IMS enables wireless convergence, Part 2

While mobile phone operators have seen phenomenal growth in their market, competition has eroded their average revenue per user.

To counter this margin erosion, the operators have added Short Message Service, cameras and other data services. However, applications driven from the Internet-based services have proven elusive in part because the bandwidth required to support applications would be expensive. Furthermore, the signaling infrastructure for phones was designed for circuit-switched voice and not for data.

Third-generation wireless technology addresses the bandwidth problem, and IP Multimedia Subsystem (IMS), discussed last time, helps to solve the signaling and session control issues associated with multimedia services.

Of course, voice still remains today’s primary application for wireless telephony. By adopting Session Initiation Protocol as the signaling protocol, wireless operators have a standard that works well for voice and for data. In fact, one of the first specifications completed was for “push to talk” phone service.

Recently, Siemens announced availability of its “Push and Talk” (PaT) phone, noting that this feature “will penetrate the whole market only if information can be exchanged easily between the different mobile networks and devices. As the driving force behind group calling via mobile phone, Siemens mobile stresses compatibility for all PaT components on the basis of the IP Multimedia Subsystem.”

While PaT isn’t the only reason for IMS, it shows the industry is serious about deploying IMS-compatible components. Other applications using IMS – like instant messaging, SMS, and presence – are expected soon, enabling a smoother integration with wireline services than had been possible before IMS was introduced. According to Siemens, IMS supports “communication between the PSTN, the CS domain, ISP networks, and the Internet. It serves as the perfect digital glue for services and applications.”