On Mon, Sep 20, 2010 at 11:08 AM, Peter Beckman <span dir="ltr"><<a href="mailto:beckman@angryox.com">beckman@angryox.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
In the past I've paid MelissaData.com $400 or so to get access to their<br>
NPANXX-Ratecenter-Location-GIS data. For each NPANXX, they list the<br>
Ratecenter, City and state/region, Lat/Lon coordinates. It's fairly<br>
accurate, though I'm not entirely sure how they get the data.<br></blockquote><div><br></div><div>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 (lat/lng).</div>
<div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Cloudvox's API is awesome (Thanks Cloudvox!), but outside of Country,<br>
Region and Ratecenter, the city and location data from their API has been<br>
somewhat wrong. Examples:<br></blockquote><div><br></div><div>You're very welcome.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<a href="http://digits.cloudvox.com/571/269/3" target="_blank">http://digits.cloudvox.com/571/269/3</a><br>
Ratecenter: WSNGTNZN17 VA<br>
City: WSNGTNZN08 (what?!?)<br>
Lat/Lon: 37.4315734, -78.6568942 (the center of Virginia, not even<br>
close to the DC area)<br>
<br>
<a href="http://digits.cloudvox.com/805/316" target="_blank">http://digits.cloudvox.com/805/316</a><br>
Ratecenter: SNLUSOBSPO CA<br>
City: SANBARBARA (Not a valid city name) </blockquote><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Lat/Lon: 36.778261, -119.4179324 (155 miles from San Luis Obispo, CA)<br></blockquote><div><br></div><div>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 :-)</div>
<div><br></div><div>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.</div><div><br>
</div><div>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.</div>
<div><br></div><div>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).</div>
<div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">There are others, but I won't bore you. To give them credit, they have a<br>
"geo_precision" which I assume tells you how many significant digits you<br>
can trust, but is not mentioned in the API docs<br>
( <a href="http://help.cloudvox.com/faqs/digits/digits-phone-number-location-lookup-api" target="_blank">http://help.cloudvox.com/faqs/digits/digits-phone-number-location-lookup-api</a> )<br></blockquote><div> </div>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.</div>
<div class="gmail_quote"><br></div><div class="gmail_quote">Cheers,</div><div class="gmail_quote"><br></div><div class="gmail_quote">Troy</div><div class="gmail_quote"><a href="http://twitter.com/troyd">http://twitter.com/troyd</a></div>