|A data channel also known as a "handshake" channel, is the control channel. The control channel can change everyday because it switches to a different repeater everyday. Data channels can be recognized by the continuous loud buzzing noise. This noise occurs when the mobile transmits a service request to the repeater and when the repeater detects that message, it transmits a message back to the mobile that tells the mobile that it has successfully accessed the system. The handshake is required to be completed in less than 0.03 seconds. An advantage of this is to insure that the handshake is not occurring on the wrong channel because of intermodulation. For a scanner to start trunking, you must first program in a data channel. Click on the icons below to hear the difference between the sound of a data channel and static.