The PoC function enables mobile phones to be used like walkie-talkies, providing communication at the touch of a button. Already popular in North America, PoC is poised for growth in Europe and in Asia - but interoperability is a key factor to such broad-based acceptance.  

The first technical standard specification for Push-to-Talk - PoC Phase One - was submitted to the Open Mobile Alliance (OMA) in August 2003. Ericsson, Motorola, Siemens and Sony Ericsson are promoting a final version of the PoC standard through the OMA.

Today, the industry leaders take the next step by successfully starting joint interoperability tests to help speed delivery of compatible PoC solutions to network operators.  The first interoperable products and solutions are expected to be introduced in Q2 2004.  Other manufacturers are encouraged to join the interoperability tests to help ensure compatibility between devices and PoC servers across vendors.

About Push-to-Talk over Cellular service
Push-to-Talk over Cellular is similar to a walkie-talkie experience; it is a means of quick one-to-one or group communication. Instead of dialing a number to start a conversation, with one push of a button you simply go to a "buddy list" and select the person you want to contact. Push the button again, talk, and your voice is heard by the recipient.
You can also create group calls so everyone on your buddy list can hear your message simultaneously - just as in a telephone conference. Instead of having to SMS or call each recipient individually, a push of the key is all it takes to send a message directly to an entire circle of friends or work colleagues, for example.
For network operators, PoC opens up a whole new realm of voice services, as it significantly enhances telephone service. Experience has proven that consumers with PoC features on their phone tend to become more engaged with their handset potentially providing mobile operators with a new source of revenue - potentially a high return from existing infrastructure at a relatively low risk. 
And, PoC service fits a variety of markets - from consumers who want quick communication to small, medium and large enterprises that need frequent intermediate contacts.

About PoC Phase One Specification
The PoC Phase One Specification was developed by leading wireless vendors to ensure an interoperable Push-to-Talk solution over standard cellular networks. The specification is intended to help drive rapid uptake of PoC by enabling a simple, seamless Push-to-Talk experience for end-users.
The Open Mobile Alliance (OMA) is further enhancing this specification based on wider industry feedback. Multiple vendors are developing products according to the existing PoC specification.
The ongoing work in OMA indicates that some new functionality will be added in the future, for example the Network-to-Network Interface (NNI) that enables inter-operator communication.