nanog mailing list archives

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


From: Owen DeLong <owen () delong com>
Date: Wed, 13 Apr 2016 12:25:23 -0700


On Apr 13, 2016, at 12:15 , John Levine <johnl () iecc com> wrote:

Actually, it's probably both US and Canadian.  When you call an 8xx
toll free number, the switch uses a database to route the call to
whatever carrier handles it, who can then do whatever they want.  The
provider for that number, Callture, is in Ontario but they can
terminate the calls anywhere, and send each call to a different place.

I was careful to pick a number on a Canadian company's website.

Doesn't matter.  In the NANP, toll free 8xx numbers are routed by
carrier, not by geography, and it looks like this company handles
traffic in the US, too.  It's entirely possible that when you call
that number during the day you get someone in Toronto, and when you
call it at night, you get an answering service in the Phillipines.

Also, in fairness, the US is about 90% of the NANP, so guessing that
an 8XX number is in the US is usually correct.

That's another way of saying that it's deliberately wrong 10% of the
time for pan-NANP prefixes. Better to say "I don't know" than to just
guess.

Really, they're not assigned to locations, they're assigned to
carriers.  They can even be assigned to different carriers in
different countries although that's not common.

More to the point, saying "somewhere in the US", even if it's
occasionally wrong, will not send nitwits with guns to a particular
location.  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?

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.

I will also guarantee you that those phones move locations quite frequently.

Owen


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