Session Initiation Protocol
Wave Three software uses the Session Initiation Protocol (SIP) to communicate with other Wave Three agents, with the Wave Three server infrastructure and with other SIP enabled devices.

SIP was designed in 1996 as a signaling mechanism for creating, modifying and terminating IP based teleconferences. By 1999, the Internet Engineering Task Force (IETF) approved the protocol as an official standard. Today, the SIP Forum, an international, non-profit association formed to promote the protocol, has 32 full members and 873 participant members.

SIP was designed specifically for communication over computer networks like the Internet. The IETF approach to service deployment is simple. SIP is based on a utilitarian approach to networking; which specifies only elements of the technology that need to be specified. SIP does not know details of a session or the media that is being transmitted. SIP simply initiates, terminates and modifies sessions. Because SIP is so simple, the model scales well and may be extended into a range of architectures and implementations. Also, because the interrelation between the media types is not specified by the IETF, implementers have a great degree of autonomy in what gets sent and how it is sent.

In contrast, traditional networks like the Public Switched Telephone Network (PSTN) assume "dumb" network end points, and services are enabled by intelligence residing in centralized network switches that make it expensive and difficult to deploy new and innovative services.

The ITU, the standards body for the telephone industry, has specified H.323 as the basic signaling protocol. H.323 is really a family of protocols addressing different network functions. As a vertically-integrated suite of protocols defining every component of the network, all layers of the H.323 model are aware of and dependent on other layers. For example H.323 specifies the Q.931 standard for call setup, the H.245 specification for creating media channels and the H.263 CODEC for video. This is drastically different from the SIP model which only sets up and manages calls leaving the technology implementer to determine what types of media are transmitted, and how.

SIP has other inherent advantages in today's world of computer networks. SIP, as a protocol; closely resembles other Internet protocols including HTTP and SMTP, so SIP works well in conjunction with other Internet applications. Using SIP, audio and video become simply web applications that integrate easily into other services.

By creating an abstraction layer between services, users and devices, SIP architectures enable a range of improved features including unified communications, user interaction management and superior solutions for mobility. In the SIP model, a user’s actual physical location or address is clearly distinct from the logical address. Through the use of location, redirection and proxy servers, advanced services are enabled, including location services, video enriched commerce, web page click-to-dial and multi-media messaging with Presence.

As microprocessor power increases consistently and dramatically, developers are designing applications to take advantage of the higher capacity on the desktop and in communication devices. SIP allows the evermore-powerful network end points to realize the potential for new and innovative services by separating communication devices such as IP phones and computers from the service logic of the network.