Continuity Check

In telecommunications, a continuity check is a test performed to verify that a path exists before starting speech or data transmissions. Continuity refers to the path’s existence. If continuity doesn't exist, then either the transmission is aborted or the sender attempts to reestablish communication. Continuity checks are used in channel-associated signaling (CAS), where signals are sent over the same channel used for data transmission. Continuity checks aren't present by default in common-channel signaling (CCS), an alternative to CAS where signals are sent via a different channel than the one used for data transmission, but can be implemented if desired.