Hello Adel..

Push to Talk functionality is not a built-in part of the Concierge OS, and therefore is not directly accessible through the Android or Conciergie SDKs.  There is, however, nothing that precludes third parties from writing PTT applications that run on the Concierge.  The Concierge generic demo, for instance, includes a very simple Push to Talk application built from an outdated version of MSI's Team Express client.  Making use of an updated version of the MSI PTT capabilities to create a more full-featured Concierge PTT application for retail customers should be entirely possible with the current release of the CC5000.

Thanks,
Kevin