Originally Posted by mforrence

I agree that it was how you were taught. My version is that a DS1 is the physical 1.544Meg pipe that can either be administered as a T1 or a PRI. The big difference in the voice world being that with T1 all of the call setup, connection and teardown signallling is done within the specific channel in question (i.e. if a call is being made on channel 7, then all signalling is done within channel 7.) With a PRI all of the signalling is done on the D channel - ususally channel 24, regardless of which channel will bear the call. Hence, if a call is to be made on channel 7, one end tells the other end all of the specifics via data packets on channel 24. That's how I teach my folks...

Mike