Hi, I have Kamailio 5.1 and I'm using the topology hiding module (topoh) that is configured as the following: modparam("topoh", "mask_key", "...") modparam("topoh", "uparam_name", "....") modparam("topoh", "uri_prefix_checks", 0) Unfortunately Fanvil SIP phone modifies the remote party Contact's URI before it puts it as R-URI in the re-INVITE request. For example, The remote party Contact header: Contact: <sip:127.0.0.8;tr=sr-O2Sdn60d3qrt3otz3o7L.6pF.6mUr6lF3qpd> The re-INVITE request line: INVITE sip:127.0.0.8;tr=sr-O2Sdn60d3qrt3otz3o7L.6pF.6mUr6lF3qpd;user=phone SIP/2.0 As you can see, ";user=phone" was added. As result of that Kamailio tries to send the request to 127.0.0.8. If I disable sending 'user=phone' in Fanvil configuration then everything works well. I assumed that if uri_prefix_checks=0 then the topoh module should take rid of such URI modifications. Am I wrong? Is there any way to solve the problem except to modify the endpoint configuration? Best regards, Leonid Fainshtein