Reminiscing our first internet connections (WAS) Re: akamai yesterday - what in the world was that

Mon Feb 17 20:43:02 UTC 2020

A PRI was and still is 23B+D, not 24 2B+D lines.

23B+D (ISDN PRI or Primary Rate Interface) is  23x64 kbps bearer 
channels and a 64 kbps Delta channel carried on a B8ZS T1

You could carry additional groups of 24 B channels using NFAS, or 
Non-Facility Associated Signalling where the D channel on the first 
PRI carried the call setup and teardown information for the 
additional B channels on up to 20 PRI circuits.

2B+D (ISDN BRI or Basic Rate Interface) 2x64 kbps bearer channels and 
a 16 kbps Delta channel carried on an 144 kbps 2B1Q U interface.

At 02:58 PM 27/01/2020, bzs at theworld.com wrote:
>FWIW bulk dial-up lines were often brought in as PRIs which were 24
>ISDN 2B+D lines on basically a T1 (1.544mbps) and then you could break
>those out to serial lines.