Avail understands that in systems where myAvail controls operators’ access to the voice radio, it is critical that operators continue to have voice communications if myAvail fails.
Closed Mic refers to cases where myAvail manages operators access to voice communications through the RTT (Request to Talk) and the PRTT (Priority Request to Talk) commands from the MDT. Operators must request permission through the MDT before they pick up their handset and start talking to the dispatcher or to other operators. Operators cannot talk directly to each other, a supervisor, or the dispatcher without dispatcher permission. Also, operators only hear calls that the dispatcher has specifically allowed for that vehicle. Closed Mic operation is optional for private radio systems, but it is required for VoIP.
The Communications Control Module (CCM) device has a ‘watchdog’ mechanism that can detect a myAvail failure. The CCM periodically pings the IVU, which in turn pings the MDT. The IVU responds to the CCM, and that response includes the MDT status. If the CCM does not receive an IVU response within a timeout period, or receives a response which indicates an MDT problem, the CCM resets power to the MDT and IVU. This action causes them both to reboot, re-establish connectivity, and re-start their processing. This failsafe mechanism helps the system recover from unexpected connection and processing problems. If this process does not restore normal operations, communications go into a “Fallback” mode automatically.
In a private radio system, the radio fallbacks to Open Mic. In an Open Mic configuration, everyone on the same frequency hears everyone else talking. No prior action is needed to speak on the radio.
VoIP communications has its own fallback. The VoIP processing is isolated from the MDT-IVU units. When the central system has a communication problem, the CCM puts the VoIP processing into a voice-fallback mode that allows the driver to use the handset to make and receive direct voice calls with dispatch without obtaining permission.
When vehicles go into voice fallback, IT personnel must determine whether the problem exists in the communications connection to the tower, communications software, radio equipment, or cellular provider. If your property’s support agreement includes the radio system, contact Avail Support and they will have a radio shop check the tower.
If the vehicles are not able to communicate over the radio data channel system, but the vehicles continue in “Closed Mic” operation, then disable the WiNG service. This action forces vehicles to voice fallback until the problem is resolved.