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

John Levine johnl at
Wed Apr 13 21:52:23 UTC 2016

>Is there the equivalent of BGP for number portability where every telco
>has the full table of who owns each prefix as well as individual routes
>for ported numbers ?

Not really.  There's a switch database used for routing calls, but
that's different from LNP which is a layer sort of above that.

>Or is there a central database that is consulted before a dialed number
>starts to be connected so originating telco knows to send call ?

Often, if the switch can't tell that the number hasn't been ported.

>Or does the originating telco route the call to the original onwer of
>the prefix and lets that original owner figure out how to terminate the
>call ?

That's called Onward Routing.  They do it some places but not in North
America.  See RFC 3482 for a well written overview of number portability.

>From a long distance billing point of view, if Bell Canada connects to a
>number originally onwed by AT&T but ported to Verizon, with whom would
>Bell share long distance revenues ?

They pay whatever long distance company they use, and that company
pays the owner of the switch to which it's delivered.  The long
distance company also pays a very small amount to Telcordia which runs
the LNP database to tell whether the number's been ported and if so to
which switch.


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