Repeater operation helps mobile and low-power stations extend their usable range. A repeater that is available for anyone to use is called an open repeater. You should pause briefly between transmissions when using a repeater to listen for anyone wanting to break in. You should keep transmissions short when using a repeater because a long transmission may prevent someone with an emergency from using the repeater.
When using a repeater to communicate, you need to know the input frequency and offset. The usual input/output frequency separation for repeaters in the 2-meter band is 600 kHz, in the 1.25-meter band it is 1.6 MHz, and in the 70-centimeter band it is 5.0 MHz.
An autopatch is a device that allows repeater users to make telephone calls from their stations. A repeater time-out timer limits the amount of time someone can transmit on a repeater. A CTCSS (or PL) tone is a sub-audible tone, added to a carrier, which may cause a receiver to accept a signal.