diff --git a/stp/STP_Tests.ttcn b/stp/STP_Tests.ttcn
new file mode 100644
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--- /dev/null
+++ b/stp/STP_Tests.ttcn
@@ -0,0 +1,249 @@
+module STP_Tests {
+
+/* Osmocom STP test suite in in TTCN-3
+ * (C) 2019 Harald Welte <laforge@gnumonks.org>
+ * All rights reserved.
+ *
+ * Released under the terms of GNU General Public License, Version 2 or
+ * (at your option) any later version.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+import from General_Types all;
+import from Osmocom_Types all;
+import from IPL4asp_Types all;
+
+import from Osmocom_VTY_Functions all;
+
+import from M3UA_Types all;
+import from M3UA_Templates all;
+import from M3UA_CodecPort all;
+import from M3UA_CodecPort_CtrlFunct all;
+
+import from M3UA_Emulation all;
+import from MTP3asp_Types all;
+import from MTP3asp_PortType all;
+
+import from SCCP_Types all;
+import from SCCP_Templates all;
+import from SCCPasp_Types all;
+import from SCCP_Emulation all;
+
+import from IPA_Emulation all;
+
+import from STP_Tests_Common all;
+import from STP_Tests_IPA all;
+import from STP_Tests_M3UA all;
+
+
+type component IPA_M3UA_CT extends RAW_M3UA_CT, IPA_CT {
+};
+
+const OCT1 c_M3UA_SI_SCCP := '03'O;
+
+
+/* copy+pasted from SCCP_Emulation.ttcn, where for some reason it is marked as "runs on SCCP_CT"
+ * without depending on anything of that component */
+  function ConvertASPAddressToEncodedAddress_itu( in SCCP_PAR_Address pl_ASPAddress)
+    return SCCP_param_CPartyAddressEnc
+  {
+
+    var SCCP_param_CPartyAddress_itu vl_PDUAddress; //structured fit to encoding
+    var SCCP_param_CPartyAddressEnc vl_PDUAddressEncoded;
+
+    vl_PDUAddress.addressIndicator.pointCodeIndic:=
+      pl_ASPAddress.addressIndicator.pointCodeIndic;
+
+    vl_PDUAddress.addressIndicator.ssnIndicator:=
+      pl_ASPAddress.addressIndicator.ssnIndicator;
+
+    vl_PDUAddress.addressIndicator.globalTitleIndic:=
+     pl_ASPAddress.addressIndicator.globalTitleIndic;
+
+    vl_PDUAddress.addressIndicator.routingIndicator:=
+      pl_ASPAddress.addressIndicator.routingIndicator;
+
+    vl_PDUAddress.addressIndicator.reserved:='0'B;
+    // if (ischosen(pl_ASPAddress.signPointCode) ) not used because it is mandatory field (???)
+
+    //----signPointCode handling
+    if ( ispresent( pl_ASPAddress.signPointCode )) {
+      vl_PDUAddress.signPointCode :=
+        '00'B&pl_ASPAddress.signPointCode;
+    } else {
+      vl_PDUAddress.signPointCode := omit;
+    };
+
+    //----subsystemNumber handling
+    if ( ispresent( pl_ASPAddress.subsystemNumber ) ){
+      vl_PDUAddress.subsystemNumber := pl_ASPAddress.subsystemNumber;
+    } else {
+      vl_PDUAddress.subsystemNumber :=omit;
+    };
+
+    // --- globalTitle handling--
+    if ( ispresent(pl_ASPAddress.globalTitle))
+    {//startif1
+
+      var SCCP_ASPfield_GlobalTitle tmpGT ;
+      tmpGT := pl_ASPAddress.globalTitle;
+
+      if (ischosen(tmpGT.gti0001))
+      {
+        vl_PDUAddress.globalTitle.gti0001.natureOfAddress:=tmpGT.gti0001.natureOfAddress;
+        vl_PDUAddress.globalTitle.gti0001.oddeven:=tmpGT.gti0001.oddeven;
+        vl_PDUAddress.globalTitle.gti0001.globalTitleAddress:=tmpGT.gti0001.globalTitleAddress;
+      }
+      else if (ischosen(tmpGT.gti0010))
+      {
+        vl_PDUAddress.globalTitle.gti0010.translationType:=tmpGT.gti0010.translationType;
+        vl_PDUAddress.globalTitle.gti0010.globalTitleAddress:=tmpGT.gti0010.globalTitleAddress;
+      }
+      else if (ischosen(tmpGT.gti0011))
+      {
+        vl_PDUAddress.globalTitle.gti0011.translationType:=tmpGT.gti0011.translationType;
+        vl_PDUAddress.globalTitle.gti0011.encodingScheme:=tmpGT.gti0011.encodingScheme;
+        vl_PDUAddress.globalTitle.gti0011.numberingPlan:=tmpGT.gti0011.numberingPlan;
+        vl_PDUAddress.globalTitle.gti0011.globalTitleAddress:=tmpGT.gti0011.globalTitleAddress;
+      }
+      else if (ischosen(tmpGT.gti0100))
+      {
+        vl_PDUAddress.globalTitle.gti0100.translationType:=tmpGT.gti0100.translationType;
+        vl_PDUAddress.globalTitle.gti0100.encodingScheme:=tmpGT.gti0100.encodingScheme;
+        vl_PDUAddress.globalTitle.gti0100.numberingPlan:=tmpGT.gti0100.numberingPlan;
+        vl_PDUAddress.globalTitle.gti0100.natureOfAddress:=tmpGT.gti0100.natureOfAddress;
+        vl_PDUAddress.globalTitle.gti0100.reserved:='0'B;
+        vl_PDUAddress.globalTitle.gti0100.globalTitleAddress:=tmpGT.gti0100.globalTitleAddress;
+      }
+    }
+    else
+    {
+        vl_PDUAddress.globalTitle := omit;
+    };
+
+    vl_PDUAddressEncoded.addr:= enc_PDU_SCCP_Address_itu( vl_PDUAddress);
+    vl_PDUAddressEncoded.paramLength:= lengthof(vl_PDUAddressEncoded.addr);
+
+    return vl_PDUAddressEncoded;
+
+  } //ConvertASPAddressToEncodedAddress_itu
+
+template (value) PDU_SCCP ts_SCCP_UDT(SCCP_PAR_Address called, SCCP_PAR_Address calling,
+					template (value) octetstring data,
+					template (value) BIT4 msg_hdl := '0000'B) := {
+	unitdata := {
+		messageType := udt,
+		protClass := {'0000'B, msg_hdl},
+		pointer1 := 0,
+		pointer2 := 0,
+		pointer3 := 0,
+		calledPAddress := ConvertASPAddressToEncodedAddress_itu(called),
+		callingPAddress := ConvertASPAddressToEncodedAddress_itu(calling),
+		data := {
+			paramLength := 0,
+			data := data
+		}
+	}
+}
+
+/* Test routing of SCCP between an M3UA and an IPA ASP */
+testcase TC_m3ua_to_ipa() runs on IPA_M3UA_CT {
+	var OCT4 rctx_sender := int2oct(1023, 4);
+	var OCT4 pc_sender := int2oct(23, 4);
+	var OCT4 pc_receiver := int2oct(5, 4);
+
+	f_init_m3ua();
+	f_init_ipa();
+
+	f_M3UA_asp_up_act(0, omit, omit); // TODO: rctx
+
+	/* send a well-formed, encoded SCCP message via M3UA */
+	var octetstring data := f_rnd_octstring(f_rnd_int(100));
+	var SCCP_PAR_Address called := valueof(ts_SccpAddr_GT('1234'H));
+	var SCCP_PAR_Address calling := valueof(ts_SccpAddr_GT('5678'H));
+	var PDU_SCCP sccp := valueof(ts_SCCP_UDT(called, calling, data));
+	var octetstring sccp_enc := enc_PDU_SCCP(sccp);
+	var template (value) M3UA_Protocol_Data tx_pd;
+	tx_pd := ts_M3UA_protocol_data(pc_sender, pc_receiver, c_M3UA_SI_SCCP, '00'O, '00'O, '00'O, sccp_enc);
+	f_M3UA_send(0, ts_M3UA_DATA(rctx_sender, tx_pd), 1);
+
+	/* expect to receive it via IPA */
+	f_IPA_exp(0, sccp_enc);
+}
+
+/* test routing an SCCP message from IPA ASP to M3UA ASP */
+testcase TC_ipa_to_m3ua() runs on IPA_M3UA_CT {
+	var OCT4 pc_sender := int2oct(5, 4);
+	var OCT4 rctx_receiver := int2oct(1023, 4);
+	var OCT4 pc_receiver := int2oct(23, 4);
+
+	f_init_common();
+	f_vty_config2(VTY, {"cs7 instance 0", "as mahlzeit ipa"},
+		      "point-code override patch-sccp disabled");
+
+	f_init_m3ua();
+	f_init_ipa();
+
+	f_M3UA_asp_up_act(0, omit, omit); // TODO: rctx
+
+	/* send a well-formed, encoded SCCP message via IPA */
+	var octetstring data := f_rnd_octstring(f_rnd_int(100));
+	var SCCP_PAR_Address called := valueof(ts_SccpAddr_GT('1234'H));
+	var SCCP_PAR_Address calling := valueof(ts_SccpAddr_GT('5678'H));
+	var PDU_SCCP sccp := valueof(ts_SCCP_UDT(called, calling, data));
+	var octetstring sccp_enc := enc_PDU_SCCP(sccp);
+	f_IPA_send(0, sccp_enc);
+
+	/* expect to receive it via M3UA */
+	var template (present) M3UA_Protocol_Data rx_pd;
+	rx_pd := tr_M3UA_protocol_data(pc_sender, pc_receiver, c_M3UA_SI_SCCP, '00'O, '00'O, '00'O, sccp_enc);
+	f_M3UA_exp(0, tr_M3UA_DATA(rctx_receiver, rx_pd));
+}
+
+/* test routing an SCCP message from IPA ASP to M3UA ASP while patching PC into SCCP addresses */
+testcase TC_ipa_to_m3ua_patch_sccp() runs on IPA_M3UA_CT {
+	var OCT4 pc_sender := int2oct(5, 4);
+	var OCT4 rctx_receiver := int2oct(1023, 4);
+	var OCT4 pc_receiver := int2oct(23, 4);
+
+	f_init_common();
+	f_vty_config2(VTY, {"cs7 instance 0", "as mahlzeit ipa"},
+			"point-code override patch-sccp both");
+
+	f_init_m3ua();
+	f_init_ipa();
+
+	f_M3UA_asp_up_act(0, omit, omit); // TODO: rctx
+
+	/* send a well-formed, encoded SCCP message via IPA */
+	var octetstring data := f_rnd_octstring(f_rnd_int(100));
+	var SCCP_PAR_Address called := valueof(ts_SccpAddr_GT('1234'H));
+	var SCCP_PAR_Address calling := valueof(ts_SccpAddr_GT('5678'H));
+	var PDU_SCCP sccp := valueof(ts_SCCP_UDT(called, calling, data));
+	f_IPA_send(0, enc_PDU_SCCP(sccp));
+
+	/* patch point codes into addresses */
+	called := valueof(ts_SccpAddr_PC_GT(oct2int(pc_receiver), '83'O, "mtp3_itu", '1234'H));
+	calling := valueof(ts_SccpAddr_PC_GT(oct2int(pc_sender), '83'O, "mtp3_itu", '5678'H));
+	var PDU_SCCP sccp_exp := valueof(ts_SCCP_UDT(called, calling, data));
+
+	/* expect to receive it via M3UA */
+	var template (present) M3UA_Protocol_Data rx_pd;
+	rx_pd := tr_M3UA_protocol_data(pc_sender, pc_receiver, c_M3UA_SI_SCCP, '00'O, '00'O, '00'O,
+					enc_PDU_SCCP(sccp_exp));
+	f_M3UA_exp(0, tr_M3UA_DATA(rctx_receiver, rx_pd));
+}
+
+
+
+control {
+	/* M3UA <-> IPA Tests */
+	execute( TC_m3ua_to_ipa() );
+	execute( TC_ipa_to_m3ua() );
+	execute( TC_ipa_to_m3ua_patch_sccp() );
+}
+
+
+
+}