in-band signalling

in-band signalling
bit-robbing
channel associated signaling
in-band signaling

   <communications> (Or CAS, channel associated signaling)
   Transmission of control signals in the same channel as data.
   This is commonly used in the {Public Switched Telephone
   Network} where the same pair of wires carry both voice and
   control signals (e.g. dialling, ringing).  Another example is
   the use on a computer {serial line} of Control-S and Control-Q
   characters for {flow control} as opposed to {hardware flow
   control} which would be out-of-band signalling.

   In digital communications, in-band signalling often uses
   "bit-robbing" where, for example, one {bit} in each {frame} is
   used for signalling instead of data.  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.

   (2007-01-26)