Embodiments include a push-to-talk over cellular (PTToC) communication system and method having one or more push-to-talk (PTT) servers that control all PTT functionality for a set of users for receiving and transmitting audio communication over the Internet. A software defined radio (SDR) system is connected to the PTT server by means of a gateway and an internet gateway connection. The SDR system has software in a central processing unit which perform basic radio, audio frequency, and Internet networking functions, wide area connection, and routing functions that map radio channels to PTT talk groups by means of a radio channel routing table. The gateway adapts digitized audio between the SDR system and the PTT server and has a management application program interface client used by a central management entity to control the SDR system.