US : IMS (IP Multimedia Subsystems) has been around for some time, and many infrastructure vendors have invested heavily in developing IMS capabilities, solutions and products. But market acceptance has been slower than expected. Now, with the 4G standards LTE (Long Term Evolution) and WiMAX taking shape, the IMS platform has been given a new role and a niche that will carry it a considerable distance into the future.

That is because some elements of IMS such as the Home Subscriber Server (HSS) and the Policy and Charging Rule Function (PCRF) are also key components in the LTE core architecture. Similar elements are also defined in WiMAX. These elements are required to enable the end-to-end QoS and dynamic charging capabilities required for the next generation of mobile data services.

“IMS, which enables the rapid creation and deployment of new services and applications, was rather slow to take off because operators weren’t quite sure how they were going to use it,” says ABI Research senior analyst Nadine Manjaro. “They struggled to find a business case for it. Now, the FCC in the United States has declared that winners of  700MHz spectrum must meet open application and device criteria. Verizon won most of that band in the recent auction, and will use it for LTE. Verizon launched its Open Development Initiative (ODI) based on IMS architecture called ‘Advance to IMS’ in March 2008. This interface for applications and devices will enable the openness that the FCC requires.”

Many operators and vendors are now moving to an open applications architecture: Sprint has mentioned it in reference to its application strategy and uses IMS as the base architecture for its High Performance Push to Talk (HPPTT) network scheduled to launch in June 2008. Nokia mentioned open devices and applications as a key initiative in its migration strategy. IMS will help to ease the transition to open development, and will be a fundamental part of future LTE and WiMAX networks.

These and many other aspects of IMS are discussed in ABI Research’s recent study, “IMS Core Networks: A Dynamic Service-Based Architecture”. It provides a comprehensive look at the IMS activities in wireline and wireless access networks, offering insight into how operators are using IMS, and its role in future network migration.