I always wondered, could the phone companies one day get motivated and make every phone in America ring at once? Maybe someone who works/worked for the telecoms knows, heck, maybe someone even manned the “Call Everyone” button.
Thanks in advance to the millions.
Brent
Well, times in the past when “everyone” tried to call at once, the circuits jammed totally and nobody could get through at all. I’m thinking specifically of the 1989 Loma Prieta earthquake out in California, and also, of course, following the WTC bombings. Both land lines and cell phones were jammed, IIRC, just from sheer volume.
If you “called everyone”, it would jam up everything, so no, I doubt whether the phone company would even have such a function.
Although having all the phones ring simultaneously in your house seems to be a staple of the “He Knows You’re Alone” horror genre… 
not to mention stephen king
Probably can’t be done.
The ringer goes off when your phone receives a voltage spike from your local Central Office. The COs are connected to each other and to Long Distance carriers via (mostly fiber) cables. So every single CO in every single town would have to cooperate.
But, there are more customer loops (physical circuits from the CO to the customer’s house) than there is switching capacity, because only a small percentage of telephones are in use at a given time. When you pick up your phone to make a call, the equipment on the other end senses the voltage change and connects you to an idle channel in the switching machine. Similarly, when someone calls you, an idle channel at your CO’s switching machine must connect to your line and zap it to make the phones ring. If everyone picks up their phones at once, which happens sometimes during emergencies/disasters/invasions from outer space, most people won’t even get a dialtone.
Also, there’s the issue of PBXs. Say the telco rings all the incoming lines two a PBX, how does the PBX switch know to ring every phone connected to it?
No.
Based on the fact that there is not enough switching capacity.
This is based on the expectation that only x number of switches are available for n number of physical phones where x < n.
Telco Guy.
The above posts are talking about oversubscription, also called overbooking. In my footprint (the US Northeast) we are permitted by the FCC to over oversubscribe our facilities to the tune of 300%, and then we cross our fingers and hope that all of those circuits don’t get used simultaneously. Occasionally it happens, and you’ll usually get a fast busy signal, indicating no trunks are available to route your call.
To the OP, circuits are tested manually with software developed by Hekimian Laboratories for use exclusively by ILECs. There is no feature that will allow me to ring up more than one circuit at a time, but I’m sure a script could be written to put multiple circuits into simultaneous test if it were all that important. But with the current testing interface, nope.