diff --git a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
index 9759303..5a024db 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
@@ -552,7 +552,8 @@
 	bsc_msg = bsc_mgcp_rewrite((char *) nat->mgcp_msg, nat->mgcp_length,
 				   sccp->bsc_endp, nat->mgcp_cfg->source_addr,
 				   mgcp_endp->bts_end.local_port, osmux_cid,
-				   &mgcp_endp->net_end.codec.payload_type);
+				   &mgcp_endp->net_end.codec.payload_type,
+				   nat->sdp_ensure_amr_mode_set);
 	if (!bsc_msg) {
 		LOGP(DMGCP, LOGL_ERROR, "Failed to patch the msg.\n");
 		return MGCP_POLICY_CONT;
@@ -746,7 +747,8 @@
 	output = bsc_mgcp_rewrite((char * ) msg->l2h, msgb_l2len(msg), -1,
 				  bsc->nat->mgcp_cfg->source_addr,
 				  endp->net_end.local_port, -1,
-				  &endp->bts_end.codec.payload_type);
+				  &endp->bts_end.codec.payload_type,
+				  bsc->nat->sdp_ensure_amr_mode_set);
 	if (!output) {
 		LOGP(DMGCP, LOGL_ERROR, "Failed to rewrite MGCP msg.\n");
 		return;
@@ -813,7 +815,7 @@
 /* we need to replace some strings... */
 struct msgb *bsc_mgcp_rewrite(char *input, int length, int endpoint,
 			      const char *ip, int port, int osmux_cid,
-			      int *payload_type)
+			      int *payload_type, int ensure_mode_set)
 {
 	static const char crcx_str[] = "CRCX ";
 	static const char dlcx_str[] = "DLCX ";
@@ -898,7 +900,7 @@
 	 * the above code made sure that we have 128 bytes lefts. So we can
 	 * safely append another line.
 	 */
-	if (!found_fmtp && payload != -1) {
+	if (ensure_mode_set && !found_fmtp && payload != -1) {
 		snprintf(buf, sizeof(buf) - 1, "a=fmtp:%d mode-set=2%s",
 			payload, cr ? "\r\n" : "\n");
 		buf[sizeof(buf) - 1] = '\0';
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat.c b/openbsc/src/osmo-bsc_nat/bsc_nat.c
index 93a9145..5c3b696 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat.c
@@ -1526,6 +1526,9 @@
 		return -5;
 	}
 
+	/* We need to add mode-set for amr codecs */
+	nat->sdp_ensure_amr_mode_set = 1;
+
 	vty_info.copyright = openbsc_copyright;
 	vty_init(&vty_info);
 	logging_vty_add_cmds(&log_info);
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c b/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c
index 2b7db2e..9e66cdc 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c
@@ -156,6 +156,8 @@
 		write_pgroup_lst(vty, pgroup);
 	if (_nat->mgcp_ipa)
 		vty_out(vty, " use-msc-ipa-for-mgcp%s", VTY_NEWLINE);
+	vty_out(vty, " %ssdp-ensure-amr-mode-set%s",
+		_nat->sdp_ensure_amr_mode_set ? "" : "no ", VTY_NEWLINE);
 
 	return CMD_SUCCESS;
 }
@@ -773,6 +775,24 @@
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_nat_sdp_amr_mode_set,
+      cfg_nat_sdp_amr_mode_set_cmd,
+      "sdp-ensure-amr-mode-set",
+      "Ensure that SDP records include a mode-set\n")
+{
+	_nat->sdp_ensure_amr_mode_set = 1;
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_nat_no_sdp_amr_mode_set,
+      cfg_nat_no_sdp_amr_mode_set_cmd,
+      "no sdp-ensure-amr-mode-set",
+      NO_STR "Ensure that SDP records include a mode-set\n")
+{
+	_nat->sdp_ensure_amr_mode_set = 0;
+	return CMD_SUCCESS;
+}
+
 /* per BSC configuration */
 DEFUN(cfg_bsc, cfg_bsc_cmd, "bsc BSC_NR",
       "BSC configuration\n" "Identifier of the BSC\n")
@@ -1274,6 +1294,9 @@
 	install_element(NAT_NODE, &cfg_nat_prefix_trie_cmd);
 	install_element(NAT_NODE, &cfg_nat_no_prefix_trie_cmd);
 
+	install_element(NAT_NODE, &cfg_nat_sdp_amr_mode_set_cmd);
+	install_element(NAT_NODE, &cfg_nat_no_sdp_amr_mode_set_cmd);
+
 	install_element(NAT_NODE, &cfg_nat_pgroup_cmd);
 	install_element(NAT_NODE, &cfg_nat_no_pgroup_cmd);
 	install_node(&pgroup_node, config_write_pgroup);