diff --git a/asterisk/IMS_ConnectionHandler.ttcn b/asterisk/IMS_ConnectionHandler.ttcn
index a55935a..a253c9f 100644
--- a/asterisk/IMS_ConnectionHandler.ttcn
+++ b/asterisk/IMS_ConnectionHandler.ttcn
@@ -388,8 +388,8 @@
 	var template (present) PDU_SIP_Request exp_req :=
 		tr_SIP_REGISTER(g_pars.registrar_sip_req_uri,
 				?,
-				tr_SipAddr(),
-				tr_SipAddr(),
+				tr_From(),
+				tr_To(),
 				tr_Via_from(?),
 				require := tr_Require(superset("sec-agree")),
 				security_client := tr_Security_client(superset(tr_Security_mechanism("ipsec-3gpp",
@@ -402,8 +402,8 @@
 		var Via via;
 		var CallidString sip_call_id;
 		var Contact contact;
-		var template (value) SipAddr from_addr;
-		var template (value) SipAddr to_addr;
+		var template (value) From from_addr;
+		var template (value) To to_addr;
 		var template (value) CommaParam_List digestCln ;
 		var template (value) WwwAuthenticate wwwAuthenticate;
 		var template (value) P_Associated_Uri p_associated_uri := ts_P_Associated_Uri({});
@@ -418,10 +418,8 @@
 		sip_call_id := g_rx_sip_req.msgHeader.callId.callid;
 		via := g_rx_sip_req.msgHeader.via;
 		via.viaBody[0].viaParams := f_sip_param_set(via.viaBody[0].viaParams, "rport", "1234"); /* TODO: set remote src port of the REGISTER */
-		from_addr := ts_SipAddr_from_Addr_Union(g_rx_sip_req.msgHeader.fromField.addressField,
-							g_rx_sip_req.msgHeader.fromField.fromParams);
-		to_addr := ts_SipAddr_from_Addr_Union(g_rx_sip_req.msgHeader.toField.addressField,
-						      g_rx_sip_req.msgHeader.toField.toParams);
+		from_addr := g_rx_sip_req.msgHeader.fromField;
+		to_addr := g_rx_sip_req.msgHeader.toField;
 		sip_seq_nr := g_rx_sip_req.msgHeader.cSeq.seqNumber;
 
 		contact := g_rx_sip_req.msgHeader.contact;
@@ -455,7 +453,7 @@
 		f_ims_parse_security_client(g_rx_sip_req.msgHeader.security_client);
 		f_ims_setup_ipsec();
 
-		to_addr.params := f_sip_param_set(to_addr.params, "tag", f_sip_rand_tag());
+		to_addr.toParams := f_sip_param_set(to_addr.toParams, "tag", f_sip_rand_tag());
 
 		digestCln := {
 			ts_Param("realm", f_sip_str_quote(g_pars.realm)),
@@ -512,18 +510,16 @@
 		exp_req :=
 		tr_SIP_REGISTER(g_pars.registrar_sip_req_uri,
 				?,
-				tr_SipAddr(),
-				tr_SipAddr(),
+				tr_From(),
+				tr_To(),
 				tr_Via_from(?),
 				authorization := authorization);
 		SIP.receive(exp_req) -> value g_rx_sip_req;
 
 		sip_call_id := g_rx_sip_req.msgHeader.callId.callid;
 		via := g_rx_sip_req.msgHeader.via;
-		from_addr := ts_SipAddr_from_Addr_Union(g_rx_sip_req.msgHeader.fromField.addressField,
-							g_rx_sip_req.msgHeader.fromField.fromParams);
-		to_addr := ts_SipAddr_from_Addr_Union(g_rx_sip_req.msgHeader.toField.addressField,
-						      g_rx_sip_req.msgHeader.toField.toParams);
+		from_addr := g_rx_sip_req.msgHeader.fromField;
+		to_addr := g_rx_sip_req.msgHeader.toField;
 		sip_seq_nr := g_rx_sip_req.msgHeader.cSeq.seqNumber;
 
 		/* Tx 100 Trying */
@@ -552,7 +548,7 @@
 			});
 
 		/* Tx 200 OK */
-		to_addr.params := f_sip_param_set(to_addr.params, "tag", f_sip_rand_tag());
+		to_addr.toParams := f_sip_param_set(to_addr.toParams, "tag", f_sip_rand_tag());
 		tx_resp := ts_SIP_Response(sip_call_id,
 			from_addr,
 			to_addr,
diff --git a/asterisk/SIP_ConnectionHandler.ttcn b/asterisk/SIP_ConnectionHandler.ttcn
index 9c7cca5..41a29e4 100644
--- a/asterisk/SIP_ConnectionHandler.ttcn
+++ b/asterisk/SIP_ConnectionHandler.ttcn
@@ -80,8 +80,8 @@
 	SipAddr calling optional,
 	SipAddr called optional,
 
-	SipAddr from_addr optional,
-	SipAddr to_addr optional,
+	From from_addr optional,
+	To to_addr optional,
 
 	CallidString sip_call_id,
 	integer sip_seq_nr,
@@ -263,7 +263,9 @@
 	var template (present) PDU_SIP_Response exp;
 	var Authorization authorization;
 	var Via via := g_pars.local_via;
-	var SipAddr from_sipaddr := g_pars.registrar_sip_record;
+	var From from_addr := valueof(ts_From(g_pars.registrar_sip_record.addr, g_pars.registrar_sip_record.params));
+	var To to_addr := valueof(ts_To(g_pars.registrar_sip_record.addr, g_pars.registrar_sip_record.params));
+	var template (present) To to_addr_exp := tr_To(tr_Addr_Union_from_val(to_addr.addressField), *);
 	var charstring branch_value;
 
 	branch_value := f_sip_gen_branch(f_sip_SipAddr_to_str(g_pars.registrar_sip_record),
@@ -272,11 +274,11 @@
 					 g_pars.registrar_sip_seq_nr);
 
 	via.viaBody[0].viaParams := f_sip_param_set(via.viaBody[0].viaParams, "branch", branch_value);
-	from_sipaddr.params := f_sip_param_set(from_sipaddr.params, "tag", f_sip_rand_tag());
+	from_addr.fromParams := f_sip_param_set(from_addr.fromParams, "tag", f_sip_rand_tag());
 	SIP.send(ts_SIP_REGISTER(g_pars.registrar_sip_req_uri,
 				 g_pars.registrar_sip_call_id,
-				 from_sipaddr,
-				 g_pars.registrar_sip_record,
+				 from_addr,
+				 to_addr,
 				 via,
 				 g_pars.registrar_sip_seq_nr,
 				 g_pars.local_contact,
@@ -284,8 +286,8 @@
 
 	exp := tr_SIP_Response_Unauthorized(
 			g_pars.registrar_sip_call_id,
-			from_sipaddr,
-			f_tr_To_response(g_pars.registrar_sip_record),
+			from_addr,
+			to_addr_exp,
 			f_tr_Via_response(via),
 			*,
 			tr_WwwAuthenticate({tr_Challenge_digestCln(?)}),
@@ -308,8 +310,8 @@
 
 	SIP.send(ts_SIP_REGISTER(g_pars.registrar_sip_req_uri,
 				g_pars.registrar_sip_call_id,
-				from_sipaddr,
-				g_pars.registrar_sip_record,
+				from_addr,
+				to_addr,
 				via,
 				g_pars.registrar_sip_seq_nr,
 				g_pars.local_contact,
@@ -319,8 +321,8 @@
 	/* Wait for OK answer */
 	exp := tr_SIP_Response(
 			g_pars.registrar_sip_call_id,
-			from_sipaddr,
-			f_tr_To_response(g_pars.registrar_sip_record),
+			from_addr,
+			to_addr_exp,
 			f_tr_Via_response(via),
 			*,
 			"REGISTER", 200,
@@ -336,17 +338,21 @@
 {
 	var template (value) PDU_SIP_Request req;
 	var template (present) PDU_SIP_Response exp;
+	var template (present) From from_addr_exp;
+	var template (present) To to_addr_exp;
 	var Via via;
 	var charstring tx_sdp := f_gen_sdp();
 	var default d_trying, d_ringing;
 	var charstring branch_value;
 
 	/* RFC 3261 8.1.1.3 From */
-	g_pars.cp.from_addr := g_pars.cp.calling;
-	g_pars.cp.from_addr.params := f_sip_param_set(g_pars.cp.from_addr.params, "tag", f_sip_rand_tag());
-	g_pars.cp.to_addr := g_pars.cp.called;
-	branch_value := f_sip_gen_branch(f_sip_SipAddr_to_str(g_pars.cp.from_addr),
-					 f_sip_SipAddr_to_str(valueof(g_pars.cp.to_addr)),
+	g_pars.cp.from_addr := valueof(ts_From(g_pars.cp.calling.addr, g_pars.cp.calling.params));
+	g_pars.cp.from_addr.fromParams := f_sip_param_set(g_pars.cp.from_addr.fromParams, "tag", f_sip_rand_tag());
+	g_pars.cp.to_addr := valueof(ts_To(g_pars.cp.called.addr, g_pars.cp.called.params));
+	from_addr_exp := tr_From(tr_Addr_Union_from_val(g_pars.cp.from_addr.addressField), *);
+	to_addr_exp := tr_To(tr_Addr_Union_from_val(g_pars.cp.to_addr.addressField), *);
+	branch_value := f_sip_gen_branch(f_sip_Addr_Union_to_str(g_pars.cp.from_addr.addressField),
+					 f_sip_Addr_Union_to_str(valueof(g_pars.cp.to_addr.addressField)),
 					 g_pars.cp.sip_call_id,
 					 g_pars.cp.sip_seq_nr);
 	via := g_pars.local_via;
@@ -365,8 +371,8 @@
 	/* RFC 3261 22.2: */
 	exp := tr_SIP_Response_Unauthorized(
 			g_pars.cp.sip_call_id,
-			f_tr_From(g_pars.cp.from_addr),
-			f_tr_To_response(g_pars.cp.to_addr),
+			from_addr_exp,
+			to_addr_exp,
 			f_tr_Via_response(via),
 			*,
 			tr_WwwAuthenticate({tr_Challenge_digestCln(?)}),
@@ -385,16 +391,16 @@
 
 	/* Conditionally match and accept 100 Trying. */
 	exp := tr_SIP_Response_Trying(g_pars.cp.sip_call_id,
-			g_pars.cp.from_addr,
-			f_tr_To_response(g_pars.cp.to_addr),
+			from_addr_exp,
+			to_addr_exp,
 			f_tr_Via_response(via),
 			g_pars.cp.sip_seq_nr, "INVITE");
 	d_trying := activate(as_SIP_ignore_resp(exp));
 
 	/* Conditionally match and accept 180 Ringing */
 	exp := tr_SIP_Response_Ringing(g_pars.cp.sip_call_id,
-			g_pars.cp.from_addr,
-			f_tr_To_response(g_pars.cp.to_addr),
+			from_addr_exp,
+			to_addr_exp,
 			f_tr_Via_response(via),
 			g_pars.cp.sip_seq_nr, "INVITE");
 	d_ringing := activate(as_SIP_ignore_resp(exp));
@@ -402,8 +408,8 @@
 	/* Wait for OK answer */
 	exp := tr_SIP_Response(
 			g_pars.cp.sip_call_id,
-			g_pars.cp.from_addr,
-			f_tr_To_response(g_pars.cp.to_addr),
+			from_addr_exp,
+			to_addr_exp,
 			f_tr_Via_response(via),
 			*,
 			"INVITE", 200,
@@ -415,8 +421,7 @@
 	deactivate(d_ringing);
 
 	/* Update To with the tags received from peer: */
-	g_pars.cp.to_addr := valueof(ts_SipAddr_from_Addr_Union(g_rx_sip_resp.msgHeader.toField.addressField,
-								g_rx_sip_resp.msgHeader.toField.toParams));
+	g_pars.cp.to_addr := g_rx_sip_resp.msgHeader.toField;
 
 	/* Transmit ACK */
 	g_pars.cp.sip_seq_nr := g_pars.cp.sip_seq_nr + 1;
@@ -437,11 +442,9 @@
 
 	/* Obtain params: */
 	g_pars.cp.sip_call_id := rx_sip_req.msgHeader.callId.callid;
-	g_pars.cp.from_addr := valueof(ts_SipAddr_from_Addr_Union(rx_sip_req.msgHeader.fromField.addressField,
-								rx_sip_req.msgHeader.fromField.fromParams));
-	g_pars.cp.to_addr := valueof(ts_SipAddr_from_Addr_Union(rx_sip_req.msgHeader.toField.addressField,
-								rx_sip_req.msgHeader.toField.toParams));
-	g_pars.cp.to_addr.params := f_sip_param_set(g_pars.cp.to_addr.params, "tag", f_sip_rand_tag());
+	g_pars.cp.from_addr := rx_sip_req.msgHeader.fromField;
+	g_pars.cp.to_addr := rx_sip_req.msgHeader.toField;
+	g_pars.cp.to_addr.toParams := f_sip_param_set(g_pars.cp.to_addr.toParams, "tag", f_sip_rand_tag());
 	g_pars.cp.sip_seq_nr := rx_sip_req.msgHeader.cSeq.seqNumber;
 }
 
@@ -452,8 +455,8 @@
 	var template (present) PDU_SIP_Request exp_req :=
 		tr_SIP_INVITE(f_tr_SipUrl_opt_defport(g_pars.local_sip_url_ext),
 			      ?,
-			      f_tr_From(g_pars.cp.calling),
-			      g_pars.cp.called,
+			      tr_From(tr_Addr_Union_from_val(g_pars.cp.calling.addr), *),
+			      tr_To(tr_Addr_Union_from_val(g_pars.cp.called.addr), *),
 			      tr_Via_from(f_tr_HostPort(g_pars.remote_sip_host, g_pars.remote_sip_port)),
 			      ?, ?);
 	var charstring sip_expect_str := log2str(exp_req);
@@ -518,8 +521,8 @@
 	var template (present) PDU_SIP_Request exp_req :=
 		tr_SIP_INVITE(f_tr_SipUrl_opt_defport(g_pars.local_sip_url_ext),
 			      ?,
-			      f_tr_From(g_pars.cp.calling),
-			      g_pars.cp.called,
+			      tr_From(tr_Addr_Union_from_val(g_pars.cp.calling.addr), *),
+			      tr_To(tr_Addr_Union_from_val(g_pars.cp.called.addr), *),
 			      tr_Via_from(f_tr_HostPort(g_pars.remote_sip_host, g_pars.remote_sip_port)),
 			      ?, ?);
 	var charstring sip_expect_str := log2str(exp_req);
@@ -527,7 +530,7 @@
 	[] SIP.receive(exp_req) -> value g_rx_sip_req {
 		var template (value) PDU_SIP_Response tx_resp;
 		var Via via;
-		var template (present) SipAddr exp_to_addr;
+		var template (present) To exp_to_addr;
 		var charstring tx_sdp;
 
 		/* Obtain params: */
@@ -550,8 +553,7 @@
 		/* Wait for CANCEL */
 		/* Cancel may come even before we send Ringing, hence To's "tag"
 		 * may not be known by peer, so g_pars.to_addr can't be used here: */
-		exp_to_addr := ts_SipAddr_from_Addr_Union(g_rx_sip_req.msgHeader.toField.addressField,
-							  g_rx_sip_req.msgHeader.toField.toParams);
+		exp_to_addr := g_rx_sip_req.msgHeader.toField;
 		exp_req := tr_SIP_CANCEL(f_tr_SipUrl_opt_defport(g_pars.local_sip_url_ext),
 					 g_pars.cp.sip_call_id,
 					 g_pars.cp.from_addr,
@@ -636,8 +638,8 @@
 	var Via via;
 	var charstring branch_value;
 
-	branch_value := f_sip_gen_branch(f_sip_SipAddr_to_str(g_pars.cp.from_addr),
-					 f_sip_SipAddr_to_str(valueof(g_pars.cp.to_addr)),
+	branch_value := f_sip_gen_branch(f_sip_Addr_Union_to_str(g_pars.cp.from_addr.addressField),
+					 f_sip_Addr_Union_to_str(valueof(g_pars.cp.to_addr.addressField)),
 					 g_pars.cp.sip_call_id,
 					 g_pars.cp.sip_seq_nr);
 
@@ -657,7 +659,7 @@
 	exp_resp := tr_SIP_Response(
 			g_pars.cp.sip_call_id,
 			g_pars.cp.from_addr,
-			f_tr_To_response(g_pars.cp.to_addr),
+			tr_To(tr_Addr_Union_from_val(g_pars.cp.to_addr.addressField), *),
 			f_tr_Via_response(via),
 			*,
 			"BYE", 200,