conference call - NicheInterests/mistfunk GitHub Wiki

Today, we have the group text. 80 years ago, we had the party line. In between, there was the conference call: mostly used by corporations to hold voice meetings with traveling staff or remote offices, a conference call allowed a (potentially large) number of telephone callers to (for a fee, paid by the host) participate in a group conversation -- though realistically you would only hear one speaker at a time, and often would have no idea who said speaker was.

Conference call services were of little use to home telephone customers, but as part of the extended suite of [telephony] services they proved to be of interest to [phreak]s, who would sometimes show off to their elite buddies by gathering an audience and then making prank phone calls to pizzarias and video rental outlets in the vein of celebrity phone pranksters the Jerky Boys.

https://lareviewofbooks.org/article/the-invisible-playground-phone-phreaking-and-the-criminalization-of-curiosity/ includes reference to a Vancouver connection to a famous and influential phreaking conference call in 1970.