asterisk: IMS: validate P-Preferred-Service in INVITE

Change-Id: Iaa219d7b16965b27cd62ec27d810cb490dbc7a5a
diff --git a/library/SIP_Templates.ttcn b/library/SIP_Templates.ttcn
index d0210d1..ce5998b 100644
--- a/library/SIP_Templates.ttcn
+++ b/library/SIP_Templates.ttcn
@@ -284,6 +284,12 @@
 	p_assoc_uris := p_assoc_uris
 }
 
+// [RFC6050]
+template (present) P_Preferred_Service tr_P_Preferred_Service(template (present) Service_ID_List p_ps := ?) := {
+	fieldName := P_PREFERRED_SERVICE_E,
+	p_ps := p_ps
+}
+
 // RFC 3262
 template (value) RAck ts_RAck(template (value) integer response_num,
 			      template (value) integer seq_nr,