diff --git a/src/libosmo-mgcp/mgcp_protocol.c b/src/libosmo-mgcp/mgcp_protocol.c
index 4fb93b0..56271e2 100644
--- a/src/libosmo-mgcp/mgcp_protocol.c
+++ b/src/libosmo-mgcp/mgcp_protocol.c
@@ -1149,7 +1149,7 @@
 	/* check connection mode setting */
 	if (conn->conn->mode != MGCP_CONN_LOOPBACK
 	    && conn->conn->mode != MGCP_CONN_RECV_ONLY
-	    && conn->end.rtp_port == 0) {
+	    && !mgcp_rtp_end_remote_addr_available(&conn->end)) {
 		LOGPCONN(conn->conn, DLMGCP, LOGL_ERROR,
 			 "MDCX: selected connection mode type requires an opposite end!\n");
 		error_code = 527;
diff --git a/tests/mgcp/mgcp_test.c b/tests/mgcp/mgcp_test.c
index 5bb7b27..6978b1d 100644
--- a/tests/mgcp/mgcp_test.c
+++ b/tests/mgcp/mgcp_test.c
@@ -128,7 +128,7 @@
 	"a=fmtp:126 0/1/2\r\n" \
 	"a=ptime:40\r\n"
 
-#define MDCX4 \
+#define MDCX4_ADDR0000 \
 	"MDCX 18983216 1@mgw MGCP 1.0\r\n" \
 	"M: sendrecv\r" \
 	"C: 2\r\n" \
@@ -143,6 +143,24 @@
 	"a=rtpmap:99 AMR/8000\r\n" \
 	"a=ptime:40\r\n"
 
+#define MDCX4_ADDR0000_RET \
+	"527 18983216 FAIL\r\n"
+
+#define MDCX4 \
+	"MDCX 18983217 1@mgw MGCP 1.0\r\n" \
+	"M: sendrecv\r" \
+	"C: 2\r\n" \
+	"I: %s\r\n" \
+	"L: p:20, a:AMR, nt:IN\r\n" \
+	"\n" \
+	"v=0\r\n" \
+	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
+	"c=IN IP4 5.6.7.8\r\n" \
+	"t=0 0\r\n" \
+	"m=audio 4441 RTP/AVP 99\r\n" \
+	"a=rtpmap:99 AMR/8000\r\n" \
+	"a=ptime:40\r\n"
+
 #define MDCX4_RET(Ident) \
 	"200 " Ident " OK\r\n" \
 	"\r\n" \
@@ -168,45 +186,45 @@
 	"a=ptime:40\r\n"
 
 #define MDCX4_PT1 \
-	"MDCX 18983217 1@mgw MGCP 1.0\r\n" \
+	"MDCX 18983218 1@mgw MGCP 1.0\r\n" \
 	"M: SENDRECV\r" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: p:20-40, a:AMR, nt:IN\r\n" \
 	"\n" \
 	"v=0\r\n" \
-	"o=- %s 23 IN IP4 0.0.0.0\r\n" \
-	"c=IN IP4 0.0.0.0\r\n" \
+	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
+	"c=IN IP4 5.6.7.8\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
 	"a=ptime:40\r\n"
 
 #define MDCX4_PT2 \
-	"MDCX 18983218 1@mgw MGCP 1.0\r\n" \
+	"MDCX 18983219 1@mgw MGCP 1.0\r\n" \
 	"M: sendrecv\r" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: p:20-20, a:AMR, nt:IN\r\n" \
 	"\n" \
 	"v=0\r\n" \
-	"o=- %s 23 IN IP4 0.0.0.0\r\n" \
-	"c=IN IP4 0.0.0.0\r\n" \
+	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
+	"c=IN IP4 5.6.7.8\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
 	"a=ptime:40\r\n"
 
 #define MDCX4_PT3 \
-	"MDCX 18983219 1@mgw MGCP 1.0\r\n" \
+	"MDCX 18983220 1@mgw MGCP 1.0\r\n" \
 	"M: sendrecv\r" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: a:AMR, nt:IN\r\n" \
 	"\n" \
 	"v=0\r\n" \
-	"o=- %s 23 IN IP4 0.0.0.0\r\n" \
-	"c=IN IP4 0.0.0.0\r\n" \
+	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
+	"c=IN IP4 5.6.7.8\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
@@ -214,47 +232,47 @@
 
 /* Test different upper/lower case in options */
 #define MDCX4_PT4 \
-	"MDCX 18983220 1@mgw MGCP 1.0\r\n" \
+	"MDCX 18983221 1@mgw MGCP 1.0\r\n" \
 	"m: sendrecv\r" \
 	"c: 2\r\n" \
 	"i: %s\r\n" \
 	"l: A:amr, NT:IN\r\n" \
 	"\n" \
 	"v=0\r\n" \
-	"o=- %s 23 IN IP4 0.0.0.0\r\n" \
-	"c=IN IP4 0.0.0.0\r\n" \
+	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
+	"c=IN IP4 5.6.7.8\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
 	"a=ptime:40\r\n"
 
 #define MDCX4_SO \
-	"MDCX 18983221 1@mgw MGCP 1.0\r\n" \
+	"MDCX 18983222 1@mgw MGCP 1.0\r\n" \
 	"M: sendonly\r" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: p:20, a:AMR, nt:IN\r\n" \
 	"\n" \
 	"v=0\r\n" \
-	"o=- %s 23 IN IP4 0.0.0.0\r\n" \
-	"c=IN IP4 0.0.0.0\r\n" \
+	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
+	"c=IN IP4 5.6.7.8\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
 	"a=ptime:40\r\n"
 
 #define MDCX4_RO \
-	"MDCX 18983222 1@mgw MGCP 1.0\r\n" \
+	"MDCX 18983223 1@mgw MGCP 1.0\r\n" \
 	"M: recvonly\r" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: p:20, a:AMR, nt:IN\r\n"
 
 #define MDCX_TOO_LONG_CI \
-	"MDCX 18983223 1@mgw MGCP 1.0\r\n" \
+	"MDCX 18983224 1@mgw MGCP 1.0\r\n" \
 	"I: 123456789012345678901234567890123\n"
 
-#define MDCX_TOO_LONG_CI_RET "510 18983223 FAIL\r\n"
+#define MDCX_TOO_LONG_CI_RET "510 18983224 FAIL\r\n"
 
 #define SHORT2	"CRCX 1"
 #define SHORT2_RET "510 000000 FAIL\r\n"
@@ -542,13 +560,14 @@
 	{"MDCX2", MDCX_UNALLOCATED, MDCX_RET},
 	{"CRCX", CRCX, CRCX_RET, 97},
 	{"MDCX3", MDCX3, MDCX3_RET, PTYPE_IGNORE},
-	{"MDCX4", MDCX4, MDCX4_RET("18983216"), 99},
-	{"MDCX4_PT1", MDCX4_PT1, MDCX4_RET("18983217"), 99},
-	{"MDCX4_PT2", MDCX4_PT2, MDCX4_RET("18983218"), 99},
-	{"MDCX4_PT3", MDCX4_PT3, MDCX4_RET("18983219"), 99},
-	{"MDCX4_PT4", MDCX4_PT4, MDCX4_RET("18983220"), 99},
-	{"MDCX4_SO", MDCX4_SO, MDCX4_RET("18983221"), 99},
-	{"MDCX4_RO", MDCX4_RO, MDCX4_RO_RET("18983222"), PTYPE_IGNORE},
+	{"MDCX4_ADDR000", MDCX4_ADDR0000, MDCX4_ADDR0000_RET},
+	{"MDCX4", MDCX4, MDCX4_RET("18983217"), 99},
+	{"MDCX4_PT1", MDCX4_PT1, MDCX4_RET("18983218"), 99},
+	{"MDCX4_PT2", MDCX4_PT2, MDCX4_RET("18983219"), 99},
+	{"MDCX4_PT3", MDCX4_PT3, MDCX4_RET("18983220"), 99},
+	{"MDCX4_PT4", MDCX4_PT4, MDCX4_RET("18983221"), 99},
+	{"MDCX4_SO", MDCX4_SO, MDCX4_RET("18983222"), 99},
+	{"MDCX4_RO", MDCX4_RO, MDCX4_RO_RET("18983223"), PTYPE_IGNORE},
 	{"DLCX", DLCX, DLCX_RET, PTYPE_IGNORE},
 	{"CRCX_ZYN", CRCX_ZYN, CRCX_ZYN_RET, 97},
 	{"EMPTY", EMPTY, EMPTY_RET},
diff --git a/tests/mgcp/mgcp_test.ok b/tests/mgcp/mgcp_test.ok
index d3f8a26..575fd83 100644
--- a/tests/mgcp/mgcp_test.ok
+++ b/tests/mgcp/mgcp_test.ok
Binary files differ