hi all, im a bit of a retard when it comes to the technical side of radio communications

so sorry if this question seems a little lame. sometimes when you listen to the LAPD radios on movies or on a scanner you hear a bleeping noise transmitted over the radio, when the cop presses the PTT button. its supposed to let all the other ppl on channel know that someone is about to transmit, so dnt say anything...or something like that

does anyone know the actual term for this type of thing, and if it can be programmed into a Motorola GP328 (Australia's version of the Motorola HT750). thanks in advance to any help with my retard's question
