"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", says 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".

Recent testing between Ericsson infrastructure and Siemens mobile devices 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.

"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. In 2005 more than 10 handsets from Siemens will support push to talk. In nearly all handsets starting from the C class a client for push to talk will be integrated showing our commitment to this new form of communication."

Push to talk calls are one-way communication: while one person speaks, the other(s) listen. The right to speak is granted by pressing a push to talk key on a first come-first served basis. The service will run over standard GPRS networks where operator supports this functionality.