phone fun, was GeoIP database issues and the real world consequences

John Levine johnl at
Wed Apr 13 21:40:25 UTC 2016

>  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.


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