Next Generation Wireless Applications: Creating Mobile Applications in a Web 2.0 and Mobile 2.0 World, 2nd Edition

14.9 END HERE: BEYOND VoIP – APPLICATION SERVERS

SIP is largely a peer-to-peer (P2P) signalling method. This means that the logic (software) responsible for processing the call flow sits at the end-points (edge) of the network connection (i.e. it resides in the devices). It is true, SIP and IMS do rely on intervening servers, but keep in mind that these servers provide the necessary assistance for two (or more) SIP agents to find each other. Afterwards, the two agents are left to negotiate and collaborate at their discretion.

The P2P architecture of SIP is very conducive to supporting powerful new services, simply because there's no messy integration into some behemoth centralised core (usually with archaic protocols and programming models). More or less, just granting access to the IMS network is enough to allow a powerful new service to be introduced to its users. This is indeed an exciting prospect for both IMS network providers and third-party application providers. Moreover, because SIP and IMS are open standards, third-party providers are encouraged by the prospect of developing applications that can run on many networks. Developing SIP-aware applications is becoming as easy as developing web applications. Furthermore, the growing sophistication and power of supporting software technologies, like J2EE, make it easy and low cost to develop scalable carrier-class applications on a relatively low budget. In theory, the path to producing scalable IMS applications is an increasingly ...