A method of establishing a media stream-based communication session, comprising: initiating a session request from a first endpoint communication device employing an instant messaging client and coupled to a packet based communication network; processing said session request including emulating said instant messaging client for a second endpoint communication device coupled to said packet based communication network, said second endpoint communication device being a non-instant messaging based communication device; and said emulation including maintaining a status of said second endpoint communication device and providing an indication of availability of said second endpoint communication device to said first endpoint communication device prior to a session request; and receiving said session request from an instant messaging client of said first endpoint communication device including a user identification associated with said second endpoint communication device; correlating said user identification to a directory number and routing information for said second endpoint communication device; processing instant messaging messages for said second endpoint communication device compatible with said instant messaging client of said first endpoint communication device based upon said availability of said second endpoint communication device; notifying said second endpoint communication device of said session request employing non-instant messaging based signaling in accordance with said routing information; establishing a media stream-based communication session between said first and second endpoint communication devices (660, 624) in response to said session request, after receiving an answer indication from said instant messaging client of said first endpoint communication device in response to an initiation of said media stream-based communication session and provide acknowledgement thereto. initiating a session request from a first endpoint communication device employing an instant messaging client and coupled to a packet based communication network; processing said session request including emulating said instant messaging client for a second endpoint communication device coupled to said packet based communication network, said second endpoint communication device being a non-instant messaging based communication device; and said emulation including maintaining a status of said second endpoint communication device and providing an indication of availability of said second endpoint communication device to said first endpoint communication device prior to a session request; and receiving said session request from an instant messaging client of said first endpoint communication device including a user identification associated with said second endpoint communication device; correlating said user identification to a directory number and routing information for said second endpoint communication device; processing instant messaging messages for said second endpoint communication device compatible with said instant messaging client of said first endpoint communication device based upon said availability of said second endpoint communication device; notifying said second endpoint communication device of said session request employing non-instant messaging based signaling in accordance with said routing information; establishing a media stream-based communication session between said first and second endpoint communication devices (660, 624) in response to said session request, after receiving an answer indication from said instant messaging client of said first endpoint communication device in response to an initiation of said media stream-based communication session and provide acknowledgement thereto.