[_wmd]

I can't speak for early early dial up infrastructure, but by the turn of the century the equipment involved was not all that impressive to look at.

A typical configuration would terminate the analogue lines over ISDN, which supported somewhere up to 30 B channels ('voice calls') over a single cable, running alongside one or two Ethernet cables to a single router with one or more modem option cards installed.

We had Cisco boxes in the last place I worked that handled dialup, looking pretty much like this: http://www.ciscomax.com/datasheets/3600/Cisco_3640.jpg

[aidenn0]

Are you sure you're not thinking of T-1 (24 B channels) rather than ISDN which was most typically 1 or 2 B channels?

[edit]

ISDN is a catch-all term tat included BRI (2 B channels) and T-1 (24 B channels) and E-1 (30 B channels) so the parent comment is correct.

[jsjohnst]

Your edit mostly got it right with the exception that it wasn't commonly called a T-1 or E-1 and the numbers are slightly off.

* ISDN BRI = two 64k B channels and one 16k D channel

* ISDN PRI over T1 = twenty three 64K B channels and one 64k D channel

* ISDN PRI over E1 = thirty 64k B channels and one 64k D channel (time slot 0 on the E1 was used as a sync channel and wasn't considered a B or D)

T1/E1 was considered an analog circuit with 24 or 32 respective 64kbps voice channels using in band signaling effectively limiting each channel to 56k. ISDN PRI used the same cabling and channel separation, but instead ran a digital circuit with out of band signaling enabling the full 64k to be available for voice and data. ISDN PRI (and BRI) also allowed the option to be packet based (similar to X.25) rather than circuit switched for data transmission.

[aidenn0]

In the 90s in my little corner of the mid Atlantic US at least, it was very commonly called a T1 or DS1 and the terms were used interchangeably even though they refer to slightly different things (at least by sysadmins; use the terms wrong around a telecom equipment engineer and you'd likely get corrected).

[jsjohnst]

I'm aware the misnaming was common, but it's a bad idea to do so. There's a pretty big difference between a T1 and a PRI in practice when used as a data only circuit. For one, the T-1 is a fair bit faster.