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Comment by oogali | Hacker News Reader

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

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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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