Magnus Furustam, IMS Program Director at Ericsson, says: "If operators want to continue to be a major provider of the communications experience, IMS is the standardized way to do it." The IMS standard was developed by the Third Generation Partnership Program (3GPP) in an effort to define the functionality necessary for delivering IP-based services with carrier-grade quality.

From its long experience of IMS, Ericsson is aware of the task operators face when going from a telecom-centric environment to an all-IP environment.

ere are a host of different challenges facing operators in the process of evolving to all-IP. One challenge will be to ensure that new end-user features being developed in the system are mirrored in the multitude of devices available in an IMS-enabled world. They also need to investigate whether their organization is ready to introduce potentially disruptive IP technology into its telecom-centric operations.

But while implementing standards for IMS is a key component in the evolution to all-IP, Furustam says it is not the whole equation. When planning for a commercial launch of IMS-based services, there needs to be a market interest, as well as an adequate penetration of terminals with IMS capabilities.

Examples of new IMS-based services include image and picture sharing in combination with circuit-switched voice, presence-enabled address books showing user availability and connection-type information, and the ability to hold push-to-talk sessions between multiple users. "Eventually, operators are going to run their cash cow, telephony, over IMS," Furustam says. "To do this, they need to feel that they are well prepared."

A phased, moderated approach to this significant shift in technology is the most advisable way forward. It is not recommended to move profitable services from proven circuit-switch technology to packet-switch technology from day one without strong business reasons for doing so. One way to achieve more structure in the shift to IP is to have a reference IMS architecture in mind when making decisions on existing systems.

"All new purchases that operators make in the core network and service layer will, of course, not be IMS-based, but they could be seen in an IMS context with a clear evolutionary path," Furustam says.