With a carrier under test and a product already shipping, Telcordia announced this week the availability of what it says is the first commercially available IMS product that supports the call continuity control function, which allows call handoffs to fixed/mobile, Wi-Fi or IP networks.

“The big news here is that we have an IMS solutions available now for CDMA networks, with one coming for GSM and UMTS, and it's been sold to a major operator,” said Grant Lenahan, executive director of wireless mobility and chief strategist at Telcordia.

Seamless Mobility is part of Telcordia’s Maestro IMS portfolio and is an application, albeit a big one, that runs on its Converged Application Server. It allows operators to offer a solution based on fixed/mobile convergence that its customers with dual-mode phones can use to hand off calls between Wi-Fi, fixed/mobile networks and/or SIP-enabled broadband networks. Users can use a single personal mobile device in the home, office or on the road across all network technologies.

“Obviously we are dependent, like everyone else in the world, on having dual-mode handsets,” Lenahan said. “But some handset manufacturers are extremely aggressive.”

And CDMA network operators are being aggressive as well, Lenahan said, because there is no unlicensed mobile access (UMA)-like alternative for them as there is for GSM operators, as inefficient as it is in extending their networks into the IP realm.

“Some GSM operators nevertheless are doing that because it is the fastest way to get to market,” Lenahan said.

Using the 3GPP and 3GPP2 standards for voice call continuity and interoperability, the Seamless Mobility solution interworks with a wide variety of dual-mode handsets and multivendor environments.

Jim Alfieri, principal solution architect with responsibility for the Seamless Mobility solution, said there is more to handoffs and handsets in the product. It allows users whose identities are registered on multiple networks to pick their mode of communication.

“It lets users figure out what network they are on and use the system to terminate to a fixed phone or a mobile phone instead of a Wi-Fi device,” Alfieri said.

Seamless Mobility does this in part by using standard SS7 TCAP interfaces to the elements within the existing wireless network. “Because we stay at the control level and speak both SS7 and SIP, we are at a unique place to hand things off fairly elegantly to either a circuit-switched network or to an IMS network,” Lenahan said.