diff --git a/bsc-nat/BSCNAT_Tests.ttcn b/bsc-nat/BSCNAT_Tests.ttcn
new file mode 100644
index 0000000..b6dca28
--- /dev/null
+++ b/bsc-nat/BSCNAT_Tests.ttcn
@@ -0,0 +1,149 @@
+module BSCNAT_Tests {
+
+import from Osmocom_Types all;
+
+import from IPL4asp_Types all;
+
+import from IPA_Emulation all;
+
+import from MTP3asp_Types all;
+
+import from SCCP_Types all;
+import from SCCPasp_Types all;
+import from SCCP_Emulation all;
+
+import from MSC_Simulation all;
+import from BSC_MS_Simulation all;
+
+const integer NUM_MSC := 1;
+const integer NUM_BSC := 1;
+
+type record BscState {
+	BSC_CT BSC,
+	MSC_SCCP_MTP3_parameters sccp_pars,
+	SCCP_PAR_Address sccp_addr_own,
+	SCCP_PAR_Address sccp_addr_peer
+}
+
+type record MscState {
+	MSC_CT MSC,
+	MSC_SCCP_MTP3_parameters sccp_pars,
+	SCCP_PAR_Address sccp_addr_own
+}
+
+type component test_CT {
+	var MscState msc[NUM_MSC];
+	var BscState bsc[NUM_BSC];
+
+	var boolean g_initialized := false;
+	var octetstring g_sio := '83'O;
+}
+
+modulepar {
+	PortNumber mp_bsc_port := 49999;
+	charstring mp_bsc_ip := "127.0.0.1";
+
+	PortNumber mp_msc_port := 5000;
+	charstring mp_msc_ip := "127.0.0.1";
+
+	PortNumber mp_nat_port := 5000;
+	charstring mp_nat_ip := "127.0.0.1";
+
+	charstring mp_sccp_service_type := "mtp3_itu";
+
+	integer mp_bsc_pc := 196;
+	integer mp_bsc_ssn := 254;
+
+	integer mp_msc_pc := 185;	/* 0.23.1 */
+	integer mp_msc_ssn := 254;
+}
+
+/* construct a SCCP_PAR_Address with just PC + SSN and no GT */
+template (value) SCCP_PAR_Address ts_SccpAddr_PC_SSN(integer pc, integer ssn) := {
+	addressIndicator := {
+		pointCodeIndic := '1'B,
+		ssnIndicator := '1'B,
+		globalTitleIndic := '0000'B,
+		routingIndicator := '1'B
+	},
+	signPointCode := SCCP_SPC_int2bit(pc, mp_sccp_service_type, '83'O),
+	//signPointCode := SCCP_SPC_int2bit(pc, mp_sccp_service_type, g_sio),
+	subsystemNumber := ssn,
+	globalTitle := omit
+}
+
+template MTP3_Field_sio ts_sio(octetstring sio_in) := {
+	ni := substr(oct2bit(sio_in),0,2),
+	prio := substr(oct2bit(sio_in),2,2),
+	si := substr(oct2bit(sio_in),4,4)
+}
+
+template MSC_SCCP_MTP3_parameters ts_SCCP_Pars(octetstring sio, integer opc, integer dpc,
+						integer local_ssn) := {
+	sio := ts_sio(sio),
+	opc := opc,
+	dpc := dpc,
+	sls := 0,
+	sccp_serviceType := mp_sccp_service_type,
+	ssn := local_ssn
+};
+
+function f_init_BscState(inout BscState bsc_st, integer opc, integer dpc, integer local_ssn, integer remote_ssn)
+runs on test_CT {
+	bsc_st.sccp_pars := valueof(ts_SCCP_Pars(g_sio, opc, dpc, local_ssn));
+	bsc_st.sccp_addr_own := valueof(ts_SccpAddr_PC_SSN(opc, local_ssn));
+	bsc_st.sccp_addr_peer := valueof(ts_SccpAddr_PC_SSN(dpc, remote_ssn));
+}
+
+function f_init_MscState(inout MscState msc_st, integer opc, integer dpc, integer local_ssn, integer remote_ssn)
+runs on test_CT {
+	msc_st.sccp_pars := valueof(ts_SCCP_Pars(g_sio, opc, dpc, local_ssn));
+	msc_st.sccp_addr_own := valueof(ts_SccpAddr_PC_SSN(opc, local_ssn));
+}
+
+function f_init() runs on test_CT {
+	var integer i;
+	var charstring id;
+
+	for (i := 0; i < NUM_MSC; i := i+1) {
+		f_init_MscState(msc[i], mp_msc_pc +i, mp_bsc_pc, mp_msc_ssn, mp_bsc_ssn);
+		msc[i].MSC := MSC_CT.create;
+		id := "MSC" & int2str(i);
+		msc[i].MSC.start(MSC_Simulation.main(mp_msc_ip, mp_msc_port + i, msc[i].sccp_pars, msc[i].sccp_addr_own, id));
+	}
+
+	for (i := 0; i < NUM_BSC; i := i+1) {
+		f_init_BscState(bsc[i], mp_bsc_pc +i, mp_msc_pc, mp_bsc_ssn, mp_msc_ssn);
+		bsc[i].BSC := BSC_CT.create;
+		id := "BSC" & int2str(i);
+		bsc[i].BSC.start(BSC_MS_Simulation.main(mp_nat_ip, mp_nat_port, mp_bsc_ip, mp_bsc_port+i,
+							bsc[i].sccp_pars, bsc[i].sccp_addr_own,
+							bsc[i].sccp_addr_peer, id));
+	}
+
+}
+
+testcase TC_recv_dump() runs on test_CT {
+	var integer i;
+	timer T := 30.0;
+
+	f_init();
+
+	alt {
+		/* wait for BSC to stop. The idea is that the BSC components terminate first */
+		[] bsc[0].BSC.done { }
+		[] T.timeout { setverdict(fail); }
+	}
+
+	all component.stop;
+	/* terminate the MSCs */
+	for (i := 0; i < NUM_MSC; i := i+1) {
+		msc[i].MSC.stop;
+	}
+}
+
+control {
+	execute( TC_recv_dump() );
+}
+
+}