por lo que entiendo de tu pregunta:
en el modo expert;
Signaling menu; en MDC Systems
l opcion PTT Sidetone short (o long o none)
Choices
Functionality
None:
Long:
When enabled, causes the radio to sound a continuous alert tone, from the time the PTT button is pressed, until the time that the Signaling System data packet is transmitted.
Short:
When enabled, causes the radio to sound one short alert tone, after the PTT button is pressed, and immediately following the Signaling System data packet being transmitted.
Suerte