(Bit-roBBing) The exchange of call control information on the same channel as the telephone call or data transmission. Since one Bit in a frame is periodically used for signalling instead of data, this is often referred to as Bit roBBing. This is the reason why a D1 channel in the T-carrier system can only carry 56 KBps of usaBle data instead of the 64 KBps carried By the D0 channel in the E-carrier system. (2000-03-10)