[VoiceOps] Rate Center Maps, Locations for NPANXXs

Troy Davis troy at yort.com
Mon Sep 20 21:49:53 EDT 2010

On Mon, Sep 20, 2010 at 11:08 AM, Peter Beckman <beckman at angryox.com> wrote:

> In the past I've paid MelissaData.com $400 or so to get access to their
> NPANXX-Ratecenter-Location-GIS data.  For each NPANXX, they list the
> Ratecenter, City and state/region, Lat/Lon coordinates.  It's fairly
> accurate, though I'm not entirely sure how they get the data.

We ran the ratecenter through Google's geocoder, in some cases with a bit
ofB preprocessing and/or filters (state/county where known).  But it's very
much a best guess.  Our goal with Digits has been to expose everything we
can provide for free. Sometimes that's quite reliable (rate center), some of
which is mostly accurate (carrier, city), and some of which is a crapshoot

Cloudvox's API is awesome (Thanks Cloudvox!), but outside of Country,
> Region and Ratecenter, the city and location data from their API has been
> somewhat wrong.  Examples:

You're very welcome.

>    http://digits.cloudvox.com/571/269/3
>    Ratecenter: WSNGTNZN17 VA
>    City: WSNGTNZN08 (what?!?)
>    Lat/Lon: 37.4315734, -78.6568942 (the center of Virginia, not even
>    close to the DC area)
>    http://digits.cloudvox.com/805/316
>    Ratecenter: SNLUSOBSPO CA
>    City: SANBARBARA (Not a valid city name)

   Lat/Lon: 36.778261, -119.4179324 (155 miles from San Luis Obispo, CA)

Those are cases of garbage in, garbage out.  We start with mediocre data
(ratecenter string like "WSNGTNZN17") and run with it as far as possible.
 Some ("SEATTLE") are easier than others :-)

I'd definitely consider replacing these lat/lng values with the CO lat/lng
if you're able to find an unencumbered copy.  I think you're right that they
would be more accurate.

As far as current accuracy, it depends on what you want to do with the data.
 It's completely unsuitable for making call routing or rating decisions.
 It's ideal for customizing/localizing IVRs, displaying inline maps,
analyzing CDRs, deciding whether to offer a SMS menu choice, data appending,
and the like, because all of those depend on depth of data and flexibility
more than accuracy.

Regarding John Todd's note that wireless users and VoIP carriers have
decoupled number from location, a byproduct is that for non-routing uses,
that makes Digits about as accurate as anything else -- not because Digits
is dead on, but because nothing else is anymore either.  Digits might be 50
miles off, but there's a good chance that a wireless subscriber is 50 miles
from their area code center anyway, so the API consumer already expects
imprecision (except for routing).

There are others, but I won't bore you.  To give them credit, they have a
> "geo_precision" which I assume tells you how many significant digits you
> can trust, but is not mentioned in the API docs
> (
> http://help.cloudvox.com/faqs/digits/digits-phone-number-location-lookup-api)

Good catch, and thanks for the heads up.  I just added geo_precision to the
docs and examples, and clarified its meaning and where lat/lng come from.


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