US Patent 7440440 Method and system for device-based call park and pick-up

A method for call parking in a network telephony system is disclosed. A first user agent and a second user agent establish a communication session, and the second user agent enters a call park number to initiate a call park of the communication session. Subsequently, the call park number and the location of the second user agent are sent to a server, which authorizes the second user agent for call parking. The server then registers the call park number, and the communication session between the first and second user agents is parked. When a third user agent wants to pick up the communication session, the third user agent calls the server by entering the call park number. The server then routes the third user agent to the second user agent, which in turn refers the third user agent to the first user agent. The first and third user agents then establish their own communication session, the communication session between the first and second user agents is terminated, and the call park number is deregistered.