You are probably thinking of the WATS pins. It was a huge thing at the time to war dial entire exchanges to find them, and then publish the lists. A lot of the time people would then use unsecured bridges to hold mass group chats. Beto was no stranger to those circles, even though cDc actively stated the level of risk one takes on when doing so.

Bridges were terrible for modems, as at any moment another war dialer would connect, or people looking to chat, and knock the modem offline from the announce beep.

The chats were mainly social, but a lot of technical discourse occurred, which was a huge draw.