diff --git a/stp/STP_Tests_M3UA.ttcn b/stp/STP_Tests_M3UA.ttcn
index 3415e52..5c15c6f 100644
--- a/stp/STP_Tests_M3UA.ttcn
+++ b/stp/STP_Tests_M3UA.ttcn
@@ -36,14 +36,20 @@
 
 modulepar {
 	integer mp_stp_m3ua_port := 2905;
+	integer mp_stp_m3ua_clnt_port := 2906;
 	integer mp_local_m3ua_port := 9999;
 }
 
-private const integer NR_M3UA := 3;
+private const integer NR_M3UA := 3;	/* number of M3UA clients in ATS */
+private const integer NR_M3UA_SRV := 1;	/* number of M3UA servres in ATS */
+
+private function M3UA_SRV(integer idx) return integer {
+	return NR_M3UA+idx;
+}
 
 type component RAW_M3UA_CT extends Test_CT {
-	port M3UA_CODEC_PT M3UA[NR_M3UA];
-	var integer g_m3ua_conn_id[NR_M3UA];
+	port M3UA_CODEC_PT M3UA[NR_M3UA+NR_M3UA_SRV];
+	var integer g_m3ua_conn_id[NR_M3UA+NR_M3UA_SRV];
 }
 
 private template PortEvent tr_SctpAssocChange := {
@@ -56,6 +62,10 @@
 		sctpPeerAddrChange := ?
 	}
 }
+private template PortEvent tr_SctpConnOpened := {
+	connOpened := ?
+}
+
 
 private altstep as_m3ua_sctp() runs on RAW_M3UA_CT {
 	[] any from M3UA.receive(tr_SctpAssocChange) { repeat; }
@@ -93,6 +103,16 @@
 	g_m3ua_conn_id[i] := res.connId;
 }
 
+friend function f_M3UA_listen(integer i) runs on RAW_M3UA_CT {
+	var Result res;
+	res := M3UA_CodecPort_CtrlFunct.f_IPL4_listen(M3UA[i], mp_local_ip, mp_local_m3ua_port+i,
+							{sctp:=valueof(ts_SCTP)});
+	if (not ispresent(res.connId)) {
+		setverdict(fail, "Could not bind M3UA socket, check your configuration");
+	mtc.stop;
+	}
+}
+
 friend function f_init_m3ua() runs on RAW_M3UA_CT {
 	var integer i;
 
@@ -106,6 +126,26 @@
 	}
 }
 
+friend function f_init_m3ua_srv() runs on RAW_M3UA_CT {
+	var integer i;
+	var PortEvent sctp_evt;
+
+	for (i := NR_M3UA; i < NR_M3UA+NR_M3UA_SRV; i:=i+1) {
+		map(self:M3UA[i], system:M3UA_CODEC_PT);
+		/* bind+ listen */
+		f_M3UA_listen(i);
+		/* wait for accept() */
+		M3UA[i].receive(tr_SctpConnOpened) -> value sctp_evt {
+			g_m3ua_conn_id[i] := sctp_evt.connOpened.connId;
+		}
+	}
+}
+
+
+/***********************************************************************
+ * Test the STP in M3UA SG role (we are ASP)
+ ***********************************************************************/
+
 /* perform an outbound ASP-UP procedure */
 friend function f_M3UA_asp_up(integer idx, template (omit) OCT4 aspid := omit) runs on RAW_M3UA_CT {
 	f_M3UA_send(idx, ts_M3UA_ASPUP(aspid));
@@ -417,6 +457,97 @@
 	/* FIXME: we now may have changed the state on the STP side! */
 }
 
+/***********************************************************************
+ * Test the STP in M3UA ASP role (we are SG)
+ ***********************************************************************/
+
+/* expect/perform an inbound ASP-UP procedure */
+friend function f_M3UA_CLNT_asp_up(integer idx, template OCT4 aspid := omit) runs on RAW_M3UA_CT {
+	f_M3UA_exp(idx, tr_M3UA_ASPUP(aspid));
+	f_M3UA_send(idx, ts_M3UA_ASPUP_ACK);
+}
+
+/* expect/perform an inbound ASP-ACTIVATE procedure */
+friend function f_M3UA_CLNT_asp_act(integer idx, template M3UA_Traffic_Mode_Type tmt := omit,
+				template (omit) OCT4 rctx := omit) runs on RAW_M3UA_CT {
+	f_M3UA_exp(idx, tr_M3UA_ASPAC(tmt, rctx));
+	f_M3UA_send(idx, ts_M3UA_ASPAC_ACK(tmt, rctx));
+}
+
+/* expect/perform inbound ASP-UP and ASP-ACT, optionally send interemittent NOTIFY */
+friend function f_M3UA_CLNT_asp_up_act(integer idx, template M3UA_Traffic_Mode_Type tmt := omit,
+				   template OCT4 rctx := omit,
+				   template (omit) OCT2 ntfy_after_up := c_M3UA_ST_I_AS_INACTIVE,
+				   template (omit) OCT2 ntfy_after_act := c_M3UA_ST_I_AS_ACTIVE)
+runs on RAW_M3UA_CT {
+	f_M3UA_CLNT_asp_up(idx, omit);
+	if (not istemplatekind(ntfy_after_up, "omit")) {
+		f_M3UA_send(idx, ts_M3UA_NOTIFY(c_M3UA_ST_T_STATE_CHG, ntfy_after_up, rctx));
+	}
+	f_M3UA_CLNT_asp_act(idx, tmt, rctx);
+	if (not istemplatekind(ntfy_after_act, "omit")) {
+		f_M3UA_send(idx, ts_M3UA_NOTIFY(c_M3UA_ST_T_STATE_CHG, ntfy_after_act, rctx));
+	}
+}
+
+
+/* Expect inbound connection from ASP/SCTP-client, followed by ASP-UP */
+testcase TC_clnt_connect_asp_up() runs on RAW_M3UA_CT {
+	f_init_m3ua();
+	f_init_m3ua_srv();
+
+	f_M3UA_CLNT_asp_up(M3UA_SRV(0));
+}
+
+/* Expect inbound connection from ASP/SCTP-client, followed by ASP-UP + ASP-ACT */
+testcase TC_clnt_asp_act() runs on RAW_M3UA_CT {
+	f_init_m3ua();
+	f_init_m3ua_srv();
+
+	f_M3UA_CLNT_asp_up_act(M3UA_SRV(0));
+}
+
+/* Test traffic being routed through "server" side STP (M3UA SG), coming back in "client"
+ * side STP (M3UA ASP) */
+testcase TC_clnt_sg_to_asp() runs on RAW_M3UA_CT {
+	var OCT4 rctx_sender := int2oct(1023, 4);
+	var OCT4 pc_sender := int2oct(23, 4);
+	var OCT4 rctx_receiver := int2oct(1055, 4);
+	var OCT4 pc_receiver := int2oct(55, 4);
+
+	f_init_m3ua();
+	f_M3UA_asp_up_act(0);
+
+	f_init_m3ua_srv();
+	f_M3UA_CLNT_asp_up_act(M3UA_SRV(0));
+
+	f_sleep(1.0);
+
+	/* verify traffic is routed from sender to [sole] receiver */
+	f_test_traffic(0, rctx_sender, pc_sender, M3UA_SRV(0), rctx_receiver, pc_receiver);
+}
+
+/* Test traffic being routed through "client" side STP (M3UA ASP), coming back in "server"
+ * side STP (M3UA SG) */
+testcase TC_clnt_asp_to_sg() runs on RAW_M3UA_CT {
+	var OCT4 rctx_sender := int2oct(1055, 4);
+	var OCT4 pc_sender := int2oct(55, 4);
+	var OCT4 rctx_receiver := int2oct(1023, 4);
+	var OCT4 pc_receiver := int2oct(23, 4);
+
+	f_init_m3ua();
+	f_M3UA_asp_up_act(0);
+
+	f_init_m3ua_srv();
+	f_M3UA_CLNT_asp_up_act(M3UA_SRV(0));
+
+	f_sleep(1.0);
+
+	/* verify traffic is routed from sender to [sole] receiver */
+	f_test_traffic(M3UA_SRV(0), rctx_sender, pc_sender, 0, rctx_receiver, pc_receiver);
+}
+
+
 
 control {
 	/* M3UA Tests */
@@ -442,6 +573,12 @@
 	/* TODO: test RKM with unsupported routing keys: NA, SI, OPC */
 	/* TODO: register/unregister multiple routing contexts in one message; including mixed
 	         success/failure situations */
+
+	/* Test STP as SCTP client + M3UA ASP role */
+	execute( TC_clnt_connect_asp_up() );
+	execute( TC_clnt_asp_act() );
+	execute( TC_clnt_sg_to_asp() );
+	execute( TC_clnt_asp_to_sg() );
 }
 
 
diff --git a/stp/osmo-stp.cfg b/stp/osmo-stp.cfg
index d5eccba..d8630d2 100644
--- a/stp/osmo-stp.cfg
+++ b/stp/osmo-stp.cfg
@@ -45,6 +45,11 @@
  asp asp-receiver1 10001 2905 m3ua
   local-ip 127.0.0.1
   remote-ip 127.0.0.1
+ asp asp-client0 10002 2906 m3ua
+  local-ip 127.0.0.1
+  remote-ip 127.0.0.1
+  sctp-role client
+  role asp
  as as-sender m3ua
   asp asp-sender
   routing-key 1023 23
@@ -54,9 +59,13 @@
  as mahlzeit ipa
   routing-key 0 5
   point-code override dpc 23
+ as as-client m3ua
+  routing-key 1055 55
+  asp asp-client0
  route-table system
   update route 23 16777215 linkset as-sender
   update route 42 16777215 linkset as-receiver
+  update route 55 16777215 linkset as-client
  listen m3ua 2905
   accept-asp-connections dynamic-permitted
  listen ipa 5000