The invention concerns a call control method for IP based telephone services and a call control server providing IP based telephone services within a communication network. The call control server assigns two or more IP telephone terminals to a telephone number commonly shared by these IP telephone terminals. It stores IP address data of these IP telephone terminals in the registry of this call control server which is responsible of VoIP calls directed to this telephone number. An IP telephone terminal transmits a presence message to the call control server when a presence button of the IP telephone terminal is pressed. VoIP calls directed to the telephone number are routed to that one of the IP telephone terminals assigned to the telephone number, the call control server has received the presence message from.