diff --git a/library/MGCP_Templates.ttcn b/library/MGCP_Templates.ttcn
index 506100f..4cc2c6b 100644
--- a/library/MGCP_Templates.ttcn
+++ b/library/MGCP_Templates.ttcn
@@ -49,6 +49,12 @@
 		val := hex2str(cid)
 	};
 
+	/* Osmocom extension: X-Osmux: {*,%u} */
+	template MgcpParameter ts_MgcpParOsmuxCID(MgcpOsmuxCID osmux_cid) := {
+		code := "X-OSMUX",
+		val := f_mgcp_osmux_cid_encode(osmux_cid)
+	};
+
 	/* osmo-bsc_mgcp implements L/C/M/X only, osmo-mgw adds 'I' */
 	/* SDP: osmo-bsc_mgcp implements Tx of v,o,s,c,t,m,a */
 
@@ -89,6 +95,18 @@
 		sdp := sdp
 	}
 
+	template MgcpCommand ts_CRCX_osmux(MgcpTransId trans_id, charstring ep, MgcpConnectionMode mode, MgcpCallId call_id, MgcpOsmuxCID osmux_cid, template SDP_Message sdp := omit) := {
+		line := t_MgcpCmdLine("CRCX", trans_id, ep),
+		params := {
+			t_MgcpParConnMode(mode),
+			ts_MgcpParCallId(call_id),
+			//t_MgcpParReqId(omit),
+			t_MgcpParLocConnOpt("p:20, a:AMR"),
+			ts_MgcpParOsmuxCID(osmux_cid)
+		},
+		sdp := sdp
+	}
+
 	template MgcpCommand tr_CRCX(template MgcpEndpoint ep := ?) := {
 		line := t_MgcpCmdLine("CRCX", ?, ep),
 		params := *,
@@ -105,6 +123,16 @@
 		sdp := ?
 	}
 
+	template MgcpResponse tr_CRCX_ACK_osmux := {
+		line := {
+			code := "200",
+			trans_id := ?,
+			string := "OK"
+		},
+		params:= { { "I", ? }, {"X-OSMUX", ?}, *},
+		sdp := ?
+	}
+
 	template MgcpResponse ts_CRCX_ACK(MgcpTransId trans_id, MgcpConnectionId conn_id, template SDP_Message sdp := omit) := {
 		line := {
 			code := "200",
@@ -127,6 +155,19 @@
 		sdp := sdp
 	}
 
+	template MgcpCommand ts_MDCX_osmux(MgcpTransId trans_id, charstring ep, MgcpConnectionMode mode, MgcpCallId call_id, MgcpConnectionId conn_id, MgcpOsmuxCID osmux_cid, template SDP_Message sdp := omit) := {
+		line := t_MgcpCmdLine("MDCX", trans_id, ep),
+		params := {
+			t_MgcpParConnMode(mode),
+			ts_MgcpParCallId(call_id),
+			ts_MgcpParConnectionId(conn_id),
+			//t_MgcpParReqId(omit),
+			t_MgcpParLocConnOpt("p:20, a:AMR"),
+			ts_MgcpParOsmuxCID(osmux_cid)
+		},
+		sdp := sdp
+	}
+
 	template MgcpCommand tr_MDCX := {
 		line := t_MgcpCmdLine("MDCX", ?, ?),
 		params := *,
@@ -286,6 +327,21 @@
 		}
 	}
 
+	/* -1 is wildcard, positive is translated as string */
+	function f_mgcp_osmux_cid_encode(MgcpOsmuxCID osmux_cid) return charstring {
+		if (osmux_cid == -1) {
+			return "*";
+		}
+		return int2str(osmux_cid);
+	}
+
+	function f_mgcp_osmux_cid_decode(charstring osmux_cid) return MgcpOsmuxCID {
+		if (osmux_cid == "*") {
+			return -1;
+		}
+		return str2int(osmux_cid);
+	}
+
 	function f_mgcp_contains_par(MgcpMessage msg, MgcpInfoCode code) return boolean {
 		var MgcpParameterList pars;
 		if (ischosen(msg.command)) {
@@ -352,6 +408,10 @@
 		return str2hex(f_MgcpCmd_extract_par(cmd, "I"));
 	}
 
+	function f_MgcpCmd_extract_osmux_cid(MgcpCommand cmd) return MgcpOsmuxCID {
+		return f_mgcp_osmux_cid_decode(f_MgcpCmd_extract_par(cmd, "X-OSMUX"));
+	}
+
 
 	function f_mgcp_alloc_tid() return MgcpTransId {
 		return int2str(float2int(rnd()*2147483647.0));
diff --git a/library/MGCP_Types.ttcn b/library/MGCP_Types.ttcn
index 8e11c7a..b56734c 100644
--- a/library/MGCP_Types.ttcn
+++ b/library/MGCP_Types.ttcn
@@ -24,13 +24,14 @@
 	type hexstring MgcpCallId	length(1..32);	/* 3.2.2.2 */
 	type hexstring MgcpConnectionId	length(1..32);	/* 3.2.2.5 */
 	type hexstring MgcpRequestId	length(1..32);	/* 3.2.2.18 */
+	type integer MgcpOsmuxCID	(-1 .. 255);
 	type charstring MgcpResponseCode (pattern "\d#(3)");
 
 	type charstring MgcpInfoCode ("B", "C", "I", "N", "X", "L", "M", "R",
 				      "S", "D", "O", "P", "E", "Z", "Q", "T",
 				      "RC", "LC", "A", "ES", "RM", "RD", "PL",
-				      "MD", "X-Osmo-CP") with {
-		variant "TEXT_CODING(,convert=upper_case,'([BCINXLMRSDOPEZQTA])|(RC)|(LC)|(ES)|(RM)|(RD)|(PL)|(MD)|(X-Osmo-CP)',case_insensitive)"
+				      "MD", "X-OSMO-CP", "X-OSMUX") with {
+		variant "TEXT_CODING(,convert=upper_case,'([BCINXLMRSDOPEZQTA])|(RC)|(LC)|(ES)|(RM)|(RD)|(PL)|(MD)|(X-OSMO-CP)|(X-OSMUX)',case_insensitive)"
 	};
 
 	/* 3.2.2.6 */
diff --git a/library/OSMUX_CodecPort.ttcn b/library/OSMUX_CodecPort.ttcn
new file mode 100644
index 0000000..ce83ab4
--- /dev/null
+++ b/library/OSMUX_CodecPort.ttcn
@@ -0,0 +1,74 @@
+module OSMUX_CodecPort {
+
+/* Simple Osmux Codec Port, translating between raw UDP primitives with
+ * octetstring payload towards the IPL4asp provider, and Osmux primitives
+ * which carry the decoded abstract Osmux data types as payload.
+ *
+ * (C) 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * All rights reserved.
+ *
+ * Author: Pau Espin Pedrol <pespin@sysmocom.de>
+ *
+ * Released under the terms of GNU General Public License, Version 2 or
+ * (at your option) any later version.
+ */
+
+	import from IPL4asp_PortType all;
+	import from IPL4asp_Types all;
+	import from OSMUX_Types all;
+
+	type record Osmux_RecvFrom {
+		ConnectionId		connId,
+		HostName		remName,
+		PortNumber		remPort,
+		HostName		locName,
+		PortNumber		locPort,
+		OSMUX_PDU	msg
+	};
+
+	template Osmux_RecvFrom t_Osmux_RecvFrom(template OSMUX_PDU msg) := {
+		connId := ?,
+		remName := ?,
+		remPort := ?,
+		locName := ?,
+		locPort := ?,
+		msg := msg
+	}
+
+	type record Osmux_Send {
+		ConnectionId		connId,
+		OSMUX_PDU	msg
+	}
+
+	template Osmux_Send t_Osmux_Send(template ConnectionId connId, template OSMUX_PDU msg) := {
+		connId := connId,
+		msg := msg
+	}
+
+	private function IPL4_to_Osmux_RecvFrom(in ASP_RecvFrom pin, out Osmux_RecvFrom pout) {
+		pout.connId := pin.connId;
+		pout.remName := pin.remName;
+		pout.remPort := pin.remPort;
+		pout.locName := pin.locName;
+		pout.locPort := pin.locPort;
+		pout.msg := dec_OSMUX_PDU(pin.msg)
+	} with { extension "prototype(fast)" };
+
+	private function Osmux_to_IPL4_Send(in Osmux_Send pin, out ASP_Send pout) {
+		pout.connId := pin.connId;
+		pout.proto := { udp := {} };
+		pout.msg := enc_OSMUX_PDU(pin.msg);
+	} with { extension "prototype(fast)" };
+
+	type port OSMUX_CODEC_PT message {
+		out	Osmux_Send;
+		in	Osmux_RecvFrom,
+			ASP_ConnId_ReadyToRelease,
+			ASP_Event;
+	} with { extension "user IPL4asp_PT
+		out(Osmux_Send -> ASP_Send:function(Osmux_to_IPL4_Send))
+		in(ASP_RecvFrom -> Osmux_RecvFrom: function(IPL4_to_Osmux_RecvFrom);
+		   ASP_ConnId_ReadyToRelease -> ASP_ConnId_ReadyToRelease: simple;
+		   ASP_Event -> ASP_Event: simple)"
+	}
+}
diff --git a/library/OSMUX_CodecPort_CtrlFunct.ttcn b/library/OSMUX_CodecPort_CtrlFunct.ttcn
new file mode 100644
index 0000000..aabb86f
--- /dev/null
+++ b/library/OSMUX_CodecPort_CtrlFunct.ttcn
@@ -0,0 +1,44 @@
+module OSMUX_CodecPort_CtrlFunct {
+
+  import from OSMUX_CodecPort all;
+  import from IPL4asp_Types all;
+
+  external function f_IPL4_listen(
+    inout OSMUX_CODEC_PT portRef,
+    in HostName locName,
+    in PortNumber locPort,
+    in ProtoTuple proto,
+    in OptionList options := {}
+  ) return Result;
+
+  external function f_IPL4_connect(
+    inout OSMUX_CODEC_PT portRef,
+    in HostName remName,
+    in PortNumber remPort,
+    in HostName locName,
+    in PortNumber locPort,
+    in ConnectionId connId,
+    in ProtoTuple proto,
+    in OptionList options := {}
+  ) return Result;
+
+  external function f_IPL4_close(
+    inout OSMUX_CODEC_PT portRef,
+    in ConnectionId id,
+    in ProtoTuple proto := { unspecified := {} }
+  ) return Result;
+
+  external function f_IPL4_setUserData(
+    inout OSMUX_CODEC_PT portRef,
+    in ConnectionId id,
+    in UserData userData
+  ) return Result;
+
+  external function f_IPL4_getUserData(
+    inout OSMUX_CODEC_PT portRef,
+    in ConnectionId id,
+    out UserData userData
+  ) return Result;
+
+}
+
diff --git a/library/OSMUX_CodecPort_CtrlFunctDef.cc b/library/OSMUX_CodecPort_CtrlFunctDef.cc
new file mode 100644
index 0000000..b877f2d
--- /dev/null
+++ b/library/OSMUX_CodecPort_CtrlFunctDef.cc
@@ -0,0 +1,55 @@
+#include "IPL4asp_PortType.hh"
+#include "OSMUX_CodecPort.hh"
+#include "IPL4asp_PT.hh"
+
+namespace OSMUX__CodecPort__CtrlFunct {
+
+  IPL4asp__Types::Result f__IPL4__listen(
+    OSMUX__CodecPort::OSMUX__CODEC__PT& portRef,
+    const IPL4asp__Types::HostName& locName,
+    const IPL4asp__Types::PortNumber& locPort,
+    const IPL4asp__Types::ProtoTuple& proto,
+    const IPL4asp__Types::OptionList& options)
+  {
+    return f__IPL4__PROVIDER__listen(portRef, locName, locPort, proto, options);
+  }
+
+  IPL4asp__Types::Result f__IPL4__connect(
+    OSMUX__CodecPort::OSMUX__CODEC__PT& portRef,
+    const IPL4asp__Types::HostName& remName,
+    const IPL4asp__Types::PortNumber& remPort,
+    const IPL4asp__Types::HostName& locName,
+    const IPL4asp__Types::PortNumber& locPort,
+    const IPL4asp__Types::ConnectionId& connId,
+    const IPL4asp__Types::ProtoTuple& proto,
+    const IPL4asp__Types::OptionList& options)
+  {
+    return f__IPL4__PROVIDER__connect(portRef, remName, remPort,
+                                      locName, locPort, connId, proto, options);
+  }
+
+  IPL4asp__Types::Result f__IPL4__close(
+    OSMUX__CodecPort::OSMUX__CODEC__PT& portRef,
+    const IPL4asp__Types::ConnectionId& connId,
+    const IPL4asp__Types::ProtoTuple& proto)
+  {
+      return f__IPL4__PROVIDER__close(portRef, connId, proto);
+  }
+
+  IPL4asp__Types::Result f__IPL4__setUserData(
+    OSMUX__CodecPort::OSMUX__CODEC__PT& portRef,
+    const IPL4asp__Types::ConnectionId& connId,
+    const IPL4asp__Types::UserData& userData)
+  {
+    return f__IPL4__PROVIDER__setUserData(portRef, connId, userData);
+  }
+
+  IPL4asp__Types::Result f__IPL4__getUserData(
+    OSMUX__CodecPort::OSMUX__CODEC__PT& portRef,
+    const IPL4asp__Types::ConnectionId& connId,
+    IPL4asp__Types::UserData& userData)
+  {
+    return f__IPL4__PROVIDER__getUserData(portRef, connId, userData);
+  }
+
+}
diff --git a/library/OSMUX_Emulation.ttcn b/library/OSMUX_Emulation.ttcn
new file mode 100644
index 0000000..e1275b9
--- /dev/null
+++ b/library/OSMUX_Emulation.ttcn
@@ -0,0 +1,575 @@
+module OSMUX_Emulation {
+
+/* Functionalities that we want this module to implement:
+ *  * act as a Osmux source that generates a Osmux Stream
+ *  * act as a Osmux sink that consumes a Osmux Stream
+ *
+ * for all of the above, we want to be able to
+ *  * specify the payload type
+ *  * specify the interval / sample rate
+ *  * create drop-outs in the stream
+ *  * detect reordered or lost frames
+ *  * validate if the size of the frames matches epectations
+ *  * play back real audio (at least some tones?)
+ *  * enable/disable generation/verification of RTCP
+ */
+
+/* Ideas:
+
+* each component consists of transmitter and receiver
+* transmitters and receivers can be operated as tuple?
+* high-level operation
+** set-up config at transmitter + receiver
+** transmit sequence of payloads
+** verify receiption of those payloads
+* can operate full-duplex/bi-directional as needed
+
+* transmitter
+** trigger transmission of n number of packets
+** transmit them at normal ptime interval
+** payload size configurable
+** payload contents PRBS or the like
+
+* receiver
+** count number of related packets at receiver
+** check received payload type
+** check received timestamp increments
+** check received seq_nr increments
+** (optionally) check for SSRC
+** (optionally) check for payload size
+** (optionally) check for payload contents
+
+* later
+** how to test transcoding?
+** how to test pure play-out endpoints (rx only)?
+** how to test "Rx from wrong IP/port" scenarios?
+** how to test RTCP?
+** maybe keep ports un-connected to show wrong src -lrt
+
+*/
+
+
+
+
+import from General_Types all;
+import from Osmocom_Types all;
+import from IPL4asp_Types all;
+import from OSMUX_Types all;
+import from OSMUX_CodecPort all;
+import from OSMUX_CodecPort_CtrlFunct all;
+
+type component OSMUX_Emulation_CT {
+	/* down-facing ports for Osmux on top of IPL4asp */
+	port OSMUX_CODEC_PT OSMUX;
+	var integer g_osmux_conn_id := -1;
+
+	/* user-facing port for controlling the binding */
+	port OsmuxEM_CTRL_PT CTRL;
+
+	/* configurable by user, should be fixed */
+	var OsmuxemConfig g_cfg := c_OsmuxemDefaultCfg;
+
+	/* statistics */
+	var OsmuxemStats g_stat := c_OsmuxemStatsReset;
+
+	var HostName g_remote_host;
+	var PortNumber g_remote_port;
+	var HostName g_local_host;
+	var PortNumber g_local_port;
+
+	/* state variables, change over time */
+	var boolean g_rx_enabled := false;
+	var boolean g_tx_connected := false; /* Set to true after connect() */
+
+	var INT7b g_rx_payload_type := 0;
+	var LIN2_BO_LAST g_rx_last_seq;
+	var uint32_t g_rx_last_ts;
+
+	var RxHandleTableRec RxHandleTable[16];
+	var OsmuxTxHandle TxHandleList[16];
+}
+
+type record RxHandleTableRec {
+	OsmuxCID cid,
+	OsmuxRxHandle vc_conn
+};
+
+type record OsmuxRxHandle {
+	OsmuxCID cid,
+	boolean first_seq_seen,
+	INT1 last_seq_ack
+};
+
+const OsmuxRxHandle c_OsmuxemDefaultRxHandle := {
+	cid := 0,
+	first_seq_seen := false,
+	last_seq_ack := 0
+}
+
+type record OsmuxTxHandle {
+	INT2b ft,
+	BIT1 amr_f,
+	BIT1 amr_q,
+	INT1 seq,
+	OsmuxCID cid,
+	INT4b amr_ft,
+	INT4b amr_cmr
+};
+
+template OsmuxTxHandle t_TxHandleAMR590(OsmuxCID cid) := {
+	ft := 1,//enum2int(OsmuxFT:OSMUX_FT_AMR)
+	amr_f := '0'B, /* this frame is the last frame in this payload */
+	amr_q := '1'B, /* frame not damaged */
+	seq := 12,
+	cid := cid,
+	amr_ft := 2, /* AMR 5.90 */
+	amr_cmr := 0
+};
+
+type enumerated OsmuxemMode {
+	OSMUXEM_MODE_NONE,
+	OSMUXEM_MODE_TXONLY,
+	OSMUXEM_MODE_RXONLY,
+	OSMUXEM_MODE_BIDIR
+};
+
+type record OsmuxemStats {
+	/* number of packets transmitted */
+	integer num_pkts_tx,
+	/* number of Osmux payload bytes transmitted */
+	integer bytes_payload_tx,
+
+	/* number of packets received */
+	integer num_pkts_rx,
+	/* number of Osmux payload bytes received */
+	integer bytes_payload_rx,
+	/* number of packets received out-of-sequence */
+	integer num_pkts_rx_err_seq,
+	/* number of packets received during Rx disable */
+	integer num_pkts_rx_err_disabled,
+	/* number of packets received with mismatching payload */
+	integer num_pkts_rx_err_payload
+}
+
+const OsmuxemStats c_OsmuxemStatsReset := {
+	num_pkts_tx := 0,
+	bytes_payload_tx := 0,
+	num_pkts_rx := 0,
+	bytes_payload_rx := 0,
+	num_pkts_rx_err_seq := 0,
+	num_pkts_rx_err_disabled := 0,
+	num_pkts_rx_err_payload := 0
+}
+
+type record OsmuxemConfig {
+	INT3b batch_size,
+	integer tx_duration_ms,
+	octetstring tx_fixed_payload optional,
+	octetstring rx_fixed_payload optional
+};
+
+const OsmuxemConfig c_OsmuxemDefaultCfg := {
+	batch_size := 4,
+	tx_duration_ms := 20 * 4, /* 4 is batch_size */
+	tx_fixed_payload := '010203040102030401020304010203040102030401020304'O,
+	rx_fixed_payload := '010203040102030401020304010203040102030401020304'O
+}
+
+signature OsmuxEM_bind(in HostName local_host, inout PortNumber local_port);
+signature OsmuxEM_connect(in HostName remote_host, in PortNumber remote_port);
+signature OsmuxEM_mode(in OsmuxemMode mode);
+signature OsmuxEM_configure(in OsmuxemConfig cfg);
+signature OsmuxEM_stats_get(out OsmuxemStats stats);
+signature OsmuxEM_register_rxhandle(in OsmuxRxHandle hdl);
+signature OsmuxEM_register_txhandle(in OsmuxTxHandle hdl);
+
+type port OsmuxEM_CTRL_PT procedure {
+	inout OsmuxEM_bind, OsmuxEM_connect, OsmuxEM_mode, OsmuxEM_configure,
+	      OsmuxEM_stats_get, OsmuxEM_register_rxhandle, OsmuxEM_register_txhandle;
+} with { extension "internal" };
+
+function f_osmuxem_bind(OsmuxEM_CTRL_PT pt, in HostName local_host, inout PortNumber local_port) {
+	pt.call(OsmuxEM_bind:{local_host, local_port}) {
+		[] pt.getreply(OsmuxEM_bind:{local_host, ?}) -> param (local_port) {};
+	}
+}
+function f_osmuxem_connect(OsmuxEM_CTRL_PT pt, in HostName remote_host, in PortNumber remote_port) {
+	pt.call(OsmuxEM_connect:{remote_host, remote_port}) {
+		[] pt.getreply(OsmuxEM_connect:{remote_host, remote_port}) {};
+	}
+}
+function f_osmuxem_mode(OsmuxEM_CTRL_PT pt, in OsmuxemMode mode) {
+	pt.call(OsmuxEM_mode:{mode}) {
+		[] pt.getreply(OsmuxEM_mode:{mode}) {};
+	}
+}
+function f_osmuxem_configure(OsmuxEM_CTRL_PT pt, in OsmuxemConfig cfg) {
+	pt.call(OsmuxEM_configure:{cfg}) {
+		[] pt.getreply(OsmuxEM_configure:{cfg}) {};
+	}
+}
+function f_osmuxem_stats_get(OsmuxEM_CTRL_PT pt) return OsmuxemStats {
+	var OsmuxemStats stats;
+	pt.call(OsmuxEM_stats_get:{-}) {
+		[] pt.getreply(OsmuxEM_stats_get:{?}) -> param(stats) {};
+	}
+	return stats;
+}
+
+function f_osmuxem_register_rxhandle(OsmuxEM_CTRL_PT pt, OsmuxRxHandle hdl) {
+	pt.call(OsmuxEM_register_rxhandle:{hdl}) {
+		[] pt.getreply(OsmuxEM_register_rxhandle:{hdl}) {};
+	}
+}
+
+function f_osmuxem_register_txhandle(OsmuxEM_CTRL_PT pt, OsmuxTxHandle hdl) {
+	pt.call(OsmuxEM_register_txhandle:{hdl}) {
+		[] pt.getreply(OsmuxEM_register_txhandle:{hdl}) {};
+	}
+}
+
+
+function f_osmuxem_stats_compare_value(integer a, integer b, integer tolerance := 0) return boolean {
+	var integer temp;
+
+	temp := (a - b)
+	if (temp < 0) {
+		temp := -temp;
+	}
+
+	if (temp > tolerance) {
+		return false;
+	}
+
+	return true;
+}
+
+/* Cross-compare two osmuxem-statistics. The transmission statistics on the a side
+ * must match the reception statistics on the other side and vice versa. The
+ * user may also supply a tolerance value (number of packets) when deviations
+ * are acceptable */
+function f_osmuxem_stats_compare(OsmuxemStats a, OsmuxemStats b, integer tolerance := 0) return boolean {
+	var integer plen;
+
+	log("stats A: ", a);
+	log("stats B: ", b);
+	log("tolerance: ", tolerance, " packets");
+
+	if (f_osmuxem_stats_compare_value(a.num_pkts_tx, b.num_pkts_rx, tolerance) == false) {
+		return false;
+	}
+
+	if (f_osmuxem_stats_compare_value(a.num_pkts_rx, b.num_pkts_tx, tolerance) == false) {
+		return false;
+	}
+
+	if(a.num_pkts_tx > 0) {
+		plen := a.bytes_payload_tx / a.num_pkts_tx;
+	} else {
+		plen := 0;
+	}
+
+	if (f_osmuxem_stats_compare_value(a.bytes_payload_tx, b.bytes_payload_rx, tolerance * plen) == false) {
+		return false;
+	}
+
+	if (f_osmuxem_stats_compare_value(a.bytes_payload_rx, b.bytes_payload_tx, tolerance * plen) == false) {
+		return false;
+	}
+
+	return true;
+}
+
+/* Check the statistics for general signs of errors. This is a basic general
+ * check that will fit most situations and  is intended to be executed by
+ * the testcases as as needed. */
+function f_osmuxem_stats_err_check(OsmuxemStats s) {
+	log("stats: ", s);
+
+	/* Check if there was some activity at either on the RX or on the
+	 * TX side, but complete silence would indicate some problem */
+	if (s.num_pkts_tx < 1 and s.num_pkts_rx < 1) {
+		setverdict(fail, "no Osmux packet activity detected (packets)");
+		mtc.stop;
+	}
+	if (s.bytes_payload_tx < 1 and s.bytes_payload_rx < 1) {
+		setverdict(fail, "no Osmux packet activity detected (bytes)");
+		mtc.stop;
+	}
+
+	/* Check error counters */
+	if (s.num_pkts_rx_err_seq != 0) {
+		setverdict(fail, "Osmux packet sequence number errors occurred");
+		mtc.stop;
+	}
+	if (s.num_pkts_rx_err_disabled != 0) {
+		setverdict(fail, "Osmux packets received while RX was disabled");
+		mtc.stop;
+	}
+	if (s.num_pkts_rx_err_payload != 0) {
+		setverdict(fail, "Osmux packets with mismatching payload received");
+		mtc.stop;
+	}
+}
+
+template PDU_Osmux_AMR ts_OsmuxAMR(BIT1 marker, INT3b ctr, BIT1 amr_f, BIT1 amr_q, INT1 seq,
+				   OsmuxCID cid, INT4b amr_ft, INT4b amr_cmr,
+				   octetstring payload) := {
+	header := {
+		marker := marker,
+		ft := 1,
+		ctr := ctr,
+		amr_f := amr_f,
+		amr_q := amr_q,
+		seq := seq,
+		cid := cid,
+		amr_ft := amr_ft,
+		amr_cmr := amr_cmr
+	},
+	data := payload
+}
+
+private function f_rxhandle_get_by_cid(OsmuxCID cid) runs on OSMUX_Emulation_CT return OsmuxRxHandle {
+	var integer i;
+	for (i := 0; i < sizeof(RxHandleTable); i := i+1) {
+		if (isbound(RxHandleTable[i].cid) and RxHandleTable[i].cid == cid) {
+			return RxHandleTable[i].vc_conn;
+		}
+	}
+	setverdict(fail, "No Component for CID ", cid);
+	mtc.stop;
+}
+
+private function f_rxhandle_cid_add(OsmuxRxHandle hdl) runs on OSMUX_Emulation_CT {
+	var integer i;
+	for (i := 0; i < sizeof(RxHandleTable); i := i+1) {
+		if (not isbound(RxHandleTable[i].cid)) {
+			RxHandleTable[i].cid := hdl.cid;
+			RxHandleTable[i].vc_conn := hdl;
+			return;
+		}
+	}
+	testcase.stop("No Space in RxHandleTable for ", hdl.cid);
+	mtc.stop;
+}
+
+private function f_txhandle_cid_add(OsmuxTxHandle hdl) runs on OSMUX_Emulation_CT {
+	var integer i;
+	for (i := 0; i < sizeof(TxHandleList); i := i+1) {
+		if (not isbound(TxHandleList[i])) {
+			TxHandleList[i] := hdl;
+			return;
+		}
+	}
+	testcase.stop("No Space in TxHandleList for ", hdl.cid);
+	mtc.stop;
+}
+
+function f_osmux_gen_expected_rx_rtp_payload(INT4b amr_ft, octetstring tx_fixed_payload) return octetstring {
+	var integer payload_len;
+	var octetstring payload_truncated;
+	var integer i;
+	payload_len := f_amrft_payload_len(amr_ft);
+	payload_truncated := substr(tx_fixed_payload, 0, payload_len);
+	return payload_truncated;
+}
+
+private function f_osmux_gen_payload(INT3b ctr, INT4b amr_ft) runs on OSMUX_Emulation_CT return octetstring {
+	var octetstring payload_truncated := ''O;
+	var integer i;
+
+	for (i := 0; i < ctr + 1; i := i+1) {
+		payload_truncated := payload_truncated & f_osmux_gen_expected_rx_rtp_payload(amr_ft, g_cfg.tx_fixed_payload);
+	}
+	return payload_truncated;
+}
+
+private function f_tx_osmux(integer i, INT3b ctr, octetstring payload, BIT1 marker := '0'B) runs on OSMUX_Emulation_CT {
+	var OsmuxTxHandle hdl := TxHandleList[i];
+	var PDU_Osmux_AMR osmux_amr := valueof(ts_OsmuxAMR(marker, ctr, hdl.amr_f,
+					  hdl.amr_q, hdl.seq, hdl.cid, hdl.amr_ft,
+					  hdl.amr_cmr, payload));
+	OSMUX.send(t_Osmux_Send(g_osmux_conn_id, OSMUX_PDU:{osmux_amr:=osmux_amr}));
+	/* increment sequence + timestamp for next transmit */
+	TxHandleList[i].seq := TxHandleList[i].seq + 1;
+
+	/* update counters */
+	g_stat.num_pkts_tx := g_stat.num_pkts_tx+1;
+	g_stat.bytes_payload_tx := g_stat.bytes_payload_tx +
+						lengthof(payload);
+}
+
+private function f_tx_osmux_all_cid(BIT1 marker := '0'B) runs on OSMUX_Emulation_CT {
+	/* TODO: append all in one UDP packet and send together */
+	var integer i;
+	var octetstring payload_truncated;
+	var INT3b ctr := g_cfg.batch_size - 1;
+
+	for (i := 0; i < sizeof(TxHandleList); i := i+1) {
+		if (isbound(TxHandleList[i])) {
+			payload_truncated := f_osmux_gen_payload(ctr, TxHandleList[i].amr_ft);
+			f_tx_osmux(i, ctr, payload_truncated, marker);
+
+		}
+	}
+}
+
+function f_main() runs on OSMUX_Emulation_CT
+{
+	var Result res;
+	var OsmuxRxHandle rx_hdl;
+	var OsmuxTxHandle tx_hdl;
+	var octetstring payload_truncated;
+
+	timer T_transmit := int2float(g_cfg.tx_duration_ms)/1000.0;
+	var Osmux_RecvFrom rx_osmux;
+	var PDU_Osmux_AMR  rx_amr;
+	var PDU_Osmux_DUMMY osmux_dummy;
+	var OsmuxemConfig cfg;
+	var template Osmux_RecvFrom tr_osmux_amr := {
+		connId := ?,
+		remName := ?,
+		remPort := ?,
+		locName := ?,
+		locPort := ?,
+		msg := ?
+	};
+	tr_osmux_amr.msg := { osmux_amr := ? };
+	var template Osmux_RecvFrom tr_osmux_dummy := {
+		connId := ?,
+		remName := ?,
+		remPort := ?,
+		locName := ?,
+		locPort := ?,
+		msg := ?
+	};
+	tr_osmux_dummy.msg := { osmux_dummy := ? };
+
+	while (true) {
+	alt {
+		/* control procedures (calls) from the user */
+		[] CTRL.getcall(OsmuxEM_bind:{?,?}) -> param(g_local_host, g_local_port) {
+
+			g_tx_connected := false; /* will set it back to true upon next connect() call */
+			res := OSMUX_CodecPort_CtrlFunct.f_IPL4_listen(OSMUX, g_local_host,
+								g_local_port, {udp:={}});
+			if (not ispresent(res.connId)) {
+				setverdict(fail, "Could not listen on Osmux socket, check your configuration");
+				mtc.stop;
+			}
+			g_osmux_conn_id := res.connId;
+			tr_osmux_amr.connId := g_osmux_conn_id;
+			tr_osmux_dummy.connId := g_osmux_conn_id;
+
+			CTRL.reply(OsmuxEM_bind:{g_local_host, g_local_port});
+		}
+		[] CTRL.getcall(OsmuxEM_connect:{?,?}) -> param (g_remote_host, g_remote_port) {
+			res := OSMUX_CodecPort_CtrlFunct.f_IPL4_connect(OSMUX, g_remote_host,
+								g_remote_port,
+								g_local_host, g_local_port,
+								g_osmux_conn_id, {udp:={}});
+			if (not ispresent(res.connId)) {
+				setverdict(fail, "Could not connect to Osmux socket, check your configuration");
+				mtc.stop;
+			}
+			g_tx_connected := true;
+			CTRL.reply(OsmuxEM_connect:{g_remote_host, g_remote_port});
+		}
+		[] CTRL.getcall(OsmuxEM_mode:{OSMUXEM_MODE_NONE}) {
+			T_transmit.stop;
+			g_rx_enabled := false;
+			CTRL.reply(OsmuxEM_mode:{OSMUXEM_MODE_NONE});
+		}
+		[] CTRL.getcall(OsmuxEM_mode:{OSMUXEM_MODE_TXONLY}) {
+			/* start transmit timer */
+			T_transmit.start;
+			g_rx_enabled := false;
+			CTRL.reply(OsmuxEM_mode:{OSMUXEM_MODE_TXONLY});
+		}
+		[] CTRL.getcall(OsmuxEM_mode:{OSMUXEM_MODE_RXONLY}) {
+
+			T_transmit.stop;
+			if (g_rx_enabled == false) {
+				/* flush queues */
+				OSMUX.clear;
+				g_rx_enabled := true;
+			}
+			CTRL.reply(OsmuxEM_mode:{OSMUXEM_MODE_RXONLY});
+		}
+		[] CTRL.getcall(OsmuxEM_mode:{OSMUXEM_MODE_BIDIR}) {
+			T_transmit.start;
+			if (g_rx_enabled == false) {
+				/* flush queues */
+				OSMUX.clear;
+				g_rx_enabled := true;
+			}
+			CTRL.reply(OsmuxEM_mode:{OSMUXEM_MODE_BIDIR});
+		}
+		[] CTRL.getcall(OsmuxEM_configure:{?}) -> param (cfg) {
+			g_cfg := cfg;
+			CTRL.reply(OsmuxEM_configure:{cfg});
+		}
+		[] CTRL.getcall(OsmuxEM_register_txhandle:{?}) -> param (tx_hdl) {
+			f_txhandle_cid_add(tx_hdl);
+			CTRL.reply(OsmuxEM_register_txhandle:{tx_hdl});
+		}
+		[] CTRL.getcall(OsmuxEM_register_rxhandle:{?}) -> param (rx_hdl) {
+			f_rxhandle_cid_add(rx_hdl);
+			CTRL.reply(OsmuxEM_register_rxhandle:{rx_hdl});
+		}
+		[] CTRL.getcall(OsmuxEM_stats_get:{?}) {
+				CTRL.reply(OsmuxEM_stats_get:{g_stat});
+		}
+
+		/* simply ignore any Osmux AMR if receiver not enabled */
+		[g_rx_enabled==false] OSMUX.receive(tr_osmux_amr) {
+			g_stat.num_pkts_rx_err_disabled := g_stat.num_pkts_rx_err_disabled+1;
+		}
+		/* simply ignore any Osmux Dummy if receiver not enabled */
+		[g_rx_enabled==false] OSMUX.receive(tr_osmux_dummy) -> value rx_osmux {
+			log("Osmux Dummy received on CID ", rx_osmux.msg.osmux_dummy.header.cid, " (rx_disabled)");
+		}
+
+		/* process received Osmux AMR if receiver enabled */
+		[g_rx_enabled] OSMUX.receive(tr_osmux_amr) -> value rx_osmux {
+			/* increment counters */
+			g_stat.num_pkts_rx := g_stat.num_pkts_rx+1;
+			g_stat.bytes_payload_rx := g_stat.bytes_payload_rx +
+								lengthof(rx_osmux.msg.osmux_amr.data);
+			rx_hdl := f_rxhandle_get_by_cid(rx_osmux.msg.osmux_amr.header.cid);
+
+			if (rx_hdl.first_seq_seen and rx_hdl.last_seq_ack != rx_osmux.msg.osmux_amr.header.seq - 1 ) {
+				g_stat.num_pkts_rx_err_seq := g_stat.num_pkts_rx_err_seq + 1;
+			}
+			rx_hdl.first_seq_seen := true;
+			rx_hdl.last_seq_ack := rx_osmux.msg.osmux_amr.header.seq;
+
+			payload_truncated := f_osmux_gen_payload(rx_osmux.msg.osmux_amr.header.ctr, rx_osmux.msg.osmux_amr.header.amr_ft);
+			if (ispresent(g_cfg.rx_fixed_payload) and rx_osmux.msg.osmux_amr.data != payload_truncated) {
+				g_stat.num_pkts_rx_err_payload := g_stat.num_pkts_rx_err_payload + 1;
+			}
+		}
+		/* process received Osmux Dummy if receiver enabled */
+		[g_rx_enabled] OSMUX.receive(tr_osmux_dummy) -> value rx_osmux {
+			log("Osmux Dummy received on CID", rx_osmux.msg.osmux_dummy.header.cid);
+			rx_hdl := f_rxhandle_get_by_cid(rx_osmux.msg.osmux_dummy.header.cid);
+		}
+
+		/* transmit if timer has expired */
+		[g_tx_connected] T_transmit.timeout {
+			/* send one Osmux frame, re-start timer */
+			f_tx_osmux_all_cid();
+			T_transmit.start;
+		}
+
+		/* fail on any unexpected messages */
+		[] OSMUX.receive {
+			setverdict(fail, "Received unexpected type from Osmux");
+			mtc.stop;
+		}
+	}
+	}
+}
+
+
+}
diff --git a/library/OSMUX_Types.ttcn b/library/OSMUX_Types.ttcn
new file mode 100644
index 0000000..091b4d7
--- /dev/null
+++ b/library/OSMUX_Types.ttcn
@@ -0,0 +1,110 @@
+/*
+ * (C) 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * All rights reserved.
+ *
+ * Author: Pau Espin Pedrol <pespin@sysmocom.de>
+ *
+ * Released under the terms of GNU General Public License, Version 2 or
+ * (at your option) any later version.
+ */
+
+module OSMUX_Types {
+
+import from General_Types all;
+
+external function enc_OSMUX_PDU ( in OSMUX_PDU msg ) return octetstring
+        with { extension "prototype(convert) encode(RAW)" };
+external function dec_OSMUX_PDU ( in octetstring msg ) return OSMUX_PDU
+        with { extension "prototype(convert) decode(RAW)" };
+
+type INT1 OsmuxCID	(0 .. 255);
+
+type enumerated OsmuxFT {
+  OSMUX_FT_LAPD,
+  OSMUX_FT_AMR,
+  OSMUX_FT_DUMMY
+};
+
+type record Osmux_AMR_header {
+  BIT1                 marker,
+  INT2b                ft,
+  INT3b                ctr,
+  BIT1                 amr_f,
+  BIT1                 amr_q,
+  INT1                 seq,
+  OsmuxCID             cid,
+  INT4b                amr_ft,
+  INT4b                amr_cmr
+} with {
+  variant "FIELDORDER(msb)"
+}
+
+type record PDU_Osmux_AMR {
+  Osmux_AMR_header     header,
+  octetstring          data
+} with {
+  variant "FIELDORDER(msb)"
+};
+
+type record PDU_Osmux_DUMMY {
+  Osmux_AMR_header     header,
+  octetstring          data
+} with {
+  variant "FIELDORDER(msb)"
+};
+
+type record Osmux_session_par {
+  integer               id optional,
+  charstring            local_address optional,
+  integer               local_port optional,
+  charstring            dest_address optional,
+  integer               dest_port optional
+}
+
+type record ASP_Osmux_Open_session {
+  Osmux_session_par       session_id
+}
+
+type record ASP_Osmux_Open_session_result {
+  Osmux_session_par       session_id
+}
+
+type record ASP_Osmux_Close_session {
+  Osmux_session_par       session_id
+}
+
+type union OSMUX_PDU {
+  PDU_Osmux_AMR               osmux_amr,
+  PDU_Osmux_DUMMY             osmux_dummy
+} with {
+  variant "TAG (
+    osmux_amr, header.ft = 1;
+    osmux_dummy, header.ft = 2;
+  )"
+};
+
+
+/* AMR voice frame type identifiers
+ * See also 3GPP TS 26.101, Table 1a: Interpretation of Frame Type, Mode
+ * Indication and Mode Request fields */
+type enumerated AMRFT {
+  AMR_FT_0,	/* 4.75 */
+  AMR_FT_1,	/* 5.15 */
+  AMR_FT_2,	/* 5.90 */
+  AMR_FT_3,	/* 6.70 */
+  AMR_FT_4,	/* 7.40 */
+  AMR_FT_5,	/* 7.95 */
+  AMR_FT_6,	/* 10.2 */
+  AMR_FT_7,	/* 12.2 */
+  AMR_FT_SID	/* SID */
+};
+
+/* AMR voice frame length (in bytes, rounded),
+ * See also RFC 3267, chapter 3.6 */
+const integer c_AMRFT_len[9] := {12, 13, 15, 17, 19, 20, 26, 31, 5};
+
+function f_amrft_payload_len(INT4b amr_ft) return integer {
+        return c_AMRFT_len[amr_ft];
+}
+
+} with { encode "RAW"}
diff --git a/mgw/MGCP_Test.ttcn b/mgw/MGCP_Test.ttcn
index 8cb2404..ec3070e 100644
--- a/mgw/MGCP_Test.ttcn
+++ b/mgw/MGCP_Test.ttcn
@@ -8,6 +8,10 @@
 	import from RTP_CodecPort all;
 	import from RTP_CodecPort_CtrlFunct all;
 	import from RTP_Emulation all;
+	import from OSMUX_Types all;
+	import from OSMUX_CodecPort all;
+	import from OSMUX_CodecPort_CtrlFunct all;
+	import from OSMUX_Emulation all;
 	import from IPL4asp_Types all;
 	import from General_Types all;
 	import from Native_Functions all;
@@ -31,6 +35,9 @@
 		var RTP_Emulation_CT vc_RTPEM[3];
 		port RTPEM_CTRL_PT RTPEM[3];
 
+		var OSMUX_Emulation_CT vc_OsmuxEM;
+		port OsmuxEM_CTRL_PT OsmuxEM;
+
 		port TELNETasp_PT MGWVTY;
 	};
 
@@ -50,12 +57,29 @@
 		PortNumber mp_remote_udp_port := 2427;
 		charstring mp_remote_ip := "127.0.0.1";
 		PortNumber mp_local_rtp_port_base := 10000;
+		PortNumber mp_local_osmux_port := 1985;
 	}
 
-	private function f_init_vty() runs on dummy_CT {
+	private function f_vty_enable_osmux(boolean osmux_on) runs on dummy_CT {
+		/* Turn on conversion mode */
+		f_vty_enter_config(MGWVTY);
+		f_vty_transceive(MGWVTY, "mgcp");
+		if (osmux_on) {
+			f_vty_transceive(MGWVTY, "osmux on");
+		} else {
+			f_vty_transceive(MGWVTY, "osmux off");
+		}
+		f_vty_transceive(MGWVTY, "exit");
+		f_vty_transceive(MGWVTY, "exit");
+
+	}
+
+	private function f_init_vty(boolean osmux_on) runs on dummy_CT {
 		map(self:MGWVTY, system:MGWVTY);
 		f_vty_set_prompts(MGWVTY);
 		f_vty_transceive(MGWVTY, "enable");
+
+		f_vty_enable_osmux(osmux_on);
 	}
 
 	private function f_rtpem_init(inout RTP_Emulation_CT comp_ref, integer i)
@@ -66,10 +90,17 @@
 		comp_ref.start(RTP_Emulation.f_main());
 	}
 
+	private function f_osmuxem_init(inout OSMUX_Emulation_CT comp_ref)
+	runs on dummy_CT {
+		comp_ref := OSMUX_Emulation_CT.create("OsmuxEM");
+		map(comp_ref:OSMUX, system:OSMUX);
+		comp_ref.start(OSMUX_Emulation.f_main());
+	}
+
 	/* initialization function, called by each test case at the
 	 * beginning, but 'initialized' variable ensures its body is
 	 * only executed once */
-	private function f_init(template MgcpEndpoint ep := omit) runs on dummy_CT {
+	private function f_init(template MgcpEndpoint ep := omit, boolean osmux_on := false) runs on dummy_CT {
 		var Result res;
 		var uint32_t ssrc;
 
@@ -93,6 +124,10 @@
 				f_rtpem_init(vc_RTPEM[i], i);
 				connect(vc_RTPEM[i]:CTRL, self:RTPEM[i]);
 			}
+			if (osmux_on) {
+				f_osmuxem_init(vc_OsmuxEM);
+				connect(vc_OsmuxEM:CTRL, self:OsmuxEM);
+			}
 		}
 
 		if (isvalue(ep)) {
@@ -100,7 +135,7 @@
 			f_dlcx_ignore(valueof(ep));
 		}
 
-		f_init_vty();
+		f_init_vty(osmux_on);
 	}
 
 	testcase TC_selftest() runs on dummy_CT {
@@ -272,6 +307,10 @@
 		charstring codec,
 		MgcpConnectionId mgcp_conn_id optional,
 		RtpemConfig rtp_cfg optional,
+		boolean osmux_cid_sent, /* whther non wildcarded CID was already sent to MGW */
+		MgcpOsmuxCID osmux_cid optional,
+		MgcpOsmuxCID osmux_cid_response optional,
+		OsmuxemConfig osmux_cfg optional,
 		charstring fmtp optional
 	}
 
@@ -333,6 +372,91 @@
 		f_rtpem_connect(pt, flow.mgw.hostname, flow.mgw.portnr);
 	}
 
+	/* Create an Osmux flow (bidirectional, or receive-only) */
+	function f_flow_create_osmux(OsmuxEM_CTRL_PT pt, MgcpEndpoint ep, MgcpCallId call_id, charstring mode, inout RtpFlowData flow,
+				boolean one_phase := true)
+	runs on dummy_CT {
+		var template MgcpCommand cmd;
+		var MgcpResponse resp;
+		var SDP_attribute_list attributes;
+		var OsmuxTxHandle tx_hdl;
+		var OsmuxRxHandle rx_hdl;
+		var charstring cid_response;
+		var OsmuxCID cid_resp_parsed
+
+		attributes := { valueof(ts_SDP_rtpmap(flow.pt, flow.codec)), valueof(ts_SDP_ptime(20)) };
+		if (isvalue(flow.fmtp)) {
+			attributes := attributes & { valueof(ts_SDP_fmtp(flow.pt, flow.fmtp)) };
+		}
+
+		/* bind local Osmux emulation socket */
+		f_osmuxem_bind(pt, flow.em.hostname, flow.em.portnr);
+
+		/* configure osmux-emulation */
+		if (ispresent(flow.osmux_cfg)) {
+			f_osmuxem_configure(pt, flow.osmux_cfg);
+		} else {
+			var OsmuxemConfig osmux_cfg := c_OsmuxemDefaultCfg;
+			f_osmuxem_configure(pt, osmux_cfg);
+			flow.osmux_cfg := osmux_cfg
+		}
+
+		if (one_phase) {
+			/* Connect flow to MGW using a CRCX that also contains an SDP
+			 * part that tells the MGW where we are listening for Osmux streams
+			 * that come from the MGW. We get a fully working connection in
+			 * one go. */
+			rx_hdl := c_OsmuxemDefaultRxHandle;
+			rx_hdl.cid := flow.osmux_cid;
+			f_osmuxem_register_rxhandle(pt, rx_hdl);
+			flow.osmux_cid_sent := true;
+			cmd := ts_CRCX_osmux(get_next_trans_id(), ep, mode, call_id, flow.osmux_cid);
+			cmd.sdp := ts_SDP(flow.em.hostname, flow.em.hostname, "23", "42",
+					  flow.em.portnr, { int2str(flow.pt) }, attributes);
+  			resp := mgcp_transceive_mgw(cmd, tr_CRCX_ACK_osmux);
+			flow.mgcp_conn_id := extract_conn_id(resp);
+			/* extract port number from response */
+			flow.mgw.portnr :=
+				resp.sdp.media_list[0].media_field.ports.port_number;
+		} else {
+			/* Create a half-open connection only. We do not tell the MGW
+			 * where it can send Osmux streams to us. This means this
+			 * connection will only be able to receive but can not send
+			 * data back to us. In order to turn the connection in a fully
+			 * bi-directional one, a separate MDCX is needed. */
+
+			cmd := ts_CRCX_osmux(get_next_trans_id(), ep, mode, call_id, flow.osmux_cid);
+			resp := mgcp_transceive_mgw(cmd, tr_CRCX_ACK_osmux);
+
+			flow.mgcp_conn_id := extract_conn_id(resp);
+			/* extract MGW-side port number from response */
+			flow.mgw.portnr :=
+				resp.sdp.media_list[0].media_field.ports.port_number;
+		}
+
+		/* extract Osmux CID we got assigned by the MGW */
+		var MgcpMessage resp_msg := {
+			response := resp
+		}
+
+		if (f_mgcp_find_param(resp_msg, "X-OSMUX", cid_response) == false) {
+			setverdict(fail, "No Osmux CID in MGCP response", resp);
+			mtc.stop;
+		}
+
+		/* Make sure response is no wildcard */
+		flow.osmux_cid_response := f_mgcp_osmux_cid_decode(cid_response);
+		if (flow.osmux_cid_response == -1) {
+			setverdict(fail, "Osmux CID in MGCP response contains unexpected wildcard");
+			mtc.stop;
+		}
+		tx_hdl := valueof(t_TxHandleAMR590(flow.osmux_cid_response));
+		f_osmuxem_register_txhandle(pt, tx_hdl);
+
+		/* finally, connect the emulation-side RTP socket to the MGW */
+		f_osmuxem_connect(pt, flow.mgw.hostname, flow.mgw.portnr);
+	}
+
 	/* Modify an existing RTP flow */
 	function f_flow_modify(RTPEM_CTRL_PT pt, MgcpEndpoint ep, MgcpCallId call_id, charstring mode, inout RtpFlowData flow)
 	runs on dummy_CT {
@@ -372,6 +496,76 @@
 		f_rtpem_connect(pt, flow.mgw.hostname, flow.mgw.portnr);
 	}
 
+	/* Modify an existing Osmux flow */
+	function f_flow_modify_osmux(OsmuxEM_CTRL_PT pt, MgcpEndpoint ep, MgcpCallId call_id, charstring mode, inout RtpFlowData flow)
+	runs on dummy_CT {
+		var template MgcpCommand cmd;
+		var MgcpResponse resp;
+		var SDP_attribute_list attributes;
+		var OsmuxRxHandle rx_hdl;
+		var charstring cid_response;
+		var OsmuxCID cid_resp_parsed
+
+		attributes := { valueof(ts_SDP_rtpmap(flow.pt, flow.codec)), valueof(ts_SDP_ptime(20)) };
+		if (isvalue(flow.fmtp)) {
+			attributes := attributes & { valueof(ts_SDP_fmtp(flow.pt, flow.fmtp)) };
+		}
+
+		/* rebind local Osmux emulation socket to the new address */
+		f_osmuxem_bind(pt, flow.em.hostname, flow.em.portnr);
+
+		/* configure osmux-emulation */
+		if (ispresent(flow.osmux_cfg)) {
+			f_osmuxem_configure(pt, flow.osmux_cfg);
+		} else {
+			var OsmuxemConfig osmux_cfg := c_OsmuxemDefaultCfg;
+			f_osmuxem_configure(pt, osmux_cfg);
+		}
+
+		/* We didn't send a non-wildcarded Osmux CID yet. If caller wants to submit it, register handler */
+		if (flow.osmux_cid_sent == false and flow.osmux_cid != -1) {
+			rx_hdl := c_OsmuxemDefaultRxHandle;
+			rx_hdl.cid := flow.osmux_cid;
+			f_osmuxem_register_rxhandle(pt, rx_hdl);
+			flow.osmux_cid_sent := true;
+		}
+
+		/* connect MGW side Osmux socket to the emulation-side Osmux socket using SDP */
+		cmd := ts_MDCX_osmux(get_next_trans_id(), ep, mode, call_id, flow.mgcp_conn_id, flow.osmux_cid);
+		cmd.sdp := ts_SDP(flow.em.hostname, flow.em.hostname, "23", "42",
+				  flow.em.portnr, { int2str(flow.pt) }, attributes);
+		resp := mgcp_transceive_mgw(cmd, tr_MDCX_ACK);
+
+		/* extract MGW-side port number from response. (usually this
+		 * will not change, but thats is up to the MGW) */
+		flow.mgw.portnr :=
+			resp.sdp.media_list[0].media_field.ports.port_number;
+
+		/* extract Osmux CID we got assigned by the MGW */
+		var MgcpMessage resp_msg := {
+			response := resp
+		}
+
+		if (f_mgcp_find_param(resp_msg, "X-OSMUX", cid_response) == false) {
+			setverdict(fail, "No Osmux CID in MGCP response", resp);
+			mtc.stop;
+		}
+
+		/* Make sure response is no wildcard */
+		cid_resp_parsed := f_mgcp_osmux_cid_decode(cid_response);
+		if (cid_resp_parsed == -1) {
+			setverdict(fail, "Osmux CID in MGCP response contains unexpected wildcard");
+			mtc.stop;
+		}
+		if (cid_resp_parsed != flow.osmux_cid_response) {
+			setverdict(fail, "Osmux CID in MGCP MDCX response changed from prev value");
+			mtc.stop;
+		}
+
+		/* reconnect the emulation-side Osmux socket to the MGW */
+		f_osmuxem_connect(pt, flow.mgw.hostname, flow.mgw.portnr);
+	}
+
 	/* Delete an existing RTP flow */
 	function f_flow_delete(RTPEM_CTRL_PT pt, template MgcpEndpoint ep := omit, template MgcpCallId call_id := omit)
 	runs on dummy_CT {
@@ -388,6 +582,22 @@
 		}
 	}
 
+	/* Delete an existing Osmux flow */
+	function f_flow_delete_osmux(OsmuxEM_CTRL_PT pt, template MgcpEndpoint ep := omit, template MgcpCallId call_id := omit)
+	runs on dummy_CT {
+		var template MgcpCommand cmd;
+		var MgcpResponse resp;
+
+		/* Switch off Osmux flow */
+		f_osmuxem_mode(pt, OSMUXEM_MODE_NONE);
+
+		/* Delete connection on MGW (if needed) */
+		if (isvalue(call_id) and isvalue(ep)) {
+			f_sleep(0.1);
+			f_dlcx_ok(valueof(ep), call_id);
+		}
+	}
+
 	function f_crcx(charstring ep_prefix) runs on dummy_CT {
 		var MgcpEndpoint ep := ep_prefix & "2@" & c_mgw_domain;
 		var template MgcpCommand cmd;
@@ -437,6 +647,42 @@
 		}
 	}
 
+	function f_crcx_osmux(charstring ep_prefix, MgcpOsmuxCID osmux_cid, boolean run_init := true) runs on dummy_CT {
+		var MgcpEndpoint ep := ep_prefix & "2@" & c_mgw_domain;
+		var template MgcpCommand cmd;
+		var MgcpResponse resp;
+		var MgcpCallId call_id := '1234'H;
+		var charstring cid_response;
+
+		if (run_init) {
+			f_init(ep, true);
+		}
+
+		/* create the connection on the MGW */
+		cmd := ts_CRCX_osmux(get_next_trans_id(), ep, "recvonly", call_id, osmux_cid);
+		resp := mgcp_transceive_mgw(cmd, tr_CRCX_ACK_osmux);
+		extract_conn_id(resp);
+
+		/* extract Osmux CID we got assigned by the MGW */
+		var MgcpMessage resp_msg := {
+			response := resp
+		}
+
+		if (f_mgcp_find_param(resp_msg, "X-OSMUX", cid_response) == false) {
+			setverdict(fail, "No Osmux CID in MGCP response", resp);
+			mtc.stop;
+		}
+
+		/* Make sure response is no wildcard */
+		if (f_mgcp_osmux_cid_decode(cid_response) == -1) {
+			setverdict(fail, "Osmux CID in MGCP response contains unexpected wildcard");
+			mtc.stop;
+		}
+
+		/* clean-up */
+		f_dlcx_ok(ep, call_id);
+	}
+
 	/* test valid CRCX without SDP */
 	testcase TC_crcx() runs on dummy_CT {
 		f_crcx(c_mgw_ep_rtpbridge);
@@ -791,6 +1037,358 @@
 		setverdict(pass);
 	}
 
+	/* test valid CRCX without SDP */
+	testcase TC_crcx_osmux_wildcard() runs on dummy_CT {
+		f_crcx_osmux(c_mgw_ep_rtpbridge, -1);
+		setverdict(pass);
+	}
+
+	/* test valid CRCX without SDP */
+	testcase TC_crcx_osmux_fixed() runs on dummy_CT {
+		f_crcx_osmux(c_mgw_ep_rtpbridge, 2);
+		setverdict(pass);
+	}
+
+	/* test valid CRCX without SDP, twice, to make sure CID is freed fine during first step. */
+	testcase TC_crcx_osmux_fixed_twice() runs on dummy_CT {
+		f_crcx_osmux(c_mgw_ep_rtpbridge, 3, true);
+		f_crcx_osmux(c_mgw_ep_rtpbridge, 3, false);
+		setverdict(pass);
+	}
+
+	/* Create one half open connection in receive-only mode. The MGW must accept
+	 * the packets but must not send any. */
+	testcase TC_one_crcx_receive_only_osmux() runs on dummy_CT {
+		var RtpFlowData flow;
+		var MgcpEndpoint ep := c_mgw_ep_rtpbridge & "1@" & c_mgw_domain;
+		var MgcpCallId call_id := '1225'H;
+		var OsmuxemStats stats;
+		var OsmuxTxHandle tx_hdl;
+
+		f_init(ep, true);
+		flow := valueof(t_RtpFlow(mp_local_ip, mp_remote_ip, 112, "AMR/8000/1"));
+		flow.em.portnr := mp_local_osmux_port;
+		flow.osmux_cid := -1;
+		f_flow_create_osmux(OsmuxEM, ep, call_id, "recvonly", flow, false);
+
+		/* create a transmitter not yet known by MGW */
+		tx_hdl := valueof(t_TxHandleAMR590(2));
+		f_osmuxem_register_txhandle(OsmuxEM, tx_hdl);
+
+		f_osmuxem_mode(OsmuxEM, OSMUXEM_MODE_TXONLY);
+		f_sleep(1.0);
+		f_flow_delete_osmux(OsmuxEM, ep, call_id);
+
+		stats := f_osmuxem_stats_get(OsmuxEM);
+
+		if (stats.num_pkts_tx < 40 / flow.osmux_cfg.batch_size) {
+			setverdict(fail);
+		}
+		if (stats.bytes_payload_tx < stats.num_pkts_tx * f_amrft_payload_len(tx_hdl.amr_ft) * flow.osmux_cfg.batch_size) {
+			setverdict(fail);
+		}
+
+		f_osmuxem_stats_err_check(stats);
+
+		setverdict(pass);
+	}
+
+	/* Create one connection in loopback mode, test if the Osmux packets are
+	 * actually reflected */
+	testcase TC_one_crcx_loopback_osmux() runs on dummy_CT {
+		var RtpFlowData flow;
+		var MgcpEndpoint ep := c_mgw_ep_rtpbridge & "1@" & c_mgw_domain;
+		var MgcpCallId call_id := '1225'H;
+		var OsmuxemStats stats;
+		var OsmuxTxHandle tx_hdl;
+
+		f_init(ep, true);
+		flow := valueof(t_RtpFlow(mp_local_ip, mp_remote_ip, 111, "GSM-HR-08/8000/1"));
+		flow.em.portnr := mp_local_osmux_port;
+		flow.osmux_cid := 2;
+		f_flow_create_osmux(OsmuxEM, ep, call_id, "loopback", flow);
+
+		f_osmuxem_mode(OsmuxEM, OSMUXEM_MODE_BIDIR);
+		f_sleep(1.0);
+
+		/* Switch off both Tx, wait to receive delayed frames from MGW */
+		f_osmuxem_mode(OsmuxEM, OSMUXEM_MODE_RXONLY);
+		f_sleep(0.1);
+		f_flow_delete_osmux(OsmuxEM, ep, call_id);
+
+		stats := f_osmuxem_stats_get(OsmuxEM);
+
+		if (stats.num_pkts_tx != stats.num_pkts_rx) {
+			setverdict(fail);
+		}
+		if (stats.bytes_payload_tx != stats.bytes_payload_rx) {
+			setverdict(fail);
+		}
+
+		f_osmuxem_stats_err_check(stats);
+
+		setverdict(pass);
+	}
+
+	/* Cross-compare two osmuxem-statistics. The transmission statistics on the a side
+	 * must match the reception statistics on the other side and vice versa. The
+	 * user may also supply a tolerance value (number of packets) when deviations
+	 * are acceptable */
+	function f_rtp_osmux_stats_compare(RtpemStats a, OsmuxemStats b, integer batch_size, integer tolerance := 0) return boolean {
+		var integer plen;
+
+		log("stats A: ", a);
+		log("stats B: ", b);
+		log("tolerance: ", tolerance, " packets");
+		log("batch_size: ", batch_size, " packets");
+
+		var integer tolerance_batch := tolerance + (batch_size - tolerance mod batch_size);
+
+		if (f_osmuxem_stats_compare_value(a.num_pkts_tx, b.num_pkts_rx * batch_size, tolerance_batch) == false) {
+			return false;
+		}
+
+		if (f_osmuxem_stats_compare_value(a.num_pkts_rx / batch_size, b.num_pkts_tx, tolerance_batch) == false) {
+			return false;
+		}
+
+		if(a.num_pkts_tx > 0) {
+			plen := a.bytes_payload_tx / a.num_pkts_tx;
+		} else {
+			plen := 0;
+		}
+
+		/* Each RTP pcket payload contains 2 extra bytes due to AMR ToC at start */
+		if (f_osmuxem_stats_compare_value(a.bytes_payload_tx, b.bytes_payload_rx + a.num_pkts_tx * 2, tolerance_batch * plen) == false) {
+			log("incorrect payload A->B: " , a.bytes_payload_tx, " vs ", b.bytes_payload_rx + a.num_pkts_rx * 2);
+			return false;
+		}
+
+		if (f_osmuxem_stats_compare_value(a.bytes_payload_rx, b.bytes_payload_tx + b.num_pkts_tx * 2 * batch_size, tolerance_batch * plen) == false) {
+			log("incorrect payload B->A: " ,  b.bytes_payload_tx + b.num_pkts_tx * 2 * batch_size, " vs ", a.bytes_payload_rx);
+			return false;
+		}
+
+		return true;
+	}
+
+	function f_TC_two_crcx_and_rtp_osmux(boolean bidir) runs on dummy_CT {
+		var RtpFlowData flow[2];
+		var RtpemStats stats_rtp;
+		var OsmuxemStats stats_osmux;
+		var MgcpResponse resp;
+		var MgcpEndpoint ep := c_mgw_ep_rtpbridge & "2@" & c_mgw_domain;
+		var MgcpCallId call_id := '1226'H;
+		var integer tolerance := 0;
+
+		f_init(ep, true);
+
+		/* from us to MGW */
+		flow[0] := valueof(t_RtpFlow(mp_local_ip, mp_remote_ip, 112, "AMR/8000"));
+		flow[0].rtp_cfg := c_RtpemDefaultCfg
+		flow[0].rtp_cfg.tx_payload_type := flow[0].pt;
+		/* 0014 is the ToC (CMR=AMR4.75) in front of AMR Payload in RTP Payload */
+		flow[0].rtp_cfg.rx_fixed_payload := '0014'O & f_osmux_gen_expected_rx_rtp_payload(2 /* AMR_FT_2, 5.90 */, c_OsmuxemDefaultCfg.tx_fixed_payload);
+		flow[0].rtp_cfg.tx_fixed_payload := flow[0].rtp_cfg.rx_fixed_payload;
+		/* bind local RTP emulation sockets */
+		flow[0].em.portnr := 10000;
+		f_flow_create(RTPEM[0], ep, call_id, "sendrecv", flow[0]);
+
+		/* from MGW back to us */
+		flow[1] := valueof(t_RtpFlow(mp_local_ip, mp_remote_ip, 110, "AMR/8000"));
+		flow[1].em.portnr := mp_local_osmux_port;
+		flow[1].osmux_cid := 2;
+		flow[1].osmux_cfg := c_OsmuxemDefaultCfg;
+		f_flow_create_osmux(OsmuxEM, ep, call_id, "sendrecv", flow[1]);
+
+		if (bidir) {
+				f_rtpem_mode(RTPEM[0], RTPEM_MODE_BIDIR);
+				f_osmuxem_mode(OsmuxEM, OSMUXEM_MODE_BIDIR);
+
+				/* Note: When we test bidirectional we may
+				 * loose packets during switch off because
+				 * both ends are transmitting and we only
+				 * can switch them off one by one. */
+				tolerance := 3;
+		} else {
+				f_rtpem_mode(RTPEM[0], RTPEM_MODE_RXONLY);
+				f_osmuxem_mode(OsmuxEM, OSMUXEM_MODE_TXONLY);
+		}
+
+		f_sleep(1.0);
+
+		/* Switch off both Tx, wait to receive delayed frames from MGW */
+		f_rtpem_mode(RTPEM[0], RTPEM_MODE_RXONLY);
+		f_osmuxem_mode(OsmuxEM, OSMUXEM_MODE_RXONLY);
+		f_sleep(0.1);
+
+		f_flow_delete_osmux(OsmuxEM, ep, call_id);
+		f_flow_delete(RTPEM[1]);
+
+		stats_rtp := f_rtpem_stats_get(RTPEM[0]);
+		stats_osmux := f_osmuxem_stats_get(OsmuxEM);
+		if (not f_rtp_osmux_stats_compare(stats_rtp, stats_osmux, flow[1].osmux_cfg.batch_size,  tolerance)) {
+			setverdict(fail, "RTP and Osmux endpoint statistics don't match");
+			mtc.stop;
+		}
+
+		f_rtpem_stats_err_check(stats_rtp);
+		f_osmuxem_stats_err_check(stats_osmux);
+
+		setverdict(pass);
+	}
+
+	/* create one RTP and one OSmux emulations; create two connections on MGW EP, exchange some data */
+	testcase TC_two_crcx_and_rtp_osmux() runs on dummy_CT {
+		 f_TC_two_crcx_and_rtp_osmux(false);
+	}
+
+	/* create one RTP and one OSmux emulations; create two connections on MGW EP,
+	 * exchange some data in both directions */
+	testcase TC_two_crcx_and_rtp_osmux_bidir() runs on dummy_CT {
+		 f_TC_two_crcx_and_rtp_osmux(true);
+	}
+
+
+	function f_two_crcx_mdcx_and_rtp_osmux(boolean crcx_osmux_wildcard) runs on dummy_CT {
+		var RtpFlowData flow[2];
+		var RtpemStats stats_rtp;
+		var OsmuxemStats stats_osmux;
+		var MgcpResponse resp;
+		var MgcpEndpoint ep := c_mgw_ep_rtpbridge & "2@" & c_mgw_domain;
+		var MgcpCallId call_id := '1227'H;
+		var integer num_pkts_tx[2];
+		var integer temp;
+
+		f_init(ep, true);
+
+		/* Create the first connection in receive only mode */
+		flow[0] := valueof(t_RtpFlow(mp_local_ip, mp_remote_ip, 112, "AMR/8000"));
+		flow[0].rtp_cfg := c_RtpemDefaultCfg
+		flow[0].rtp_cfg.tx_payload_type := flow[0].pt;
+		/* 0014 is the ToC (CMR=AMR4.75) in front of AMR Payload in RTP Payload */
+		flow[0].rtp_cfg.rx_fixed_payload := '0014'O & f_osmux_gen_expected_rx_rtp_payload(2 /* AMR_FT_2, 5.90 */, c_OsmuxemDefaultCfg.tx_fixed_payload);
+		flow[0].rtp_cfg.tx_fixed_payload := flow[0].rtp_cfg.rx_fixed_payload;
+		/* bind local RTP emulation sockets */
+		flow[0].em.portnr := 10000;
+		f_flow_create(RTPEM[0], ep, call_id, "recvonly", flow[0], false);
+
+
+		/* Create the second connection. This connection will be also
+		 * in receive only mode */
+		flow[1] := valueof(t_RtpFlow(mp_local_ip, mp_remote_ip, 110, "AMR/8000"));
+		flow[1].em.portnr := mp_local_osmux_port;
+		if (crcx_osmux_wildcard) {
+			flow[1].osmux_cid := -1;
+		} else {
+			flow[1].osmux_cid := 2;
+		}
+		flow[1].osmux_cfg := c_OsmuxemDefaultCfg;
+		f_flow_create_osmux(OsmuxEM, ep, call_id, "recvonly", flow[1], false);
+
+
+		/* The first leg starts transmitting */
+		f_rtpem_mode(RTPEM[0], RTPEM_MODE_TXONLY);
+		f_sleep(0.5);
+		stats_rtp := f_rtpem_stats_get(RTPEM[0]);
+		if (stats_rtp.num_pkts_rx_err_disabled != 0) {
+			setverdict(fail, "received packets from RTP MGW on recvonly connection");
+			mtc.stop;
+		}
+		stats_osmux := f_osmuxem_stats_get(OsmuxEM);
+		if (stats_osmux.num_pkts_rx_err_disabled != 0) {
+			setverdict(fail, "received packets from Osmux MGW on recvonly connection");
+			mtc.stop;
+		}
+
+		/* The second leg starts transmitting a little later */
+		f_osmuxem_mode(OsmuxEM, OSMUXEM_MODE_TXONLY);
+		f_sleep(1.0);
+		stats_rtp := f_rtpem_stats_get(RTPEM[0]);
+		if (stats_rtp.num_pkts_rx_err_disabled != 0) {
+			setverdict(fail, "received packets from RTP MGW on recvonly connection");
+			mtc.stop;
+		}
+		stats_osmux := f_osmuxem_stats_get(OsmuxEM);
+		if (stats_osmux.num_pkts_rx_err_disabled != 0) {
+			setverdict(fail, "received packets from Osmux MGW on recvonly connection");
+			mtc.stop;
+		}
+
+		/* The first leg will now be switched into bidirectional
+		 * mode, but we do not expect any data comming back yet. */
+		f_flow_modify(RTPEM[0], ep, call_id, "sendrecv", flow[0]);
+		f_sleep(0.5);
+		stats_rtp := f_rtpem_stats_get(RTPEM[0]);
+		if (stats_rtp.num_pkts_rx_err_disabled != 0) {
+			setverdict(fail, "received packets from RTP MGW on recvonly connection");
+			mtc.stop;
+		}
+		stats_osmux := f_osmuxem_stats_get(OsmuxEM);
+		if (stats_osmux.num_pkts_rx_err_disabled != 0) {
+			setverdict(fail, "received packets from Osmux MGW on recvonly connection");
+			mtc.stop;
+		}
+
+		/* When the second leg is switched into bidirectional mode
+		 * as well, then the MGW will connect the two together and
+		 * we should see RTP streams passing through from both ends. */
+		f_rtpem_mode(RTPEM[0], RTPEM_MODE_BIDIR);
+		f_osmuxem_mode(OsmuxEM, OSMUXEM_MODE_BIDIR);
+		stats_rtp := f_rtpem_stats_get(RTPEM[0]);
+		num_pkts_tx[0] := stats_rtp.num_pkts_tx
+		stats_osmux := f_osmuxem_stats_get(OsmuxEM);
+		num_pkts_tx[1] := stats_osmux.num_pkts_tx
+
+		if (crcx_osmux_wildcard) {
+			/* For now we must set same CID as the MGW recvCID,
+			 * having sendCID!=recvCID is not yet supported. */
+			flow[1].osmux_cid := flow[1].osmux_cid_response;
+		}
+		f_flow_modify_osmux(OsmuxEM, ep, call_id, "sendrecv", flow[1]);
+		f_sleep(2.0);
+
+		stats_rtp := f_rtpem_stats_get(RTPEM[0]);
+		stats_osmux := f_osmuxem_stats_get(OsmuxEM);
+
+		temp := stats_rtp.num_pkts_tx - num_pkts_tx[0] - stats_osmux.num_pkts_rx * flow[1].osmux_cfg.batch_size;
+		if (temp > 3 * flow[1].osmux_cfg.batch_size or temp < -3 * flow[1].osmux_cfg.batch_size) {
+			log("stats_rtp: ", stats_rtp);
+			log("stats_osmux: ", stats_osmux);
+			log("old_rtp_tx: ", num_pkts_tx[0]);
+			setverdict(fail, "number of packets not within normal parameters (" & int2str(temp) & ")");
+			mtc.stop;
+		}
+
+		temp := stats_osmux.num_pkts_tx - num_pkts_tx[1] - stats_rtp.num_pkts_rx / flow[1].osmux_cfg.batch_size;
+		if (temp > 3 or temp < -3) {
+			setverdict(fail, "number of packets not within normal parameters (" & int2str(temp) & ")");
+			mtc.stop;
+		}
+
+		f_rtpem_stats_err_check(stats_rtp);
+		f_osmuxem_stats_err_check(stats_osmux);
+
+		/* Tear down */
+		f_flow_delete(RTPEM[0]);
+		f_flow_delete_osmux(OsmuxEM, ep, call_id);
+		setverdict(pass);
+	}
+
+	/*  create one RTP and one OSmux emulations and pass data in both
+	    directions. Create CRCX with wildcard Osmux CID and set it later
+	    during MDCX. This is similar to how MSC sets up the call in AoIP. */
+	testcase TC_two_crcx_mdcx_and_rtp_osmux_wildcard() runs on dummy_CT {
+		f_two_crcx_mdcx_and_rtp_osmux(true);
+	}
+
+	/*  create one RTP and one OSmux emulations and pass data in both
+	    directions. Create CRCX with fixed Osmux CID and keep it during
+	    MDCX. This is similar to how BSC sets up the call in AoIP. */
+	testcase TC_two_crcx_mdcx_and_rtp_osmux_fixed() runs on dummy_CT {
+		f_two_crcx_mdcx_and_rtp_osmux(false);
+	}
+
 	function f_crcx_and_dlcx_ep_callid_connid(MgcpEndpoint ep, MgcpCallId call_id) runs on dummy_CT {
 		var template MgcpCommand cmd;
 		var MgcpResponse resp;
@@ -926,7 +1524,8 @@
 			portnr := omit
 		},
 		pt := pt,
-		codec := codec
+		codec := codec,
+		osmux_cid_sent := false
 	}
 
 	/* transmit RTP streams between two RTP Emulations back-to-back; expect no loss */
@@ -1482,6 +2081,16 @@
 		execute(TC_crcx_and_dlcx_ep_callid_connid_inval());
 		execute(TC_crcx_and_dlcx_retrans());
 
+		execute(TC_crcx_osmux_wildcard());
+		execute(TC_crcx_osmux_fixed());
+		execute(TC_crcx_osmux_fixed_twice());
+		execute(TC_one_crcx_receive_only_osmux());
+		execute(TC_one_crcx_loopback_osmux());
+		execute(TC_two_crcx_and_rtp_osmux());
+		execute(TC_two_crcx_and_rtp_osmux_bidir());
+		execute(TC_two_crcx_mdcx_and_rtp_osmux_wildcard());
+		execute(TC_two_crcx_mdcx_and_rtp_osmux_fixed());
+
 		execute(TC_crcx_dlcx_30ep());
 
 		execute(TC_rtpem_selftest());
diff --git a/mgw/expected-results.xml b/mgw/expected-results.xml
index 5c520c5..8975f78 100644
--- a/mgw/expected-results.xml
+++ b/mgw/expected-results.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0"?>
-<testsuite name='Titan' tests='35' failures='0' errors='0' skipped='1' inconc='0' time='MASKED'>
+<testsuite name='Titan' tests='44' failures='0' errors='0' skipped='1' inconc='0' time='MASKED'>
   <testcase classname='MGCP_Test' name='TC_selftest' time='MASKED'>
     <skipped>no verdict</skipped>
   </testcase>
@@ -26,6 +26,15 @@
   <testcase classname='MGCP_Test' name='TC_crcx_and_dlcx_ep_callid_inval' time='MASKED'/>
   <testcase classname='MGCP_Test' name='TC_crcx_and_dlcx_ep_callid_connid_inval' time='MASKED'/>
   <testcase classname='MGCP_Test' name='TC_crcx_and_dlcx_retrans' time='MASKED'/>
+  <testcase classname='MGCP_Test' name='TC_crcx_osmux_wildcard' time='MASKED'/>
+  <testcase classname='MGCP_Test' name='TC_crcx_osmux_fixed' time='MASKED'/>
+  <testcase classname='MGCP_Test' name='TC_crcx_osmux_fixed_twice' time='MASKED'/>
+  <testcase classname='MGCP_Test' name='TC_one_crcx_receive_only_osmux' time='MASKED'/>
+  <testcase classname='MGCP_Test' name='TC_one_crcx_loopback_osmux' time='MASKED'/>
+  <testcase classname='MGCP_Test' name='TC_two_crcx_and_rtp_osmux' time='MASKED'/>
+  <testcase classname='MGCP_Test' name='TC_two_crcx_and_rtp_osmux_bidir' time='MASKED'/>
+  <testcase classname='MGCP_Test' name='TC_two_crcx_mdcx_and_rtp_osmux_wildcard' time='MASKED'/>
+  <testcase classname='MGCP_Test' name='TC_two_crcx_mdcx_and_rtp_osmux_fixed' time='MASKED'/>
   <testcase classname='MGCP_Test' name='TC_crcx_dlcx_30ep' time='MASKED'/>
   <testcase classname='MGCP_Test' name='TC_rtpem_selftest' time='MASKED'/>
   <testcase classname='MGCP_Test' name='TC_one_crcx_receive_only_rtp' time='MASKED'/>
diff --git a/mgw/gen_links.sh b/mgw/gen_links.sh
index 632f2e3..f919637 100755
--- a/mgw/gen_links.sh
+++ b/mgw/gen_links.sh
@@ -41,6 +41,7 @@
 FILES="Misc_Helpers.ttcn General_Types.ttcn Osmocom_Types.ttcn MGCP_Types.ttcn MGCP_Templates.ttcn MGCP_CodecPort.ttcn
 MGCP_CodecPort_CtrlFunct.ttcn MGCP_CodecPort_CtrlFunctDef.cc "
 FILES+="RTP_CodecPort.ttcn RTP_Emulation.ttcn IuUP_Types.ttcn IuUP_Emulation.ttcn IuUP_EncDec.cc "
+FILES+="OSMUX_CodecPort.ttcn OSMUX_Emulation.ttcn OSMUX_Types.ttcn OSMUX_CodecPort_CtrlFunct.ttcn OSMUX_CodecPort_CtrlFunctDef.cc "
 FILES+="Native_Functions.ttcn Native_FunctionDefs.cc IPCP_Types.ttcn "
 FILES+="Osmocom_VTY_Functions.ttcn "
 gen_links $DIR $FILES
diff --git a/mgw/regen_makefile.sh b/mgw/regen_makefile.sh
index 64a4fc5..4662933 100755
--- a/mgw/regen_makefile.sh
+++ b/mgw/regen_makefile.sh
@@ -1,5 +1,5 @@
 #!/bin/sh
 
-FILES="*.ttcn SDP_EncDec.cc *.c MGCP_CodecPort_CtrlFunctDef.cc IPL4asp_PT.cc IPL4asp_discovery.cc TCCConversion.cc TCCInterface.cc RTP_EncDec.cc RTP_CodecPort_CtrlFunctDef.cc IuUP_EncDec.cc Native_FunctionDefs.cc TELNETasp_PT.cc IP_EncDec.cc "
+FILES="*.ttcn SDP_EncDec.cc *.c MGCP_CodecPort_CtrlFunctDef.cc IPL4asp_PT.cc IPL4asp_discovery.cc TCCConversion.cc TCCInterface.cc RTP_EncDec.cc RTP_CodecPort_CtrlFunctDef.cc OSMUX_CodecPort_CtrlFunctDef.cc IuUP_EncDec.cc Native_FunctionDefs.cc TELNETasp_PT.cc IP_EncDec.cc "
 
 ../regen-makefile.sh MGCP_Test.ttcn $FILES