diff --git a/asterisk/IMS_ConnectionHandler.ttcn b/asterisk/IMS_ConnectionHandler.ttcn
index 091f5da..a55935a 100644
--- a/asterisk/IMS_ConnectionHandler.ttcn
+++ b/asterisk/IMS_ConnectionHandler.ttcn
@@ -66,6 +66,7 @@
 	charstring user,
 	charstring display_name,
 	charstring password,
+	charstring msisdn,
 	/* Expected User-Location-Info in P-Access-Network-Info */
 	charstring uli_str,
 	octetstring rand,
@@ -150,6 +151,7 @@
 	user := user,
 	display_name := f_sip_str_quote(display_name),
 	password := password,
+	msisdn := "90828",
 	uli_str := "2380100010000101",
 	/* The Nonce field is the Base64 encoded version of the RAND value and concatenated with the AUTN: */
 	rand := '14987631f65f8e3788a0798b6ebcd08e'O,
@@ -404,6 +406,7 @@
 		var template (value) SipAddr 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({});
 		var template (value) Security_server security_server;
 		var template (value) Server server_name := ts_Server({c_sip_server_name});
 		var template (value) Require require := ts_Require({"sec-agree"});
@@ -487,6 +490,7 @@
 					wwwAuthenticate,
 					sip_seq_nr,
 					"REGISTER",
+					p_associated_uri := p_associated_uri,
 					security_server := security_server,
 					server := server_name,
 					supported := supported,
@@ -537,6 +541,16 @@
 		/* Validate P-Access-Network-Info: */
 		f_ims_validate_register_P_Access_Network_info(g_rx_sip_req, exp_present := true);
 
+		p_associated_uri := ts_P_Associated_Uri({
+				ts_P_Assoc_uri_spec(ts_NameAddr(ts_SipUrl(ts_HostPort(g_pars.realm),
+									  ts_UserInfo(g_pars.msisdn),
+									  scheme := "sip"))),
+				ts_P_Assoc_uri_spec(ts_NameAddr(ts_SipUrl(ts_HostPort(g_pars.msisdn),
+									  omit,
+									  scheme := "tel"))),
+				ts_P_Assoc_uri_spec(g_rx_sip_req.msgHeader.toField.addressField.nameAddr)
+			});
+
 		/* Tx 200 OK */
 		to_addr.params := f_sip_param_set(to_addr.params, "tag", f_sip_rand_tag());
 		tx_resp := ts_SIP_Response(sip_call_id,
@@ -546,6 +560,7 @@
 			sip_seq_nr,
 			"OK",
 			via,
+			p_associated_uri := p_associated_uri,
 			require := require,
 			server := server_name,
 			supported := supported,