Dear IMS-experts, I am trying to reduce the complexity of the IMS implementation by disabling the functions which are not required for a pure stripped down IMS core platform. Therefore I deactivate NAT handling, RTP proxy, SBC, dispatcher etc... in a first step. Later on I will add the functions step-by step. According to the requirements. Now I discovered an inconsistency in the configuration file (kamilio.cfg) of P-CSCF. In main routing logic there is the point where P-CSCF distinguishes an originating-initial request from a terminating-initial request. This is done by the code: if (!ds_is_from_list()) { # Originating from Subscriber: route(Orig_Initial); } else { # Terminating to Subscriber: route(Term_Initial); } Unfortunately the function ds_is_from_list() is part of the dispatcher module which I want to avoid in a first step. Therefore another criterion must be used to distinguish between originating- and terminating-initial request. I therefore propose to use the pseudo-user-name "term" in the Route-URI as a distinguisher. What do you think? I am actually thinking about the correct statement (regular expression) to do that. Maybe anyone can help. BR Franz