Method and apparatus for improved resource allocation in ad hoc group calls

A server, comprising:

• a network interface and a processor, each communicatively coupled therebetween;
• and
• memory storing instructions that, when executed, cause the processor to:
• receive a request, through the network interface, for an ad hoc group call with another push-to-talk (PTT) system between a plurality of subscriber units comprising a plurality of Project 25 (P25) subscriber units;
• allocate resources with the another PTT system using an Inter Radio Frequency Subsystem Interface (ISSI) network to network interface (NNI) over the network interface;
• and
• identify the ad hoc group call as a single logical call for the plurality of P25 subscriber units on the ISSI NNI.

A network, comprising:

• a broadband push-to-talk (PTT) server communicatively coupled to at least one broadband subscriber unit;
• a Project 25 (P25) PTT server communicatively coupled to a plurality of P25 subscriber units;
• and
• an Inter Radio Frequency Subsystem Interface (ISSI) network to network interface (NNI) between the broadband PTT server and the P25 PTT server;
• wherein an ad hoc group call between the at least one broadband subscriber unit and the plurality of P25 subscriber units is configured as a single logical call for the plurality of P25 subscriber units on the ISSI NNI.