Found on wikipedia:
"Channel Associated Signaling (CAS), also known as Per-Trunk Signaling (PTS), is a form of digital communication signaling. As with most telecommunication signaling methods, it uses routing information to direct the payload of voice or data to its destination. With CAS signaling, this routing information is encoded and transmitted in the same channel as the payload itself. This information can be transmitted in the same band (in-band signaling) or a separate band (out-of-band signaling) to the payload."
I thought CAS was in-band signaling.
Do they mean with in-band and out-band the bands in the frequency spectrum?
Well, CAS with pulse dialing is actually out-of-band.
How it works, the A bit is toggled emulating the hook-switch in an analog telephone with rotary dial.
This is the only case that comes to mind, all the rest is in-band.