diff --git a/src/isdn/dss1.c b/src/isdn/dss1.c
index f05bd1e..2586492 100644
--- a/src/isdn/dss1.c
+++ b/src/isdn/dss1.c
@@ -201,48 +201,54 @@ static void generate_aocs_fac(call_t *call)
 
 		LOGP(DISDN, LOGL_DEBUG, "Sending AOC-S facility from metering data: connect_units=%d unit_period_decisecs=%d\n", call->metering_connect_units, call->metering_unit_period_decisecs);
 
-		if(call->metering_connect_units == 0) {					// Free call
-			LOGP(DISDN, LOGL_DEBUG, "AOC-S currencyInfoList: BasicComm FreeOfCharge / CallSetup FreeOfCharge\n");
+		if(call->metering_connect_units == 0) {
+			/* Free call */
+			LOGP(DISDN, LOGL_DEBUG, "AOC-S currencyInfoList: BasicComm FreeOfCharge; CallSetup FreeOfCharge\n");
 			fac.u.inv.o.AOCcuril.currencyInfoCount = 2;
-			fac.u.inv.o.AOCcuril.currencyInfo[0].chargedItem = 0x00;	// basic comm
-			fac.u.inv.o.AOCcuril.currencyInfo[0].currencyType = 0x84;	// free
-			fac.u.inv.o.AOCcuril.currencyInfo[1].chargedItem = 0x02;	// call setup
-			fac.u.inv.o.AOCcuril.currencyInfo[1].currencyType = 0x84;	// free
+			fac.u.inv.o.AOCcuril.currencyInfo[0].chargedItem = 0x00;						// BasicComm
+			fac.u.inv.o.AOCcuril.currencyInfo[0].currencyType = 0x84;						// Free
+			fac.u.inv.o.AOCcuril.currencyInfo[1].chargedItem = 0x02;						// CallSetup
+			fac.u.inv.o.AOCcuril.currencyInfo[1].currencyType = 0x84;						// Free
 		}
-		else if(call->metering_unit_period_decisecs == 0) {		// CallSetup-only FlatRate
-			/* note some payphones (e.g. BluePhone) only interpret 'basic comm' charged item, therefore we don't use 'call setup' charged item */
-			LOGP(DISDN, LOGL_DEBUG, "AOC-S currencyInfoList: BasicComm FlatRate / CallSetup FlatRate\n");
+		else if(call->metering_unit_period_decisecs == 0) {
+			/* Connect-only FlatRate call; note some payphones (e.g. BluePhone) only interpret 'BasicComm' charged item, therefore we don't use 'CallSetup' charged item */
+			LOGP(DISDN, LOGL_DEBUG, "AOC-S currencyInfoList: BasicComm FlatRate %d/100 EUR; CallSetup FreeOfCharge\n", AOCS_CURRENCY_AMOUNT_PER_UNIT * call->metering_connect_units);
 			fac.u.inv.o.AOCcuril.currencyInfoCount = 2;
-			fac.u.inv.o.AOCcuril.currencyInfo[0].chargedItem = 0x00;	// basic comm
-			fac.u.inv.o.AOCcuril.currencyInfo[0].currencyType = 0xA2;	// FlatRate
+			fac.u.inv.o.AOCcuril.currencyInfo[0].chargedItem = 0x00;						// BasicComm
+			fac.u.inv.o.AOCcuril.currencyInfo[0].currencyType = 0xA2;						// FlatRate
 			strncpy((char *)fac.u.inv.o.AOCcuril.currencyInfo[0].FlatRateCurrency.currency, "EUR", 10);	// Currency value
 			fac.u.inv.o.AOCcuril.currencyInfo[0].FlatRateCurrency.currencyAmount = AOCS_CURRENCY_AMOUNT_PER_UNIT * call->metering_connect_units;
-			fac.u.inv.o.AOCcuril.currencyInfo[0].FlatRateCurrency.multiplier = 1;	// 1/100 EUR
-			fac.u.inv.o.AOCcuril.currencyInfo[1].chargedItem = 0x02;	// call setup
-			fac.u.inv.o.AOCcuril.currencyInfo[1].currencyType = 0xA2;	// FlatRate
-			strncpy((char *)fac.u.inv.o.AOCcuril.currencyInfo[0].FlatRateCurrency.currency, "EUR", 10);	// Currency value
-			fac.u.inv.o.AOCcuril.currencyInfo[1].FlatRateCurrency.currencyAmount = AOCS_CURRENCY_AMOUNT_PER_UNIT * call->metering_connect_units;
-			fac.u.inv.o.AOCcuril.currencyInfo[1].FlatRateCurrency.multiplier = 1;	// 1/100 EUR
+			fac.u.inv.o.AOCcuril.currencyInfo[0].FlatRateCurrency.multiplier = 1;			// 1/100 EUR
+			fac.u.inv.o.AOCcuril.currencyInfo[1].chargedItem = 0x02;						// CallSetup
+			fac.u.inv.o.AOCcuril.currencyInfo[1].currencyType = 0x84;						// Free
 		}
-		else {								// Normal call
-			/* note some payphones (e.g. BluePhone) only interpret 'basic comm' charged item */
-			LOGP(DISDN, LOGL_DEBUG, "AOC-S currencyInfoList: BasicComm DurationCurrency / CallSetup FlatRate\n");
+		else {
+			/* Normal call; note some payphones (e.g. BluePhone) only interpret 'BasicComm' charged item */
 			fac.u.inv.o.AOCcuril.currencyInfoCount = 2;
-			fac.u.inv.o.AOCcuril.currencyInfo[0].chargedItem = 0x00;	// basic comm
-			fac.u.inv.o.AOCcuril.currencyInfo[0].currencyType = 0xA1;	// DurationCurrency
+			fac.u.inv.o.AOCcuril.currencyInfo[0].chargedItem = 0x00;						// BasicComm
+			fac.u.inv.o.AOCcuril.currencyInfo[0].currencyType = 0xA1;						// DurationCurrency
 			strncpy((char *)fac.u.inv.o.AOCcuril.currencyInfo[0].durationCurrency.currency, "EUR", 10);	// Currency value
 			fac.u.inv.o.AOCcuril.currencyInfo[0].durationCurrency.currencyAmount = AOCS_CURRENCY_AMOUNT_PER_UNIT;
-			fac.u.inv.o.AOCcuril.currencyInfo[0].durationCurrency.multiplier = 1;	// 1/100 EUR
-			fac.u.inv.o.AOCcuril.currencyInfo[0].durationCurrency.typeOfCharging = 0x00;	// Contin. Charging
+			fac.u.inv.o.AOCcuril.currencyInfo[0].durationCurrency.multiplier = 1;			// 1/100 EUR
+			fac.u.inv.o.AOCcuril.currencyInfo[0].durationCurrency.typeOfCharging = 1;		// StepFunction
 			fac.u.inv.o.AOCcuril.currencyInfo[0].durationCurrency.durLengthTimeUnit = call->metering_unit_period_decisecs * 10;	// Unit duration
 			fac.u.inv.o.AOCcuril.currencyInfo[0].durationCurrency.durLengthTimeScale = 0;	// 1/100 s
 			fac.u.inv.o.AOCcuril.currencyInfo[0].durationCurrency.granLengthTimeUnit = call->metering_unit_period_decisecs * 10;	// Granularity
 			fac.u.inv.o.AOCcuril.currencyInfo[0].durationCurrency.granLengthTimeScale = 0;	// 1/100 s
-			fac.u.inv.o.AOCcuril.currencyInfo[1].chargedItem = 0x02;	// call setup
-			fac.u.inv.o.AOCcuril.currencyInfo[1].currencyType = 0xA2;	// FlatRate
-			strncpy((char *)fac.u.inv.o.AOCcuril.currencyInfo[1].FlatRateCurrency.currency, "EUR", 10);	// Currency value
-			fac.u.inv.o.AOCcuril.currencyInfo[1].FlatRateCurrency.currencyAmount = AOCS_CURRENCY_AMOUNT_PER_UNIT * call->metering_connect_units;
-			fac.u.inv.o.AOCcuril.currencyInfo[1].FlatRateCurrency.multiplier = 1;	// 1/100 EUR
+			fac.u.inv.o.AOCcuril.currencyInfo[1].chargedItem = 0x02;						// CallSetup
+			if(call->metering_connect_units > 1) {
+				/* Additional CallSetup charge */
+				LOGP(DISDN, LOGL_DEBUG, "AOC-S currencyInfoList: BasicComm DurationCurrency %d/100 EUR per %d/100 seconds; CallSetup FlatRate %d/100 EUR\n", AOCS_CURRENCY_AMOUNT_PER_UNIT, call->metering_unit_period_decisecs * 10, AOCS_CURRENCY_AMOUNT_PER_UNIT * (call->metering_connect_units - 1));
+				fac.u.inv.o.AOCcuril.currencyInfo[1].currencyType = 0xA2;					// FlatRate
+				strncpy((char *)fac.u.inv.o.AOCcuril.currencyInfo[1].FlatRateCurrency.currency, "EUR", 10);	// Currency value
+				fac.u.inv.o.AOCcuril.currencyInfo[1].FlatRateCurrency.currencyAmount = AOCS_CURRENCY_AMOUNT_PER_UNIT * (call->metering_connect_units - 1);
+				fac.u.inv.o.AOCcuril.currencyInfo[1].FlatRateCurrency.multiplier = 1;		// 1/100 EUR
+			}
+			else {
+				/* No additional CallSetup charge */
+				LOGP(DISDN, LOGL_DEBUG, "AOC-S currencyInfoList: BasicComm DurationCurrency %d/100 EUR per %d/100 seconds; CallSetup FreeOfCharge\n", AOCS_CURRENCY_AMOUNT_PER_UNIT, call->metering_unit_period_decisecs * 10);
+				fac.u.inv.o.AOCcuril.currencyInfo[1].currencyType = 0x84;					// Free
+			}
 		}
 
 		encodeFac(fac_ie, &fac);