Universal agent log-in using a sip registrar

A method and apparatus are provided for registering an agent of an automatic contact distribution system for receiving calls. The method includes the steps of providing a file containing a file identifier and a plurality of contact addresses within a registration server where each contact address identifies a communication port through which the agent may be contacted under a respective communication protocol, the presence server receiving a SIP REGISTRATION message from the agent where the SIP REGISTRATION message contains the identifier of the file, but not the file itself and the registration server simultaneously registering the agent with the plurality of contact addresses under each of the respective communication protocols in response to the SIP REGISTRATION message.