Channel Associated Signaling (CAS) signaling is a form of digital communication signaling. As with most telecommunication signaling methods, it uses routing information to direct the payload of voice or data to its destination. With CAS signaling, this routing information is encoded and transmitted along the same link as the payload itself. This results in lower available bandwidth for the payload, normally reducing a 64 kbit/s DS0 to 56 kbit/s. Because of this, and the inherent security benefits of separating the control lines from the payload, most current telecom systems rely more on the out-of-band signaling. See Common Channel Signaling.

The most common implementation of CAS is robbed bit signaling.

Computer and telecommunication standards

Channel-Associated Signalling