FS-3842 here is the from and contact change but I can't remove the user agent but I added a new param to the gateway config called options_user_agent to set something specific

src/mod/endpoints/mod_sofia/mod_sofia.h

@@ -454,7 +454,9 @@ struct sofia_gateway {
 	char *auth_username;
 	char *register_password;
 	char *register_from;
-	char *options_uri;
+	char *options_from_uri;
+	char *options_to_uri;
+	char *options_user_agent;
 	char *register_contact;
 	char *extension;
 	char *real_extension;