmentation",false);
-    m_maxSegments = params.getIntValue("maxsegments",8);
-    m_maxDisplay = params.getIntValue("max-display",34);
+    m_allowSegment = params.getBoolValue(YSTRING("allowsegmentation"),false);
+    m_maxSegments = params.getIntValue(YSTRING("maxsegments"),8);
+    m_maxDisplay = params.getIntValue(YSTRING("max-display"),34);
     if (m_maxDisplay != 34 && m_maxDisplay != 82)
 	m_maxDisplay = 34;
-    m_extendedDebug = params.getBoolValue("extended-debug",false);
+    m_extendedDebug = params.getBoolValue(YSTRING("extended-debug"),false);
     // Set flags
-    String flags = params.getValue("switchtype");
+    String flags = params.getValue(YSTRING("switchtype"));
     SignallingUtils::encodeFlags(0,m_flagsOrig,flags,ISDNQ931::s_swType);
     SignallingUtils::encodeFlags(0,m_flagsOrig,flags,ISDNQ931::s_flags);
     m_flags = m_flagsOrig;
@@ -2379,9 +2379,9 @@ ISDNQ931::ISDNQ931(const NamedList& params, const char* name)
     }
 #endif
     m_parserData.m_dbg = this;
-    m_networkHint = params.getBoolValue("network",m_networkHint);
-    m_data.m_bri = !(m_primaryRate = params.getBoolValue("primary",m_primaryRate));
-    m_callRefLen = params.getIntValue("callreflen",m_primaryRate ? 2 : 1);
+    m_networkHint = params.getBoolValue(YSTRING("network"),m_networkHint);
+    m_data.m_bri = !(m_primaryRate = params.getBoolValue(YSTRING("primary"),m_primaryRate));
+    m_callRefLen = params.getIntValue(YSTRING("callreflen"),m_primaryRate ? 2 : 1);
     if (m_callRefLen < 1 || m_callRefLen > 4)
 	m_callRefLen = 2;
     // Set mask. Bit 7 of the first byte of the message header it's used for initiator flag
@@ -2394,25 +2394,25 @@ ISDNQ931::ISDNQ931(const NamedList& params, const char* name)
     m_callDiscTimer.interval(params,"t305",0,5000,false);
     m_callRelTimer.interval(params,"t308",0,5000,false);
     m_callConTimer.interval(params,"t313",0,5000,false);
-    m_cpeNumber = params.getValue("number");
-    m_numPlan = params.getValue("numplan");
+    m_cpeNumber = params.getValue(YSTRING("number"));
+    m_numPlan = params.getValue(YSTRING("numplan"));
     if (0xffff == lookup(m_numPlan,Q931Parser::s_dict_numPlan,0xffff))
 	m_numPlan = "unknown";
-    m_numType = params.getValue("numtype");
+    m_numType = params.getValue(YSTRING("numtype"));
     if (0xffff == lookup(m_numType,Q931Parser::s_dict_typeOfNumber,0xffff))
 	m_numType = "unknown";
-    m_numPresentation = params.getValue("presentation");
+    m_numPresentation = params.getValue(YSTRING("presentation"));
     if (0xffff == lookup(m_numPresentation,Q931Parser::s_dict_presentation,0xffff))
 	m_numPresentation = "allowed";
-    m_numScreening = params.getValue("screening");
+    m_numScreening = params.getValue(YSTRING("screening"));
     if (0xffff == lookup(m_numScreening,Q931Parser::s_dict_screening,0xffff))
 	m_numScreening = "user-provided";
-    m_format = params.getValue("format");
+    m_format = params.getValue(YSTRING("format"));
     if (0xffff == lookup(m_format,Q931Parser::s_dict_bearerProto1,0xffff))
 	m_format = "alaw";
     // Debug
-    setDebug(params.getBoolValue("print-messages",false),
-	params.getBoolValue("extended-debug",false));
+    setDebug(params.getBoolValue(YSTRING("print-messages"),false),
+	params.getBoolValue(YSTRING("extended-debug"),false));
     if (debugAt(DebugInfo)) {
 	String s(network() ? "NET" : "CPE");
 #ifdef DEBUG
@@ -2437,14 +2437,14 @@ ISDNQ931::ISDNQ931(const NamedList& params, const char* name)
 	s << " segmentation=" << String::boolText(m_parserData.m_allowSegment);
 	s << " max-segments=" << (unsigned int)m_parserData.m_maxSegments;
 #else
-	s << " type=" << params.getValue("switchtype");
+	s << " type=" << params.getValue(YSTRING("switchtype"));
 	s << " pri=" << String::boolText(m_primaryRate);
 	s << " format=" << m_format;
 	s << " channelsync=" << String::boolText(0 != m_syncGroupTimer.interval());
 #endif
 	Debug(this,DebugInfo,"ISDN Call Controller %s [%p]",s.c_str(),this);
     }
-    setDumper(params.getValue("layer3dump"));
+    setDumper(params.getValue(YSTRING("layer3dump")));
     m_syncGroupTimer.start();
 }
 
@@ -2469,13 +2469,13 @@ bool ISDNQ931::initialize(const NamedList* config)
     Debug(this,DebugInfo,"ISDNQ931::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
     if (config) {
-	debugLevel(config->getIntValue("debuglevel_q931",
-	    config->getIntValue("debuglevel",-1)));
-	setDebug(config->getBoolValue("print-messages",false),
-	    config->getBoolValue("extended-debug",false));
+	debugLevel(config->getIntValue(YSTRING("debuglevel_q931"),
+	    config->getIntValue(YSTRING("debuglevel"),-1)));
+	setDebug(config->getBoolValue(YSTRING("print-messages"),false),
+	    config->getBoolValue(YSTRING("extended-debug"),false));
     }
     if (config && !layer2()) {
-	const String* name = config->getParam("sig");
+	const String* name = config->getParam(YSTRING("sig"));
 	if (!name)
 	    name = config;
 	if (!TelEngine::null(name)) {
@@ -2728,7 +2728,7 @@ void ISDNQ931::receiveData(const DataBlock& data, u_int8_t tei, ISDNLayer2* laye
 		// We are a BRI CPE with a number - check the called party field
 		ISDNQ931IE* ie = msg->getIE(ISDNQ931IE::CalledNo);
 		if (ie) {
-		    const String* number = ie->getParam("number");
+		    const String* number = ie->getParam(YSTRING("number"));
 		    if (number && !number->startsWith(m_cpeNumber)) {
 			DDebug(this,DebugInfo,"Setup was for '%s', not us.",number->c_str());
 			break;
@@ -3043,12 +3043,12 @@ ISDNQ931Message* ISDNQ931::getMsg(const DataBlock& data)
 	ISDNQ931IE* ie = msg->getIE(ISDNQ931IE::Segmented);
 	if (!ie)
 	    break;
-	NamedString* ns = ie->getParam("first");
+	NamedString* ns = ie->getParam(YSTRING("first"));
 	if (!ns)
 	    break;
 	first = ns->toBoolean();
-	remaining = (u_int8_t)ie->getIntValue("remaining",0xff);
-	type = (u_int8_t)ie->getIntValue("message",0xff);
+	remaining = (u_int8_t)ie->getIntValue(YSTRING("remaining"),0xff);
+	type = (u_int8_t)ie->getIntValue(YSTRING("message"),0xff);
 	valid = true;
 	break;
     }
@@ -3196,7 +3196,7 @@ void ISDNQ931::processMsgRestart(ISDNQ931Message* msg, u_int8_t tei)
 	msg->name(),m_data.m_restart.c_str(),m_data.m_channels.c_str());
 
     while (true) {
-	if (m_data.m_restart == "channels") {
+	if (m_data.m_restart == YSTRING("channels")) {
 	    if (list->count() > 0)
 		terminateCalls(list,"resource-unavailable");
 	    else {
@@ -3206,8 +3206,8 @@ void ISDNQ931::processMsgRestart(ISDNQ931Message* msg, u_int8_t tei)
 	    break;
 	}
 
-	bool single = (m_data.m_restart == "interface");
-	bool all = !single && (m_data.m_restart == "all-interfaces");
+	bool single = (m_data.m_restart == YSTRING("interface"));
+	bool all = !single && (m_data.m_restart == YSTRING("all-interfaces"));
 	// If all interfaces is specified, ChannelID must not be present
 	// If ChannelID is present and allowed, it must contain a single channel code
 	if (!(single || all) || (all && list->count() > 0) ||
@@ -3460,8 +3460,8 @@ ISDNQ931Monitor::ISDNQ931Monitor(const NamedList& params, const char* name)
     m_parserData.m_maxMsgLen = 0xffffffff;
     m_parserData.m_dbg = this;
     // Debug
-    setDebug(params.getBoolValue("print-messages",true),
-	params.getBoolValue("extended-debug",false));
+    setDebug(params.getBoolValue(YSTRING("print-messages"),true),
+	params.getBoolValue(YSTRING("extended-debug"),false));
 }
 
 ISDNQ931Monitor::~ISDNQ931Monitor()
@@ -3485,10 +3485,10 @@ bool ISDNQ931Monitor::initialize(const NamedList* config)
     Debug(this,DebugInfo,"ISDNQ931Monitor::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
     if (config) {
-	debugLevel(config->getIntValue("debuglevel_q931",
-	    config->getIntValue("debuglevel",-1)));
-	setDebug(config->getBoolValue("print-messages",false),
-	    config->getBoolValue("extended-debug",false));
+	debugLevel(config->getIntValue(YSTRING("debuglevel_q931"),
+	    config->getIntValue(YSTRING("debuglevel"),-1)));
+	setDebug(config->getBoolValue(YSTRING("print-messages"),false),
+	    config->getBoolValue(YSTRING("extended-debug"),false));
 	for (int i = 0; i <= 1; i++) {
 	    bool net = (0 == i);
 	    if (net && m_q921Net)
@@ -4044,7 +4044,7 @@ void ISDNQ931Message::toString(String& dest, bool extendedDebug, const char* ind
 
 void* ISDNQ931Message::getObject(const String& name) const
 {
-    if (name == "ISDNQ931Message")
+    if (name == YSTRING("ISDNQ931Message"))
 	return (void*)this;
     return SignallingMessage::getObject(name);
 }
@@ -4594,7 +4594,7 @@ ISDNQ931Message* Q931Parser::decode(const DataBlock& buffer, DataBlock* segData)
 	    if (m_settings->flag(ISDNQ931::IgnoreNonLockedIE)) {
 		bool ignore = false;
 		if (ie->type() == ISDNQ931IE::Shift)
-		    ignore = m_skip = !ie->getBoolValue("lock",false);
+		    ignore = m_skip = !ie->getBoolValue(YSTRING("lock"),false);
 		else if (m_skip) {
 		    ignore = true;
 		    m_skip = false;
@@ -5074,8 +5074,8 @@ ISDNQ931IE* Q931Parser::getIE(const u_int8_t* data, u_int32_t len, u_int32_t& co
 // Check Shift IE. Change current codeset
 void Q931Parser::shiftCodeset(const ISDNQ931IE* ie)
 {
-    bool locking = ie->getBoolValue("lock",false);
-    int value = ie->getIntValue("codeset",0);
+    bool locking = ie->getBoolValue(YSTRING("lock"),false);
+    int value = ie->getIntValue(YSTRING("codeset"),0);
     XDebug(m_settings->m_dbg,DebugAll,
 	"Process %s shift with codeset %u [%p]",
 	locking?"locking":"non locking",value,m_msg);
diff --git a/libs/ysig/router.cpp b/libs/ysig/router.cpp
index 56ea377a..f8d01b16 100644
--- a/libs/ysig/router.cpp
+++ b/libs/ysig/router.cpp
@@ -337,20 +337,20 @@ SS7Router::SS7Router(const NamedList& params)
 	    &params,this,tmp.c_str());
     }
 #endif
-    const String* tr = params.getParam("transfer");
+    const String* tr = params.getParam(YSTRING("transfer"));
     if (!TelEngine::null(tr)) {
-	m_transferSilent = (*tr == "silent");
+	m_transferSilent = (*tr == YSTRING("silent"));
 	m_transfer = !m_transferSilent && tr->toBoolean();
     }
-    m_autoAllowed = params.getBoolValue("autoallow",m_autoAllowed);
-    m_sendUnavail = params.getBoolValue("sendupu",m_sendUnavail);
-    m_sendProhibited = params.getBoolValue("sendtfp",m_sendProhibited);
+    m_autoAllowed = params.getBoolValue(YSTRING("autoallow"),m_autoAllowed);
+    m_sendUnavail = params.getBoolValue(YSTRING("sendupu"),m_sendUnavail);
+    m_sendProhibited = params.getBoolValue(YSTRING("sendtfp"),m_sendProhibited);
     m_restart.interval(params,"starttime",5000,(m_transfer ? 60000 : 10000),false);
     m_isolate.interval(params,"isolation",500,1000,true);
     m_routeTest.interval(params,"testroutes",10000,50000,true),
     m_trafficOk.interval(m_restart.interval() + 4000);
     m_trafficSent.interval(m_restart.interval() + 8000);
-    m_testRestricted = params.getBoolValue("testrestricted",m_testRestricted);
+    m_testRestricted = params.getBoolValue(YSTRING("testrestricted"),m_testRestricted);
     loadLocalPC(params);
 }
 
@@ -369,18 +369,18 @@ bool SS7Router::initialize(const NamedList* config)
     Debug(this,DebugInfo,"SS7Router::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
     if (config) {
-	debugLevel(config->getIntValue("debuglevel_router",
-	    config->getIntValue("debuglevel",-1)));
-	const String* tr = config->getParam("transfer");
+	debugLevel(config->getIntValue(YSTRING("debuglevel_router"),
+	    config->getIntValue(YSTRING("debuglevel"),-1)));
+	const String* tr = config->getParam(YSTRING("transfer"));
 	if (!TelEngine::null(tr)) {
-	    m_transferSilent = (*tr == "silent");
+	    m_transferSilent = (*tr == YSTRING("silent"));
 	    m_transfer = !m_transferSilent && tr->toBoolean(m_transfer);
 	}
-	setNI(SS7MSU::getNetIndicator(config->getValue("netindicator"),SS7MSU::National));
-	m_autoAllowed = config->getBoolValue("autoallow",m_autoAllowed);
-	m_sendUnavail = config->getBoolValue("sendupu",m_sendUnavail);
-	m_sendProhibited = config->getBoolValue("sendtfp",m_sendProhibited);
-	const String* param = config->getParam("management");
+	setNI(SS7MSU::getNetIndicator(config->getValue(YSTRING("netindicator")),SS7MSU::National));
+	m_autoAllowed = config->getBoolValue(YSTRING("autoallow"),m_autoAllowed);
+	m_sendUnavail = config->getBoolValue(YSTRING("sendupu"),m_sendUnavail);
+	m_sendProhibited = config->getBoolValue(YSTRING("sendtfp"),m_sendProhibited);
+	const String* param = config->getParam(YSTRING("management"));
 	const char* name = "ss7snm";
 	if (param) {
 	    if (*param && !param->toBoolean(false))
@@ -402,7 +402,7 @@ bool SS7Router::initialize(const NamedList* config)
 	    attach(m_mngmt = YSIGCREATE(SS7Management,&params));
 	}
     }
-    return m_started || (config && !config->getBoolValue("autostart")) || restart();
+    return m_started || (config && !config->getBoolValue(YSTRING("autostart"))) || restart();
 }
 
 void SS7Router::loadLocalPC(const NamedList& params)
@@ -1765,9 +1765,9 @@ void SS7Router::notify(SS7Layer3* network, int sls)
 
 bool SS7Router::control(NamedList& params)
 {
-    String* ret = params.getParam("completion");
-    const String* oper = params.getParam("operation");
-    const char* cmp = params.getValue("component");
+    String* ret = params.getParam(YSTRING("completion"));
+    const String* oper = params.getParam(YSTRING("operation"));
+    const char* cmp = params.getValue(YSTRING("component"));
     int cmd = -1;
     if (!TelEngine::null(oper))
 	cmd = oper->toInteger(s_dict_control,cmd);
@@ -1775,7 +1775,7 @@ bool SS7Router::control(NamedList& params)
     if (ret) {
 	if (oper && (cmd < 0))
 	    return false;
-	String part = params.getValue("partword");
+	String part = params.getValue(YSTRING("partword"));
 	if (cmp) {
 	    if (toString() != cmp)
 		return false;
@@ -1789,9 +1789,9 @@ bool SS7Router::control(NamedList& params)
     if (!(cmp && toString() == cmp))
 	return false;
 
-    m_autoAllowed = params.getBoolValue("autoallow",m_autoAllowed);
-    m_sendUnavail = params.getBoolValue("sendupu",m_sendUnavail);
-    m_sendProhibited = params.getBoolValue("sendtfp",m_sendProhibited);
+    m_autoAllowed = params.getBoolValue(YSTRING("autoallow"),m_autoAllowed);
+    m_sendUnavail = params.getBoolValue(YSTRING("sendupu"),m_sendUnavail);
+    m_sendProhibited = params.getBoolValue(YSTRING("sendtfp"),m_sendProhibited);
     String err;
     switch (cmd) {
 	case SS7Router::Pause:
@@ -1826,12 +1826,12 @@ bool SS7Router::control(NamedList& params)
 	case SS7MsgSNM::TFR:
 	case SS7MsgSNM::TFA:
 	    {
-		SS7PointCode::Type type = SS7PointCode::lookup(params.getValue("pointcodetype"));
+		SS7PointCode::Type type = SS7PointCode::lookup(params.getValue(YSTRING("pointcodetype")));
 		if (SS7PointCode::length(type) == 0) {
 		    err << "missing 'pointcodetype'";
 		    break;
 		}
-		const String* dest = params.getParam("destination");
+		const String* dest = params.getParam(YSTRING("destination"));
 		if (TelEngine::null(dest)) {
 		    err << "missing 'destination'";
 		    break;
@@ -1842,9 +1842,9 @@ bool SS7Router::control(NamedList& params)
 		    break;
 		}
 		if (SS7MsgSNM::RST == cmd || SS7MsgSNM::RSR == cmd) {
-		    const String* addr = params.getParam("back-address");
+		    const String* addr = params.getParam(YSTRING("back-address"));
 		    if (TelEngine::null(addr))
-			addr = params.getParam("address");
+			addr = params.getParam(YSTRING("address"));
 		    if (TelEngine::null(addr)) {
 			err = "missing 'address'";
 			break;
@@ -1876,9 +1876,9 @@ bool SS7Router::control(NamedList& params)
 		    m_mngmt->controlExecute(ctl);
 		    return true;
 		}
-		String src = params.getParam("source");
+		String src = params.getParam(YSTRING("source"));
 		if (src.null()) {
-		    const String* addr = params.getParam("address");
+		    const String* addr = params.getParam(YSTRING("address"));
 		    if (addr) {
 			ObjList* l = addr->split(',');
 			if (l && l->at(1))
@@ -1889,18 +1889,18 @@ bool SS7Router::control(NamedList& params)
 		if (src) {
 		    SS7PointCode opc;
 		    if (!opc.assign(src,type)) {
-			if (!params.getBoolValue("automatic"))
+			if (!params.getBoolValue(YSTRING("automatic")))
 			    err << "invalid source: " << src ;
 			break;
 		    }
 		    if (!setRouteSpecificState(type,pc,opc,routeState(static_cast<SS7MsgSNM::Type>(cmd)))) {
-			if (!params.getBoolValue("automatic"))
+			if (!params.getBoolValue(YSTRING("automatic")))
 			    err << "no such route: " << *dest << " from: " << src;
 			break;
 		    }
 		}
 		else if (!setRouteState(type,pc,routeState(static_cast<SS7MsgSNM::Type>(cmd)))) {
-		    if (!params.getBoolValue("automatic"))
+		    if (!params.getBoolValue(YSTRING("automatic")))
 			err << "no such route: " << *dest;
 		    break;
 		}
diff --git a/libs/ysig/sigcall.cpp b/libs/ysig/sigcall.cpp
index 369c1d53..8422b5ce 100644
--- a/libs/ysig/sigcall.cpp
+++ b/libs/ysig/sigcall.cpp
@@ -75,13 +75,13 @@ SignallingCallControl::SignallingCallControl(const NamedList& params,
       m_exiting(false)
 {
     // Controller location
-    m_location = params.getValue("location");
+    m_location = params.getValue(YSTRING("location"));
     // Strategy
-    const char* strategy = params.getValue("strategy","increment");
+    const char* strategy = params.getValue(YSTRING("strategy"),"increment");
     m_strategy = SignallingCircuitGroup::str2strategy(strategy);
     String restrict;
     if (m_strategy != SignallingCircuitGroup::Random)
-	restrict = params.getValue("strategy-restrict");
+	restrict = params.getValue(YSTRING("strategy-restrict"));
     if (!restrict.null()) {
 	if (restrict == "odd")
 	    m_strategy |= SignallingCircuitGroup::OnlyOdd;
@@ -94,14 +94,14 @@ SignallingCallControl::SignallingCallControl(const NamedList& params,
     }
 
     // Message prefix
-    m_msgPrefix = params.getValue("message-prefix",msgPrefix);
+    m_msgPrefix = params.getValue(YSTRING("message-prefix"),msgPrefix);
 
     // Verify event timer
     m_verifyTimer.interval(params,"verifyeventinterval",10,120,true,true);
     m_verifyTimer.start();
 
     // Media Required
-    m_mediaRequired = (MediaRequired)params.getIntValue("needmedia",
+    m_mediaRequired = (MediaRequired)params.getIntValue(YSTRING("needmedia"),
 	s_mediaRequired,m_mediaRequired);
 }
 
@@ -789,7 +789,7 @@ SignallingCircuitSpan* SignallingCircuitGroup::buildSpan(const String& name, uns
 	    : NamedList(name), m_group(group)
 	    { }
 	virtual void* getObject(const String& name) const
-	    { return (name == "SignallingCircuitGroup") ? m_group : NamedList::getObject(name); }
+	    { return (name == YSTRING("SignallingCircuitGroup")) ? m_group : NamedList::getObject(name); }
 	SignallingCircuitGroup* m_group;
     };
 
@@ -1174,15 +1174,15 @@ AnalogLine::AnalogLine(AnalogLineGroup* grp, unsigned int cic, const NamedList&
     if (m_type == Recorder)
 	m_type = FXO;
     m_address << m_group->toString() << "/" << m_circuit->code();
-    m_inband = params.getBoolValue("dtmfinband",false);
-    String tmp = params.getValue("echocancel");
+    m_inband = params.getBoolValue(YSTRING("dtmfinband"),false);
+    String tmp = params.getValue(YSTRING("echocancel"));
     if (tmp.isBoolean())
 	m_echocancel = tmp.toBoolean() ? 1 : -1;
-    m_answerOnPolarity = params.getBoolValue("answer-on-polarity",false);
-    m_hangupOnPolarity = params.getBoolValue("hangup-on-polarity",false);
-    m_polarityControl = params.getBoolValue("polaritycontrol",false);
+    m_answerOnPolarity = params.getBoolValue(YSTRING("answer-on-polarity"),false);
+    m_hangupOnPolarity = params.getBoolValue(YSTRING("hangup-on-polarity"),false);
+    m_polarityControl = params.getBoolValue(YSTRING("polaritycontrol"),false);
 
-    m_callSetup = (CallSetupInfo)lookup(params.getValue("callsetup"),csNames(),After);
+    m_callSetup = (CallSetupInfo)lookup(params.getValue(YSTRING("callsetup")),csNames(),After);
 
     m_callSetupTimeout = getValidInt(params,"callsetup-timeout",2000);
     m_noRingTimeout = getValidInt(params,"ring-timeout",10000);
@@ -1192,9 +1192,9 @@ AnalogLine::AnalogLine(AnalogLineGroup* grp, unsigned int cic, const NamedList&
     DDebug(m_group,DebugAll,"AnalogLine() addr=%s type=%s [%p]",
 	address(),lookup(m_type,typeNames()),this);
 
-    if (!params.getBoolValue("out-of-service",false)) {
+    if (!params.getBoolValue(YSTRING("out-of-service"),false)) {
 	resetCircuit();
-	if (params.getBoolValue("connect",true))
+	if (params.getBoolValue(YSTRING("connect"),true))
 	    connect(false);
     }
     else
diff --git a/libs/ysig/sigtran.cpp b/libs/ysig/sigtran.cpp
index 52ba926d..e57ff7eb 100644
--- a/libs/ysig/sigtran.cpp
+++ b/libs/ysig/sigtran.cpp
@@ -282,9 +282,9 @@ bool SIGAdaptation::initialize(const NamedList* config)
 {
     if (transport())
 	return true;
-    NamedString* name = config->getParam("sig");
+    NamedString* name = config->getParam(YSTRING("sig"));
     if (!name)
-	name = config->getParam("basename");
+	name = config->getParam(YSTRING("basename"));
     if (name) {
 	DDebug(this,DebugInfo,"Creating transport for SIGTRAN UA [%p]",this);
 	NamedPointer* ptr = YOBJECT(NamedPointer,name);
@@ -513,8 +513,8 @@ SIGAdaptClient::SIGAdaptClient(const char* name, const NamedList* params,
 	Debug(this,DebugInfo,"SIGAdaptClient(%u,%u) created [%p]%s",
 	    payload,port,this,tmp.c_str());
 #endif
-	m_aspId = params->getIntValue("aspid",m_aspId);
-	m_traffic = (TrafficMode)params->getIntValue("traffic",s_trafficModes,m_traffic);
+	m_aspId = params->getIntValue(YSTRING("aspid"),m_aspId);
+	m_traffic = (TrafficMode)params->getIntValue(YSTRING("traffic"),s_trafficModes,m_traffic);
     }
 }
 
@@ -861,7 +861,7 @@ SS7M2PA::SS7M2PA(const NamedList& params)
     // Confirmation timer 1/2 t4
     m_confTimer.interval(params,"conf_timer",50,400,false);
     // Maximum unacknowledged messages, max_unack+1 will force an ACK
-    m_maxUnack = params.getIntValue("max_unack",4);
+    m_maxUnack = params.getIntValue(YSTRING("max_unack"),4);
     if (m_maxUnack > 10)
 	m_maxUnack = 10;
     DDebug(this,DebugAll,"Creating SS7M2PA [%p]",this);
@@ -882,13 +882,13 @@ bool SS7M2PA::initialize(const NamedList* config)
 	config->dump(tmp,"\r\n  ",'\'',true);
     Debug(this,DebugInfo,"SS7M2PA::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
-    m_dumpMsg = config && config->getBoolValue("dumpMsg",false);
-    m_autostart = !config || config->getBoolValue("autostart",true);
-    m_autoEmergency = !config || config->getBoolValue("autoemergency",true);
+    m_dumpMsg = config && config->getBoolValue(YSTRING("dumpMsg"),false);
+    m_autostart = !config || config->getBoolValue(YSTRING("autostart"),true);
+    m_autoEmergency = !config || config->getBoolValue(YSTRING("autoemergency"),true);
     if (config && !transport()) {
-	NamedString* name = config->getParam("sig");
+	NamedString* name = config->getParam(YSTRING("sig"));
 	if (!name)
-	    name = config->getParam("basename");
+	    name = config->getParam(YSTRING("basename"));
 	if (name) {
 	    NamedPointer* ptr = YOBJECT(NamedPointer,name);
 	    NamedList* trConfig = ptr ? YOBJECT(NamedList,ptr->userData()) : 0;
@@ -1178,9 +1178,9 @@ unsigned int SS7M2PA::status() const
 bool SS7M2PA::control(Operation oper, NamedList* params)
 {
     if (params) {
-	m_autostart = params->getBoolValue("autostart",m_autostart);
-	m_autoEmergency = params->getBoolValue("autoemergency",m_autoEmergency);
-	m_maxUnack = params->getIntValue("max_unack",m_maxUnack);
+	m_autostart = params->getBoolValue(YSTRING("autostart"),m_autostart);
+	m_autoEmergency = params->getBoolValue(YSTRING("autoemergency"),m_autoEmergency);
+	m_maxUnack = params->getIntValue(YSTRING("max_unack"),m_maxUnack);
 	if (m_maxUnack > 10)
 	    m_maxUnack = 10;
     }
@@ -1498,12 +1498,13 @@ bool SS7M2UAClient::processMSG(unsigned char msgVersion, unsigned char msgClass,
 SS7M2UA::SS7M2UA(const NamedList& params)
     : SignallingComponent(params.safe("SS7M2UA"),&params),
       m_retrieve(50),
-      m_iid(params.getIntValue("iid",-1)), m_linkState(LinkDown), m_rpo(false),
+      m_iid(params.getIntValue(YSTRING("iid"),-1)),
+      m_linkState(LinkDown), m_rpo(false),
       m_longSeq(false)
 {
     DDebug(DebugInfo,"Creating SS7M2UA [%p]",this);
     m_retrieve.interval(params,"retrieve",5,200,true);
-    m_longSeq = params.getBoolValue("longsequence");
+    m_longSeq = params.getBoolValue(YSTRING("longsequence"));
     m_lastSeqRx = -2;
 }
 
@@ -1515,13 +1516,13 @@ bool SS7M2UA::initialize(const NamedList* config)
 	config->dump(tmp,"\r\n  ",'\'',true);
     Debug(this,DebugInfo,"SS7M2UA::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
-    m_autostart = !config || config->getBoolValue("autostart",true);
-    m_autoEmergency = !config || config->getBoolValue("autoemergency",true);
+    m_autostart = !config || config->getBoolValue(YSTRING("autostart"),true);
+    m_autoEmergency = !config || config->getBoolValue(YSTRING("autoemergency"),true);
     if (config && !adaptation()) {
-	m_iid = config->getIntValue("iid",m_iid);
-	NamedString* name = config->getParam("client");
+	m_iid = config->getIntValue(YSTRING("iid"),m_iid);
+	NamedString* name = config->getParam(YSTRING("client"));
 	if (!name)
-	    name = config->getParam("basename");
+	    name = config->getParam(YSTRING("basename"));
 	if (name) {
 	    DDebug(this,DebugInfo,"Creating adaptation '%s' for SS7 M2UA [%p]",
 		name->c_str(),this);
@@ -1550,9 +1551,9 @@ bool SS7M2UA::initialize(const NamedList* config)
 bool SS7M2UA::control(Operation oper, NamedList* params)
 {
     if (params) {
-	m_autostart = params->getBoolValue("autostart",m_autostart);
-	m_autoEmergency = params->getBoolValue("autoemergency",m_autoEmergency);
-	m_longSeq = params->getBoolValue("longsequence",m_longSeq);
+	m_autostart = params->getBoolValue(YSTRING("autostart"),m_autostart);
+	m_autoEmergency = params->getBoolValue(YSTRING("autoemergency"),m_autoEmergency);
+	m_longSeq = params->getBoolValue(YSTRING("longsequence"),m_longSeq);
     }
     switch (oper) {
 	case Pause:
@@ -1922,7 +1923,7 @@ bool ISDNIUAClient::processMSG(unsigned char msgVersion, unsigned char msgClass,
 ISDNIUA::ISDNIUA(const NamedList& params, const char *name, u_int8_t tei)
     : SignallingComponent(params.safe(name ? name : "ISDNIUA"),&params),
       ISDNLayer2(params,name,tei),
-      m_iid(params.getIntValue("iid",-1))
+      m_iid(params.getIntValue(YSTRING("iid"),-1))
 {
     DDebug(DebugInfo,"Creating ISDNIUA [%p]",this);
 }
@@ -2122,12 +2123,12 @@ bool ISDNIUA::initialize(const NamedList* config)
 	config->dump(tmp,"\r\n  ",'\'',true);
     Debug(this,DebugInfo,"ISDNIUA::initialize(%p) [%p]%s",config,this,tmp.c_str());
 #endif
-    m_autostart = !config || config->getBoolValue("autostart",true);
+    m_autostart = !config || config->getBoolValue(YSTRING("autostart"),true);
     if (config && !adaptation()) {
-	m_iid = config->getIntValue("iid",m_iid);
-	NamedString* name = config->getParam("client");
+	m_iid = config->getIntValue(YSTRING("iid"),m_iid);
+	NamedString* name = config->getParam(YSTRING("client"));
 	if (!name)
-	    name = config->getParam("basename");
+	    name = config->getParam(YSTRING("basename"));
 	if (name) {
 	    DDebug(this,DebugInfo,"Creating adaptation '%s' for ISDN UA [%p]",
 		name->c_str(),this);
diff --git a/libs/ysig/testpart.cpp b/libs/ysig/testpart.cpp
index d65c7b7b..d47cc93d 100644
--- a/libs/ysig/testpart.cpp
+++ b/libs/ysig/testpart.cpp
@@ -129,7 +129,7 @@ bool SS7Testing::initialize(const NamedList* config)
     Lock mylock(this);
     setParams(*config);
     bool ok = SS7Layer4::initialize(config);
-    if (ok && config->getBoolValue("autostart",false)) {
+    if (ok && config->getBoolValue(YSTRING("autostart"),false)) {
 	if (m_timer.interval() && m_lbl.length())
 	    m_timer.start();
 	sendTraffic();
@@ -139,15 +139,15 @@ bool SS7Testing::initialize(const NamedList* config)
 
 bool SS7Testing::control(NamedList& params)
 {
-    String* ret = params.getParam("completion");
-    const String* oper = params.getParam("operation");
-    const char* cmp = params.getValue("component");
+    String* ret = params.getParam(YSTRING("completion"));
+    const String* oper = params.getParam(YSTRING("operation"));
+    const char* cmp = params.getValue(YSTRING("component"));
     int cmd = oper ? oper->toInteger(s_dict_control,-1) : -1;
 
     if (ret) {
 	if (oper && (cmd < 0))
 	    return false;
-	String part = params.getValue("partword");
+	String part = params.getValue(YSTRING("partword"));
 	if (cmp) {
 	    if (toString() != cmp)
 		return false;
@@ -188,15 +188,15 @@ bool SS7Testing::control(NamedList& params)
 
 void SS7Testing::setParams(const NamedList& params, bool setSeq)
 {
-    if (!m_timer.interval() || params.getParam("interval"))
+    if (!m_timer.interval() || params.getParam(YSTRING("interval")))
 	m_timer.interval(params,"interval",20,1000,true);
-    m_len = params.getIntValue("length",m_len);
-    m_sharing = params.getBoolValue("sharing",m_sharing);
+    m_len = params.getIntValue(YSTRING("length"),m_len);
+    m_sharing = params.getBoolValue(YSTRING("sharing"),m_sharing);
     if (m_len > 1024)
 	m_len = 1024;
     if (setSeq || !m_seq)
-	m_seq = params.getIntValue("sequence",m_seq);
-    const String* lbl = params.getParam("address");
+	m_seq = params.getIntValue(YSTRING("sequence"),m_seq);
+    const String* lbl = params.getParam(YSTRING("address"));
     if (!TelEngine::null(lbl)) {
 	// TYPE,opc,dpc,sls,spare
 	SS7PointCode::Type t = SS7PointCode::Other;