Push-to-talk standard approved

The push-to-talk technology that lets mobile callers talk instantly with the push of a button has been standardized, a mobile industry group announced Tuesday at the CommunicAsia conference in Singapore.

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The Open Mobile Alliance's push-to-talk standard, called POC 1.0, has received the group's final approval, giving sellers of handsets and mobile application servers a way to make push-to-talk work across a multivendor network. It will also let subscribers make push-to-talk calls to people on other carriers' networks, said Jari Alvinen, chairman of the board of the OMA.

Push-to-talk makes a mobile phone work like a walkie-talkie. A caller chooses from among a group of available buddies or coworkers, presses a button and immediately starts talking.

It was popularized by U.S. mobile carrier Nextel, which runs the service over a network based on iDEN technology. But the technology has not been widely implemented on the world's major cellular systems, GSM (Global System for Mobile Communications) or CDMA (Code-Division Multiple Access), according to Ken Rehbehn, an analyst at Current Analysis Inc., in Sterling, Virginia.

The OMA released the standard in May 2005 as a Candidate Enabler Release. It is now an Approved Enabler Release, the final stage for an OMA standard. Over the past year, vendors have brought 22 implementations on clients and eight implementations on servers to OMA interoperability testing events. The group will continue hosting interoperability events but will not certify products, Alvinen said.

In addition to one-on-one conversations, POC can be used for group calls. It includes specifications for functions such as ad hoc group communication, barring of incoming sessions and on-demand session handling for one-to-one and one-to-many calls.

POC is essentially a VOIP (voice over Internet Protocol) service, converting voice signals into packets and transmitting them over a mobile data network.

With a standard in place, it should be easier and less expensive for carriers to set up push-to-talk services for their subscribers, Current Analysis's Rehbehn said. Most push-to-talk implementations on systems other than iDEN have been expensive and not very successful, he said.

Rehbehn expects most carriers to adopt the OMA standard, with the exception of Sprint Nextel. That company is expected eventually to replace Nextel's iDEN network with CDMA, which Sprint has now, and use the QChat push-to-talk system developed by Qualcomm, he said.

The OMA's timing is good, because the next versions of both GSM and CDMA networks set to come on line will solve problems such as latency that have dogged push-to-talk so far, Rehbehn said. HSDPA (High-Speed Downlink Packet Access) is starting to be rolled out now, and EV-DO (Evolution-Data Optimized) Revision A is expected in commercial networks starting this year.

However, operators probably won't allow POC calls outside their networks any time soon because of technical challenges involving billing and logistics, Rehbehn added.

The OMA, established in 2002, boasts a membership of nearly 400 that includes most of the major mobile vendors and operators, such as Nokia, Motorola, Lucent Technologies, Qualcomm, Vodafone Group, T-Mobile International, and Cingular Wireless.