[megax]

An extender is designed to be used for making phone calls without directly billing the caller. Most mid-size and large companies that operated from multiple cities/countries used them.

Extenders connect to a PBX that is normally exposed via a toll free number (1-800), or a local number that allows the user to dial out to long distance numbers without incurring long distance connection charges.

It’s basically how prepaid long distance cards work nowadays: You dial a number, enter a code, get a dial tone, then dial your long distance number to connect.

[PaulHoule]

I grew up BBSing in Southern NH where you could not make a free call from Manchester to Nashua or Concord but it was a free call to towns in between those cities like Hooksett or Derry and a free call from those towns to adjoining cities.

One cheat we developed was a script that would make the BBS hang up, program the call forwarding, wait for a ring, then remove call forwarding. This way the caller could call a local BBS, choose a BBS in a distant city, hang up, dial again, then reach the second BBS.

It never really caught on for a few practical reasons, one was that somebody else could dial the first BBS when call forwarding was active and end up reaching the wrong BBS.

[megax]

That's a clever hack, which I wish I had known about.. and I love the unintended consequence of "BBS Roulette"