And further to that, throw in Local Number Portability (LNP) and you really need to know the full number in order to know which switch the specific number is assigned to. Not all 408-921 prefixed numbers will go to that switch in West San Jose.
Right, like I said three messages ago but that some people seem to have missed: NANP geographical numbers can be located to a switch (give or take number portability within a LATA),
A phone number, like an IP address, can only imply a physical location. It is not a guarantee, and that hint can range from moderately accurate to wildly wrong.
Quite right. US mobile carriers let you take your phone number anywhere in the country, so people do. There's also a fair amount of VoIP where again the phone need not be anywhere near the switch -- I have landline phone numbers in NYC, Santa Cruz, Monreal, and Cambridge UK, and don't live in any of those places. Bonus question: is there any way to find out whether and where a number's been ported without spending telco level amounts of money? Free would be nice. R's, John