PTT mode (Push-to talk)

Transmit

Radio is on transmit mode while depressing button.

Receive

Releasing button changes radio to receive/standby mode.

SPT mode (Smart PTT)

Transmit

Depress once the button keeps radio on transmit mode with hands free.

Receive

Another depress the button releases radio to receive/standby mode.

ASO (Auto-shut-off)

While SPT mode, the unit automatically returns to receive/standby mode after three minutes.