A first mobile radio (104, 108, 110) comprising: a first wireless communication interface for communicating with a first wireless network; a second wireless communication interface for communicating with a second wireless network; a push-to-talk PTT key; a microphone; a processor; and data storage containing instructions executable by the processor for causing the first mobile radio (104, 108, 110) to carry out a set of functions, the set of functions comprising: receiving, via the microphone, audio input and digitally encoding the audio input to form communication media;determining whether the PTT key is in an activated or de-activated state for selecting between the first wireless communication interface and the second wireless communication interface as a binary function of the activation or deactivation state of the PTT key; selecting, as a function of the determined state of the PTT key, one of a first talkgroup on the first wireless network and a second talkgroup on the second wireless network as a target talkgroup to transmit the communication media to; transmitting the communication media, via the first wireless communication interface, to the first talkgroup on the first wireless network and not to the second talkgroup on the second wireless network when the PTT key is determined to be activated; and transmitting the communication media, via the second wireless communication interface, to the second talkgroup on the second wireless network and not to the first talkgroup on the first wireless network when the PTT key is determined to be deactivated. a first wireless communication interface for communicating with a first wireless network; a second wireless communication interface for communicating with a second wireless network; a push-to-talk PTT key; a microphone; a processor; and data storage containing instructions executable by the processor for causing the first mobile radio (104, 108, 110) to carry out a set of functions, the set of functions comprising: receiving, via the microphone, audio input and digitally encoding the audio input to form communication media;determining whether the PTT key is in an activated or de-activated state for selecting between the first wireless communication interface and the second wireless communication interface as a binary function of the activation or deactivation state of the PTT key; selecting, as a function of the determined state of the PTT key, one of a first talkgroup on the first wireless network and a second talkgroup on the second wireless network as a target talkgroup to transmit the communication media to; transmitting the communication media, via the first wireless communication interface, to the first talkgroup on the first wireless network and not to the second talkgroup on the second wireless network when the PTT key is determined to be activated; and transmitting the communication media, via the second wireless communication interface, to the second talkgroup on the second wireless network and not to the first talkgroup on the first wireless network when the PTT key is determined to be deactivated. receiving, via the microphone, audio input and digitally encoding the audio input to form communication media;determining whether the PTT key is in an activated or de-activated state for selecting between the first wireless communication interface and the second wireless communication interface as a binary function of the activation or deactivation state of the PTT key; selecting, as a function of the determined state of the PTT key, one of a first talkgroup on the first wireless network and a second talkgroup on the second wireless network as a target talkgroup to transmit the communication media to; transmitting the communication media, via the first wireless communication interface, to the first talkgroup on the first wireless network and not to the second talkgroup on the second wireless network when the PTT key is determined to be activated; and transmitting the communication media, via the second wireless communication interface, to the second talkgroup on the second wireless network and not to the first talkgroup on the first wireless network when the PTT key is determined to be deactivated.