First, I was reading in Matthew Gast's T1 – A Survival Guide about channelized T1's and channel associated signaling. Just to make sure I am understanding it correctly – CAS and robbed bit essentially refer to the same thing on a channelized T1 don't they? The bits that are robbed include the signaling bits – AB or ABCD depending on whether you have SF or ESF. Please confirm if I am understanding this correctly.
I have never worked on T1 but just E1 in México, but have read several times different books about CAS. AFAIK you are correct, except I cannot confirm your SF vs ESF statement. In the E1 world RBS is not used to implement CAS, but rather channel 16 is used to multiplex the ABCD bits for all the other channels, so ABCD update per channel arrives each 2 ms in channel 16. Moisés Silva ( moy ) -- "I do not agree with what you have to say, but I'll defend to the death your right to say it." Voltaire