Disclosed is a method in an application server. A request for initiating a communication session is received, and responsive to the request including a first service identifier pertaining to a service not supported by the application server, the first service identifier is removed from the request. A response to the request is received, and responsive to having removed the first service identifier from the request and the response including a second service identifier pertaining to the same service as the first service identifier, the second service identifier is removed from the response.