diff --git a/tests/msc_vlr/msc_vlr_test_call.c b/tests/msc_vlr/msc_vlr_test_call.c
index a547935..06602f7 100644
--- a/tests/msc_vlr/msc_vlr_test_call.c
+++ b/tests/msc_vlr/msc_vlr_test_call.c
@@ -227,7 +227,7 @@
 
 	btw("Assignment succeeds, triggering CRCX to CN");
 	expect_crcx(RTP_TO_CN);
-	ms_sends_assignment_complete(CODEC_AMR_8000_1);
+	ms_sends_assignment_complete("AMR");
 	OSMO_ASSERT(got_crcx);
 
 	btw("CN RTP address is available, trigger MNCC_RTP_CREATE");
@@ -339,7 +339,7 @@
 
 	btw("Assignment completes, triggering CRCX to CN");
 	expect_crcx(RTP_TO_CN);
-	ms_sends_assignment_complete(CODEC_AMR_8000_1);
+	ms_sends_assignment_complete("AMR");
 	OSMO_ASSERT(got_crcx);
 
 	btw("When the CN side RTP address is known, send MNCC_RTP_CREATE");
@@ -442,7 +442,7 @@
 
 	btw("Assignment completes, triggering CRCX to CN");
 	expect_crcx(RTP_TO_CN);
-	ms_sends_assignment_complete(CODEC_AMR_8000_1);
+	ms_sends_assignment_complete("AMR");
 	OSMO_ASSERT(got_crcx);
 
 	btw("When the CN side RTP address is known, send MNCC_RTP_CREATE");
@@ -539,7 +539,7 @@
 
 	btw("Assignment succeeds, triggering CRCX to CN");
 	expect_crcx(RTP_TO_CN);
-	ms_sends_assignment_complete(CODEC_AMR_8000_1);
+	ms_sends_assignment_complete("AMR");
 	OSMO_ASSERT(got_crcx);
 
 	btw("CN RTP address is available, trigger MNCC_RTP_CREATE");
@@ -635,7 +635,7 @@
 
 	btw("Assignment succeeds, triggering CRCX to CN");
 	expect_crcx(RTP_TO_CN);
-	ms_sends_assignment_complete(CODEC_AMR_8000_1);
+	ms_sends_assignment_complete("AMR");
 	OSMO_ASSERT(got_crcx);
 
 	btw("CN RTP address is available, trigger MNCC_RTP_CREATE");
diff --git a/tests/msc_vlr/msc_vlr_test_call.err b/tests/msc_vlr/msc_vlr_test_call.err
index 877015a..d97806d 100644
--- a/tests/msc_vlr/msc_vlr_test_call.err
+++ b/tests/msc_vlr/msc_vlr_test_call.err
@@ -314,13 +314,12 @@
 DMSC dummy_msc_i(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){0}: Received Event MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST
 - Assignment succeeds, triggering CRCX to CN
 DIUCS msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){MSC_A_ST_COMMUNICATING}: RAN decode: ASSIGNMENT_COMPLETE
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483649:RTP_TO_RAN:no-CI){UNINITIALIZED}: setting codecs to AMR:octet-align=1#112
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483649:RTP_TO_RAN:no-CI:local-10-23-23-1-23){UNINITIALIZED}: setting remote addr to 1.2.3.4:1234
+DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483649:RTP_TO_RAN:no-CI){UNINITIALIZED}: setting remote addr to 1.2.3.4:1234
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483649:RTP_TO_RAN:no-CI:local-10-23-23-1-23:remote-1-2-3-4-1234){UNINITIALIZED}: Not committing: no MGW endpoint CI set up
-  MGW <--CRCX to RTP_TO_CN-- MSC: callref=0x80000001 codecs=AMR:octet-align=1#112
+  MGW <--CRCX to RTP_TO_CN-- MSC: callref=0x80000001 codecs=VND.3GPP.IUFP/16000#96
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){UNINITIALIZED}: Allocated
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){UNINITIALIZED}: is child of call_leg(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ)
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483649:RTP_TO_CN:no-CI){UNINITIALIZED}: setting codecs to AMR:octet-align=1#112
+DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483649:RTP_TO_CN:no-CI){UNINITIALIZED}: setting codecs to VND.3GPP.IUFP/16000#96
 - CN RTP address is available, trigger MNCC_RTP_CREATE
   MGW --CRCX OK to RTP_TO_CN--> MSC
 DCC call_leg(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){ESTABLISHING}: Received Event CALL_LEG_EV_RTP_STREAM_ADDR_AVAILABLE
@@ -800,13 +799,12 @@
 DMSC dummy_msc_i(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){0}: Received Event MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST
 - Assignment completes, triggering CRCX to CN
 DIUCS msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){MSC_A_ST_COMMUNICATING}: RAN decode: ASSIGNMENT_COMPLETE
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_RAN:no-CI){UNINITIALIZED}: setting codecs to AMR:octet-align=1#112
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_RAN:no-CI:local-10-23-23-1-23){UNINITIALIZED}: setting remote addr to 1.2.3.4:1234
+DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_RAN:no-CI){UNINITIALIZED}: setting remote addr to 1.2.3.4:1234
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_RAN:no-CI:local-10-23-23-1-23:remote-1-2-3-4-1234){UNINITIALIZED}: Not committing: no MGW endpoint CI set up
-  MGW <--CRCX to RTP_TO_CN-- MSC: callref=0x423 codecs=AMR:octet-align=1#112
+  MGW <--CRCX to RTP_TO_CN-- MSC: callref=0x423 codecs=VND.3GPP.IUFP/16000#96
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){UNINITIALIZED}: Allocated
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){UNINITIALIZED}: is child of call_leg(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP)
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_CN:no-CI){UNINITIALIZED}: setting codecs to AMR:octet-align=1#112
+DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_CN:no-CI){UNINITIALIZED}: setting codecs to VND.3GPP.IUFP/16000#96
 - When the CN side RTP address is known, send MNCC_RTP_CREATE
   MGW --CRCX OK to RTP_TO_CN--> MSC
 DCC call_leg(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){ESTABLISHING}: Received Event CALL_LEG_EV_RTP_STREAM_ADDR_AVAILABLE
@@ -1270,13 +1268,12 @@
 DMSC dummy_msc_i(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){0}: Received Event MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST
 - Assignment completes, triggering CRCX to CN
 DIUCS msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){MSC_A_ST_COMMUNICATING}: RAN decode: ASSIGNMENT_COMPLETE
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_RAN:no-CI){UNINITIALIZED}: setting codecs to AMR:octet-align=1#112
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_RAN:no-CI:local-10-23-23-1-23){UNINITIALIZED}: setting remote addr to 1.2.3.4:1234
+DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_RAN:no-CI){UNINITIALIZED}: setting remote addr to 1.2.3.4:1234
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_RAN:no-CI:local-10-23-23-1-23:remote-1-2-3-4-1234){UNINITIALIZED}: Not committing: no MGW endpoint CI set up
-  MGW <--CRCX to RTP_TO_CN-- MSC: callref=0x423 codecs=AMR:octet-align=1#112
+  MGW <--CRCX to RTP_TO_CN-- MSC: callref=0x423 codecs=VND.3GPP.IUFP/16000#96
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){UNINITIALIZED}: Allocated
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){UNINITIALIZED}: is child of call_leg(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP)
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_CN:no-CI){UNINITIALIZED}: setting codecs to AMR:octet-align=1#112
+DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP:trans-0:call-1059:RTP_TO_CN:no-CI){UNINITIALIZED}: setting codecs to VND.3GPP.IUFP/16000#96
 - When the CN side RTP address is known, send MNCC_RTP_CREATE
   MGW --CRCX OK to RTP_TO_CN--> MSC
 DCC call_leg(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){ESTABLISHING}: Received Event CALL_LEG_EV_RTP_STREAM_ADDR_AVAILABLE
@@ -1680,13 +1677,12 @@
 DMSC dummy_msc_i(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){0}: Received Event MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST
 - Assignment succeeds, triggering CRCX to CN
 DIUCS msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){MSC_A_ST_COMMUNICATING}: RAN decode: ASSIGNMENT_COMPLETE
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483650:RTP_TO_RAN:no-CI){UNINITIALIZED}: setting codecs to AMR:octet-align=1#112
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483650:RTP_TO_RAN:no-CI:local-10-23-23-1-23){UNINITIALIZED}: setting remote addr to 1.2.3.4:1234
+DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483650:RTP_TO_RAN:no-CI){UNINITIALIZED}: setting remote addr to 1.2.3.4:1234
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483650:RTP_TO_RAN:no-CI:local-10-23-23-1-23:remote-1-2-3-4-1234){UNINITIALIZED}: Not committing: no MGW endpoint CI set up
-  MGW <--CRCX to RTP_TO_CN-- MSC: callref=0x80000002 codecs=AMR:octet-align=1#112
+  MGW <--CRCX to RTP_TO_CN-- MSC: callref=0x80000002 codecs=VND.3GPP.IUFP/16000#96
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){UNINITIALIZED}: Allocated
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){UNINITIALIZED}: is child of call_leg(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ)
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483650:RTP_TO_CN:no-CI){UNINITIALIZED}: setting codecs to AMR:octet-align=1#112
+DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483650:RTP_TO_CN:no-CI){UNINITIALIZED}: setting codecs to VND.3GPP.IUFP/16000#96
 - CN RTP address is available, trigger MNCC_RTP_CREATE
   MGW --CRCX OK to RTP_TO_CN--> MSC
 DCC call_leg(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){ESTABLISHING}: Received Event CALL_LEG_EV_RTP_STREAM_ADDR_AVAILABLE
@@ -2107,13 +2103,12 @@
 DMSC dummy_msc_i(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){0}: Received Event MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST
 - Assignment succeeds, triggering CRCX to CN
 DIUCS msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){MSC_A_ST_COMMUNICATING}: RAN decode: ASSIGNMENT_COMPLETE
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483651:RTP_TO_RAN:no-CI){UNINITIALIZED}: setting codecs to AMR:octet-align=1#112
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483651:RTP_TO_RAN:no-CI:local-10-23-23-1-23){UNINITIALIZED}: setting remote addr to 1.2.3.4:1234
+DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483651:RTP_TO_RAN:no-CI){UNINITIALIZED}: setting remote addr to 1.2.3.4:1234
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483651:RTP_TO_RAN:no-CI:local-10-23-23-1-23:remote-1-2-3-4-1234){UNINITIALIZED}: Not committing: no MGW endpoint CI set up
-  MGW <--CRCX to RTP_TO_CN-- MSC: callref=0x80000003 codecs=AMR:octet-align=1#112
+  MGW <--CRCX to RTP_TO_CN-- MSC: callref=0x80000003 codecs=VND.3GPP.IUFP/16000#96
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){UNINITIALIZED}: Allocated
 DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){UNINITIALIZED}: is child of call_leg(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ)
-DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483651:RTP_TO_CN:no-CI){UNINITIALIZED}: setting codecs to AMR:octet-align=1#112
+DCC rtp_stream(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ:trans-8:call-2147483651:RTP_TO_CN:no-CI){UNINITIALIZED}: setting codecs to VND.3GPP.IUFP/16000#96
 - CN RTP address is available, trigger MNCC_RTP_CREATE
   MGW --CRCX OK to RTP_TO_CN--> MSC
 DCC call_leg(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:CM_SERVICE_REQ){ESTABLISHING}: Received Event CALL_LEG_EV_RTP_STREAM_ADDR_AVAILABLE
diff --git a/tests/msc_vlr/msc_vlr_tests.c b/tests/msc_vlr/msc_vlr_tests.c
index 45b97a2..646633c 100644
--- a/tests/msc_vlr/msc_vlr_tests.c
+++ b/tests/msc_vlr/msc_vlr_tests.c
@@ -1014,15 +1014,19 @@
 		g_msub = NULL;
 }
 
-void ms_sends_assignment_complete(enum mgcp_codecs assigned_codec)
+void ms_sends_assignment_complete(const char *sdp_codec_name)
 {
 	struct ran_msg ran_dec;
+	const struct codec_mapping *m = codec_mapping_by_subtype_name(sdp_codec_name);
+	OSMO_ASSERT(m);
+	OSMO_ASSERT(m->has_gsm0808_speech_codec);
 
 	ran_dec = (struct ran_msg){
 		.msg_type = RAN_MSG_ASSIGNMENT_COMPLETE,
 		.assignment_complete = {
 			.codec_present = true,
-			.codec = assigned_codec,
+			.codec = m->gsm0808_speech_codec,
+			.codec_with_iuup = (rx_from_ran == OSMO_RAT_UTRAN_IU),
 		},
 	};
 	osmo_sockaddr_str_from_str(&ran_dec.assignment_complete.remote_rtp, "1.2.3.4", 1234);
diff --git a/tests/msc_vlr/msc_vlr_tests.h b/tests/msc_vlr/msc_vlr_tests.h
index 1f83013..1a57101 100644
--- a/tests/msc_vlr/msc_vlr_tests.h
+++ b/tests/msc_vlr/msc_vlr_tests.h
@@ -186,7 +186,7 @@
 void ms_sends_classmark_update(const struct osmo_gsm48_classmark *classmark);
 void ms_sends_ciphering_mode_complete(const char *inner_nas_msg);
 void ms_sends_security_mode_complete(uint8_t utran_encryption);
-void ms_sends_assignment_complete(enum mgcp_codecs assigned_codec);
+void ms_sends_assignment_complete(const char *sdp_codec_name);
 void gsup_rx(const char *rx_hex, const char *expect_tx_hex);
 void send_sms(struct vlr_subscr *receiver,
 	      struct vlr_subscr *sender,