Bit robbing

Bit robbing: In digital carrier systems, the practice or technique of preempting, at regular intervals and for the purpose of transmitting signaling information, one digit time slot that (a) is associated with the given user channel for which signaling is required, and (b) is used primarily for transporting encoded speech via that channel.

Note 1: Bit robbing is an option in networks compatible with T-carrier, e.g., an ISDN.

Note 2: In conventional T-carrier systems, bit robbing uses, in every sixth frame, the time slot associated with the least significant bit. Synonym speech digit signaling.

Source: from Federal Standard 1037C