“Interoperability is vital for the successful adoption of push to talk in the market,” says Clemens Joos, President Mobile Devices, Siemens Communications. “That is why all push to talk capable mobile phones from Siemens guarantee access to IMS networks and are equipped with an open industry-standard client . In 2005, more than 10 handsets from Siemens will support push to talk. In nearly all handsets starting from C class a client for push to talk will be integrated showing our commitment to this new form of communication.”

Recent testing between Ericsson infrastructure and Siemens handsets were carried out with two currently offered push to talk enabled devices, the CX70 and C70 which are commercially available. The CL75, CX75, CF75, M75, and SXG75 that were presented during CeBIT 2005 will also have push to talk incorporated.

”One of the core strengths with an IMS solution for standard-based push to talk is its ability to enable compatibility between a range of devices delivered from different vendors” commented Björn Olsson, Executive Vice President and General Manager, Business Unit Systems at Ericsson . “Handset diversity is important for service adoption and we are very pleased to see a new line of handsets having finalized testing with our push to talk solution.”

Push to talk calls are one-way communication for two person- or multi-user situations: while one person speaks, the other(s) listen. First, the user selects the people he or she wants to talk to from a list. At the push of a button, all of these previously defined addressees immediately receive an invitation which they can accept or decline. As soon as the participants have confirmed, the initial caller pushes the push to talk button and starts the chat, which everyone hears simultaneously. There is no time-consuming call setup, because the “Always On” feature of the GPRS network maintains the connection all along. Any group member can reply immediately by pressing the push to talk button. The communication can only go in one direction at a time, however: whoever presses the push to talk button first, talks first.