In recent years, more and more individuals and organizations have started using packet based networks, such as the Internet, for communication purposes. For example, the use of VoIP and IP video conferencing are gaining in popularity since they offer both cost savings and improved functionality in the handling of the communication sessions. In order to establish communication sessions over a packet-based network, different signaling protocols have been developed that are responsible for controlling the setup, modification and teardown of data exchange sessions between users on an IP network. One such signaling protocol that is commonly used is the Session Initiation Protocol (SIP).
In order to accommodate the increased interest in communication over packet-based networks, many different vendors offer a range of different IP communication devices that are able to conduct IP communication sessions over a packet-based network. Examples of IP communication devices include ATAs, softphones, VoIP Phones and IP Private Branch Exchange (PBX) systems. While the large variety IP communication devices being offered by different vendors is appealing to consumers, different vendors often provide IP equipment that use vendor-specific signaling protocols. These vendor specific signaling protocols often create session initiation difficulties when two IP communication devices that use different signaling protocols are attempting to establish an IP communication session.
Many session initiation protocols, such as SIP, are relatively flexible standards that leave room for variations and vendor-specific extensions to be added. In some cases, these variations may not hinder the control of a communication session. However, in many circumstances, and especially when more advanced communication features such as call transfer and three-way conferencing are being requested, differences in the signaling protocols used by two communicating IP communication devices can cause difficulties in the establishment of the communication session and the proper implementation of the advanced communication features.
Against this background, it can be seen that there is a need in the industry to improve the manner in which IP communication sessions are established between different IP communication devices.