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Originally Posted by baddog
Well, I am not going to speak on behalf of cellular technology, but it is common knowledge that with landlines the ratio of phones to available circuits required to draw dial tone is pretty high . . . like 1:50 . . . possibly higher (it has been a while since I was trained on that basic stuff).
Essentially, it means that whenever there is a catastrophe (ie: earthquake, bombing) and too many people reach for their phones at once, it will simply lock up the system, because as everyone knows, the computer's first responsibility is to itself. Getting you dial tone is simply a perk made available as long as the switch can handle its own functions.
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B.D. is correct. After 8 years in telco, the reason there is a problem with there is an emergency is because of the ratio. Obviously there is little real chance that everyone in a town will be on the phone at the same time, hence there is not 100,000 copper loops, or pairs for a town of 100,000. Like B.D. I can't recall the ratio, but I believe it's even higher that the 1:50. I wanna say it's in the hundreds, but I could be mistaken.
Anyways, it works on the same philosophy as a business. Big business (unless a call center, or something like that), depending on phone usage is anywhere from a 1:5, or 1:24 ratio. Meaning one phone line per 5 phone users. This is where people get into taking a 24 channel voice T1, or PRI and splitting off channels, and how they manage their telco services.
When you call a big company, and you can't get through, a lot of times they either they do not have their phone system/routers in the correct configuration for their usage, or they are out of trunks. A lot of time they will need to add in another PRI/T1 all depending.
Anyways, back on topic. If the city had 100,000 households, I've guess their central office would have maybe 25,000 trunks. Depending on how the network's configured (on number of T1's, PRi's, ig biz, etc versus 1 line users) all will have an effect. If the town's hit by something that gets more than the law of average's picking up phones, then you get the switch is busy, or whatever that error message is.
Telco does everything on the laws of numbers, and track things. So they base trunks, by average call times, volumes, and so forth. Average call is 4 minutes, and if there are more of them for longer, it fucks up the network of averages.
I would assume a cellular network is set up on some similar predication as well for network management, but my background's in land line telco.
