diff --git a/.gitignore b/.gitignore
index 2359e46..b2c9cc4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -44,6 +44,7 @@ src/libosmocc/libosmocc.a
 src/libsample/libsample.a
 src/libfilter/libfilter.a
 src/libtimer/libtimer.a
+src/libselect/libselect.a
 src/libph_socket/libph_socket.a
 src/pstn/osmo-cc-pstn-endpoint
 
diff --git a/configure.ac b/configure.ac
index e166919..612f4b2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -86,6 +86,7 @@ AC_OUTPUT(
 	src/libfm/Makefile
 	src/libfilter/Makefile
 	src/libtimer/Makefile
+	src/libselect/Makefile
 	src/libjitter/Makefile
 	src/libosmocc/Makefile
 	src/libg711/Makefile
diff --git a/src/Makefile.am b/src/Makefile.am
index 37340b7..7eb3a09 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -9,6 +9,7 @@ SUBDIRS = \
 	libdtmf \
 	libfsk \
 	libtimer \
+	libselect \
 	libjitter \
 	libosmocc \
 	libph_socket \
diff --git a/src/pstn/Makefile.am b/src/pstn/Makefile.am
index 37973fd..276cfbd 100644
--- a/src/pstn/Makefile.am
+++ b/src/pstn/Makefile.am
@@ -20,6 +20,7 @@ osmo_cc_pstn_endpoint_LDADD = \
 	../libfm/libfm.a \
 	../libfilter/libfilter.a \
 	../libtimer/libtimer.a \
+	../libselect/libselect.a \
 	../libjitter/libjitter.a \
 	../libosmocc/libosmocc.a \
 	../libg711/libg711.a \
diff --git a/src/pstn/main.c b/src/pstn/main.c
index e77ae3a..15e6c12 100644
--- a/src/pstn/main.c
+++ b/src/pstn/main.c
@@ -386,15 +386,22 @@ int main(int argc, char *argv[])
 	signal(SIGPIPE, sighandler);
 
 	while (!quit) {
-		int w;
-		process_timer();
-		pstn_work(pstn_ep);
-		rtp_work(pstn_ep);
+		int work;
+		double timeout;
+		/* handle all handlers until done */
 		do {
-			w = 0;
-			w |= osmo_cc_handle();
-		} while (w);
-		usleep(1000);
+			work = 0;
+			work |= osmo_cc_handle();
+		} while (work);
+		/* handle all timers
+		 * timeout is 0, if there was an event
+		 * -> handle FDs without waiting, continue this loop
+		 * timeout is not 0, if there was no event
+		 * -> wait until FD or timeout
+		*/
+		timeout = process_timer();
+		/* wait for FD event until given timeout */
+		work = osmo_fd_select(timeout);
 	}
 
 	signal(SIGINT, SIG_DFL);
diff --git a/src/pstn/pstn.c b/src/pstn/pstn.c
index 374da80..52e4263 100644
--- a/src/pstn/pstn.c
+++ b/src/pstn/pstn.c
@@ -301,7 +301,7 @@ void pstn_destroy(pstn_t *pstn)
 	PDEBUG(DTEL, DEBUG_DEBUG, "PSTN instance destroyed\n");
 }
 
-static void pstn_timeout(struct timer *timer);
+static void pstn_timeout(void *data);
 void recv_dtmf(void *priv, char digit, dtmf_meas_t __attribute__((unused)) *meas);
 
 static void pstn_new_state(pstn_t *pstn, enum pstn_state state)
@@ -332,11 +332,6 @@ int pstn_init(pstn_t *pstn, const char *name, const char *socketname, const char
 	pstn->ringing_type_hold = ringing_type_hold;
 	pstn->tones_type = tones_type;
 
-	/* create ph socket */
-	rc = ph_socket_init(&pstn->ph_socket, ph_socket_rx_msg, pstn, socketname, 0);
-	if (rc < 0)
-		return rc;
-
 	/* init DTMF detector */
 	rc = dtmf_decode_init(&pstn->dtmf_dec, pstn, recv_dtmf, 8000, db2level(6.0), db2level(-30.0));
 	if (rc < 0)
@@ -365,6 +360,11 @@ int pstn_init(pstn_t *pstn, const char *name, const char *socketname, const char
 	/* bring into service */
 	pstn_new_state(pstn, PSTN_STATE_BLOCKED);
 
+	/* create ph socket here because we get a reply from the function call */
+	rc = ph_socket_init(&pstn->ph_socket, ph_socket_rx_msg, pstn, socketname, 0);
+	if (rc < 0)
+		return rc;
+
 	return 0;
 }
 
@@ -385,17 +385,6 @@ void rtp_receive(struct osmo_cc_session_codec *codec, uint8_t __attribute__((unu
 	jitter_save(&pstn->tx_dejitter, data, len, 1, sequence, timestamp, ssrc);
 }
 
-
-void rtp_work(pstn_t *pstn)
-{
-	int i;
-
-	for (i = 0; i < 2; i++) {
-		if (pstn->call[i]->cc_session)
-			osmo_cc_session_handle(pstn->call[i]->cc_session, pstn->call[i]);
-	}
-}
-
 static void dtmf_on(pstn_t *pstn)
 {
 	if (pstn->dtmf_on)
@@ -1722,14 +1711,13 @@ static void v5_disc_req_and_cleanup(pstn_t *pstn)
 		v5_send(pstn, PSTN_EVENT_DISC_REQ, NULL, 0);
 }
 
-
 /*
  * timeout
  */
 
-static void pstn_timeout(struct timer *timer)
+static void pstn_timeout(void *data)
 {
-	pstn_t *pstn = timer->priv;
+	pstn_t *pstn = data;
 
 	switch (pstn->timer_ident) {
 	case TIMER_IDENT_DIALING:
@@ -1781,12 +1769,3 @@ static void pstn_timeout(struct timer *timer)
 	}
 }
 
-/*
- * work
- */
-
-void pstn_work(pstn_t *pstn)
-{
-	ph_socket_work(&pstn->ph_socket);
-}
-
diff --git a/src/pstn/pstn.h b/src/pstn/pstn.h
index 9b79db5..4107328 100644
--- a/src/pstn/pstn.h
+++ b/src/pstn/pstn.h
@@ -1,5 +1,6 @@
 
 #include "../libtimer/timer.h"
+#include "../libselect/select.h"
 #include "../libosmocc/endpoint.h"
 #include "../libsample/sample.h"
 #include "../libjitter/jitter.h"
@@ -157,5 +158,4 @@ pstn_t *pstn_create(void);
 int pstn_init(pstn_t *pstn, const char *name, const char *socketname, const char **subscribers, int subscriber_num, uint8_t serving_location, int tx_delay, enum pstn_cid_method clip, int cid_bell, int cid_dtmf, int clip_date, int enblock, int recall, int *ringing_types_incoming, int ringing_type_hold, enum tones_type tones_type, char law);
 void cc_message(osmo_cc_endpoint_t *ep, uint32_t callref, osmo_cc_msg_t *msg);
 void rtp_work(pstn_t *pstn_ep);
-void pstn_work(pstn_t *pstn_ep);