diff --git a/asterisk/IMS_ConnectionHandler.ttcn b/asterisk/IMS_ConnectionHandler.ttcn
index 0d11922..091f5da 100644
--- a/asterisk/IMS_ConnectionHandler.ttcn
+++ b/asterisk/IMS_ConnectionHandler.ttcn
@@ -503,7 +503,7 @@
 		*/
 		authorization := f_tr_Authorization_AKAv1MD5(valueof(wwwAuthenticate),
 							     g_pars.user & "@" & g_pars.realm,
-							     f_sip_SipUrl_to_str(g_pars.registrar_sip_record.addr.nameAddr.addrSpec));
+							     f_sip_SipUrl_to_str(g_pars.registrar_sip_req_uri));
 		/* TODO: match Authorization from above: */
 		exp_req :=
 		tr_SIP_REGISTER(g_pars.registrar_sip_req_uri,
diff --git a/library/SIP_Templates.ttcn b/library/SIP_Templates.ttcn
index 7da56bc..56404da 100644
--- a/library/SIP_Templates.ttcn
+++ b/library/SIP_Templates.ttcn
@@ -1426,7 +1426,11 @@
 }
 
 function f_sip_SipUrl_to_str(SipUrl uri) return charstring {
-	var charstring str := uri.scheme & ":" & f_sip_HostPort_to_str(uri.hostPort);
+	var charstring str := uri.scheme & ":";
+	if (ispresent(uri.userInfo)) {
+		str := str & uri.userInfo.userOrTelephoneSubscriber & "@";
+	}
+	str := str & f_sip_HostPort_to_str(uri.hostPort);
 	return str;
 }