I believe you are speaking of the ESF data link. In the public telephone
network, it is not used for "overhead channel signaling." It is used for
continuously transmitting performance report messages, when activated.
The stolen bits are at the DS0 level; not the DS1. And they happen
with "CT1" aka 24 B channels on a DS1. It's a carryover from E&M
signalling, itself invented about the time of that squabble with
the Spanish Armada.
Now, PRI is more common than CT1; it has twenty three 64Kbps
B channels and a separate 64Kbps D (signalling) channel.
PRI (23B + D) is *not* at all common except, perhaps, in private networks.
The POTS network has been transitioning from robbed bit signaling to Common
Channel Inter-office Signaling, CCIS for many years. Last I heard,
Signaling System 7 handled the CCIS functions, CCIS uses *none* of the bits
of the channels nor their parent DS1. In fact, bandwidth for a call is not
assigned until CCIS has determined that the call has a high degree of
potential for completion.
Don