Most T199’s have the issue that when they have been idle for a while (depends from device to device, some 20 min, some 4 hours) the PTT gives an error when pressing it.
It seems that the device gets out of its selected channel and goes back to the channel overview window (which you can’t see obviously). So when you press the PPT button Zello doesn’t know on what channel it should broadcast on, hence the error sound.
We found a solution for that by disabling every type of screen security on the T199. Configuration can be found in the link below.
If you have this issue and it’s not solved with the configuration described, please let us know. Please make sure that your device is configured exactly like in the manual, this way we can exclude other errors. Thnx!