Technology Review writes about IP for Multimedia System (IMS):
From simple phone calls, voice mail and call waiting, to wireless text messaging and multimedia downloads, most existing telecom services were designed to perform their specific functions as if walled off into distinct silos on the network.
It matters little that most network traffic is now digital. For example, despite the growth of phone services based on Internet standards — known as Voice over Internet Protocol, or VoIP — most wireline and wireless calls aren’t transmitted in IP from start-to-finish; calls get converted to traditional phone protocols on either or both ends.
And while a growing number of non-voice services are IP-based, interspersing their digital packets down a shared network pipe, many applications still need to create a virtual ”session,” not unlike the path of a regular phone call, between a user’s device and the network.
IMS attempts to knock down these silos by introducing a common interface for creating sessions. That way, data can be intertwined or bridged across networks to different devices.