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Comment by oogali | Hacker News Reader

The authoritative database is owned by Neustar[1] and is non-public.

There are entities that subscribe to the service and fulfill those queries (such as unlec.com or whatever reseller they're getting the information via).

But the Neustar revenue model is to charge per query which is why that site limits the number of queries one can perform.

Every time you place a phone call in US or Canada, the originating carrier does a lookup against the Neustar-NPAC database (also called a "dip") to determine the routing destination for your call.

Only after that response (called a "LRN" or location routing number) is received does call routing truly begin.

1: https://www.npac.com/canadian-number-portability/the-npac-ne...

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> Every time you place a phone call in US or Canada, the originating carrier does a lookup against the Neustar-NPAC database (also called a "dip") to determine the routing destination for your call.

Is this able to determine if the phone is connected through wifi calling? (There was a discussion yesterday where some one suggested SMS may not be sent to a phone connected to wifi only if the sender did not wish to but I could not see a mechanism that would allow that determination.)

There is a separate field called OLI, originating line indicator, that indicates whether landline, cellular or other. From memory, it's 0 for landline and 62 or 63 for cellular.

I doubt you can reliably determine if on Wifi or not, although of course the carrier handling that phone would know.

They're likely referring to the data that comes out of LIDB[1] which is not a real-time indicator. Instead, it's what the carrier has stored against that phone number.

The LIDB data will consist of a field that marks that phone number as a landline, broadband (aka VoIP), cellular, etc.

There are some 2FA implementations you come across will look up whether a number you're trying to enroll is classified as anything other than cellular, and if so, it gets rejected.

1: https://en.wikipedia.org/wiki/Line_information_database

Thanks for the clarification. That is what I thought as well. I've heard of people being able to use Google Voice or other VoIP from 2FA even when it would normally be rejected by using a cellular number that they then port to Google Voice.

Based on what I've read, some video games are able to determine if you're using a prepaid plan or post paid. I suppose they might just look up the carrier to determine that since it doesn't seem like that level of granularity is available. And the port trick may work there as well.

My work number is a Google voice number, but was my 'real' number before segmentation in hopes of gaining sanity with my phone (sidenote, if anyone is self employed and busy enough to be debating such a plan, do it, no regrets), and I've had zero issues with 2FA coming through to my once a cell number now a voice number.

Mostly, but not every time.

I also have a Google Voice-backed number (since before Google acquisition, when it was Grand Central), and every now and then I find a site that doesn't accept GV numbers for 2FA. A recent example was Simplisafe.

Does anyone know where "Fraud Risk" and "Textable" come from in unlec's database? My number has fraud risk = high, and textable = No -- even though text works just fine via GV, and it's a personal number with minimal use, so no reason for flag (other than some companies not liking virtual carriers).

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