Many two-way radios provide the ability to set the device on silent or vibrating modes. This feature is sometimes called ring alert and helps the user to select audible, vibrating, or silent mode for the radio.
If the radio is set to audible mode, the radio rings with the set call tone for the incoming transmissions.
If the mode is set to vibrating, the radio only vibrates and the user feels the vibrations and the screen blinks when there is an incoming transmission.
In the silent ring alert mode , the radio disables all the beeps and tones. In this mode, the radio will indicate an incoming transmission without making an audible alert of any type and only the display will flash several times. This feature is very helpful for the people whose work cannot be disrupted by noise e.g. soldiers, hunters, etc.