Importance

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Abstract

A telecommunications system is described which allows a push-to-talk: over cellular (PoC) communication session to be established between PoC Clients comprised in respective mobile terminals (1A, 1A′, 1B). The PoC Clients form a group of devices between which a PoC communication session is established. A single controlling PoC function (22B) controls the admission of new members to the PoC communication session and the removal of members from the PoC communication session. Each PoC Client communicates with the PoC controlling function (22B) via a respective PoC participating function (20A, 20A′, 20B). In accordance with an advantageous feature of the embodiment described, the controlling PoC function (22B) issues a Talk Burst Granted message having a modified form to a PoC Client (via its associated PoC participating function) when that client is given permission to transmit a talk burst. The modified Talk Burst Granted message includes an indication of the number of active members in the PoC communication session. This information is extracted by the relevant PoC participating function and enables that PoC participating function to determine the number of PoC Clients to which the talk burst originating from its PoC Client will be transmitted. This enables the PoC participating function to provide an indication to its PoC Client of the number of PoC Clients to which its talk bursts will be transmitted and/or to cause a charge to be rendered to the user of its PoC Client in accordance with the number of recipients.

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First Claim