The present invention is aimed to carry out an effective handover between a first and a second serving call control servers in order to fit suitable server capabilities for servicing a user, as well as to provide a mechanism whereby a subscriber server may upgrade the selection criteria for assigning the second serving call control server. Therefore, the present invention provides a new method and enhanced servers for re-assigning the second serving call control server, whereby the still ongoing sessions for the user in the first serving call control server are kept alive, and where a serving call control server is arranged to report towards the subscriber server what portions of a user profile are not understood or not supported at said serving call control server.