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

Peter Beckman beckman at
Wed Apr 13 20:18:34 UTC 2016

On Wed, 13 Apr 2016, John R. Levine wrote:

>>> NANP geographical numbers can be located to a switch (give
>>> or take number portability within a LATA), but non-geographic numbers
>>> can really go anywhere.  On the third hand, it's still true that the
>>> large majority of them are in the U.S.
>> Would you agree that 408-921 is a geographic number?
> No.  It's a prefix, assigned to the at&t switch in west San Jose.

  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.

>> I guarantee you that there are phones within that prefix within 
>> US/Calif/LATA-1 and also some well outside of that, probably not even in 
>> the same country.
> Who said anything about phones?  Could you describe what "geographic numbers 
> can be located to a switch" means to you?

  In the same way that an IP address and it's "location" is amorphous, the
  physical location in which a phone call to a given phone number is
  answered could be anywhere. There could be a forward on it that sends a
  call made to US number +1 408-192-4135[1] to a phone in Latvia. Or it
  rings to a computer in London, which forwards it to Brussels.

  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.


[1] Intentionally invalid NANPA, for example purposes only
Peter Beckman                                                  Internet Guy
beckman at                       

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