EnglishBasic operation 17Transmit timerYour radio may have a transmit timer that limits the amountof time you can transmit continuously. When the transmittimer is about to expire, the red LED flashes and the radiogives three beeps. You must release the PTT before you cantransmit again.Note: Your radio may be unable to transmit for a short timeafter the transmit timer has expired.Receiving a callWhen there is valid activity on your radio’s currently selectedchannel or group, the radio then unmutes and you canhear the call.If the incoming call contains special signalling that matchesthe signalling programmed for your radio, the green LEDflashes and your radio may give a ringing tone.What you hear on a channelYour radio may be programmed so that you hear all conversa-tions on a channel, or your user group may be segregated fromother user groups by using special signalling. The specialsignalling is used to control the muting and unmuting of yourradio, so that your radio is muted when other user groups aretalking and unmuted for members of your user group.There are two muting controls that operate in your radio:■ signalling mute, and■ squelch.Signalling muteThe radio’s signalling mute only allows the radio to unmute ifthe incoming call carries the tones specific to your usergroup. Your user group may use tones that are either audible,subaudible or both.