Patent ID: 7599347

Claim:
A method of enabling communication on an Internet Protocol based network which comprises: establishing a communications connection between a Session Initiation Protocol user agent and a server via a network; querying a database associated with the server, the database containing data relating to free Session Initiation Protocol ID's that are available to be allocated to the Session Initiation Protocol agent and data relating to allocated Session Initiation Protocol ID's, for determining a free Session Initiation Protocol ID that can be allocated to the Session Initiation Protocol user agent; allocating the determined free Session Initiation Protocol ID for use by the Session Initiation Protocol user agent; moving the determined free Session Initiation Protocol ID to the data relating to allocated Session Initiation Protocol ID's; and after the Session Initiation Protocol user agent to which the Session Initiation Protocol ID was originally allocated has completed a communications session using SIP, returning the Session Initiation Protocol ID to the data relating to free Session Initiation Protocol ID's for use by another Session Initiation Protocol user agent.