diff --git a/openbsc/src/libmgcp/mgcp_network.c b/openbsc/src/libmgcp/mgcp_network.c
index 05c3e77..219d3f9 100644
--- a/openbsc/src/libmgcp/mgcp_network.c
+++ b/openbsc/src/libmgcp/mgcp_network.c
@@ -340,7 +340,7 @@
 	return timestamp_error;
 }
 
-int mgcp_rtp_processing_default(struct mgcp_rtp_end *dst_end,
+int mgcp_rtp_processing_default(struct mgcp_endpoint *endp, struct mgcp_rtp_end *dst_end,
 				char *data, int *len, int buf_size)
 {
 	return 0;
@@ -614,12 +614,28 @@
 	if (!rtp_end->output_enabled)
 		rtp_end->dropped_packets += 1;
 	else if (is_rtp) {
-		mgcp_patch_and_count(endp, rtp_state, rtp_end, addr, buf, rc);
-		endp->cfg->rtp_processing_cb(rtp_end, buf, &rc, RTP_BUF_SIZE);
-		forward_data(rtp_end->rtp.fd, &endp->taps[tap_idx], buf, rc);
-		return mgcp_udp_send(rtp_end->rtp.fd,
-				     &rtp_end->addr,
-				     rtp_end->rtp_port, buf, rc);
+		int cont;
+		int nbytes = 0;
+		int len = rc;
+		mgcp_patch_and_count(endp, rtp_state, rtp_end, addr, buf, len);
+		do {
+			cont = endp->cfg->rtp_processing_cb(endp, rtp_end,
+							buf, &len, RTP_BUF_SIZE);
+			if (cont < 0)
+				break;
+
+			forward_data(rtp_end->rtp.fd, &endp->taps[tap_idx],
+				     buf, len);
+			rc = mgcp_udp_send(rtp_end->rtp.fd,
+					   &rtp_end->addr,
+					   rtp_end->rtp_port, buf, len);
+
+			if (rc <= 0)
+				return rc;
+			nbytes += rc;
+			len = cont;
+		} while (len > 0);
+		return nbytes;
 	} else if (!tcfg->omit_rtcp) {
 		return mgcp_udp_send(rtp_end->rtcp.fd,
 				     &rtp_end->addr,
diff --git a/openbsc/src/libmgcp/mgcp_protocol.c b/openbsc/src/libmgcp/mgcp_protocol.c
index 6e974f1..21b9ff0 100644
--- a/openbsc/src/libmgcp/mgcp_protocol.c
+++ b/openbsc/src/libmgcp/mgcp_protocol.c
@@ -621,6 +621,15 @@
 	rtp->channels = channels;
 	rtp->subtype_name = talloc_strdup(ctx, audio_codec);
 	rtp->audio_name = talloc_strdup(ctx, audio_name);
+
+	if (!strcmp(audio_codec, "G729")) {
+		rtp->frame_duration_num = 10;
+		rtp->frame_duration_den = 1000;
+	} else {
+		rtp->frame_duration_num = DEFAULT_RTP_AUDIO_FRAME_DUR_NUM;
+		rtp->frame_duration_den = DEFAULT_RTP_AUDIO_FRAME_DUR_DEN;
+	}
+
 	if (channels != 1)
 		LOGP(DMGCP, LOGL_NOTICE,
 		     "Channels != 1 in SDP: '%s'\n", audio_name);
@@ -944,11 +953,16 @@
 	set_audio_info(p->cfg, &endp->bts_end, tcfg->audio_payload, tcfg->audio_name);
 	endp->bts_end.fmtp_extra = talloc_strdup(tcfg->endpoints,
 						tcfg->audio_fmtp_extra);
-	if (have_sdp) {
+	if (have_sdp)
 		parse_sdp_data(&endp->net_end, p);
-		setup_rtp_processing(endp);
+
+	if (p->cfg->bts_force_ptime) {
+		endp->bts_end.packet_duration_ms = p->cfg->bts_force_ptime;
+		endp->bts_end.force_output_ptime = 1;
 	}
 
+	setup_rtp_processing(endp);
+
 	/* policy CB */
 	if (p->cfg->policy_cb) {
 		int rc;
diff --git a/openbsc/src/libmgcp/mgcp_vty.c b/openbsc/src/libmgcp/mgcp_vty.c
index 1f8a63a..26b5706 100644
--- a/openbsc/src/libmgcp/mgcp_vty.c
+++ b/openbsc/src/libmgcp/mgcp_vty.c
@@ -366,6 +366,26 @@
       RTP_STR
       "Apply IP_TOS to the audio stream\n" "The DSCP value\n")
 
+#define FORCE_PTIME_STR "Force a fixed ptime for packets sent to the BTS"
+DEFUN(cfg_mgcp_rtp_force_ptime,
+      cfg_mgcp_rtp_force_ptime_cmd,
+      "rtp force-ptime (10|20|40)",
+      RTP_STR FORCE_PTIME_STR
+      "The required ptime (packet duration) in ms\n")
+{
+	g_cfg->bts_force_ptime = atoi(argv[0]);
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_mgcp_no_rtp_force_ptime,
+      cfg_mgcp_no_rtp_force_ptime_cmd,
+      "no rtp force-ptime",
+      NO_STR RTP_STR FORCE_PTIME_STR)
+{
+	g_cfg->bts_force_ptime = 0;
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_mgcp_sdp_fmtp_extra,
       cfg_mgcp_sdp_fmtp_extra_cmd,
       "sdp audio fmtp-extra .NAME",
@@ -1123,6 +1143,8 @@
 	install_element(MGCP_NODE, &cfg_mgcp_rtp_transcoder_base_cmd);
 	install_element(MGCP_NODE, &cfg_mgcp_rtp_ip_dscp_cmd);
 	install_element(MGCP_NODE, &cfg_mgcp_rtp_ip_tos_cmd);
+	install_element(MGCP_NODE, &cfg_mgcp_rtp_force_ptime_cmd);
+	install_element(MGCP_NODE, &cfg_mgcp_no_rtp_force_ptime_cmd);
 	install_element(MGCP_NODE, &cfg_mgcp_rtp_keepalive_cmd);
 	install_element(MGCP_NODE, &cfg_mgcp_rtp_keepalive_once_cmd);
 	install_element(MGCP_NODE, &cfg_mgcp_no_rtp_keepalive_cmd);