Non-VoIP numbers that pass SMS verification

Every North American phone number is registered against a carrier in a shared industry database. The record says which company holds the number and what kind of line it sits on: mobile, landline, or VoIP.

A non-VoIP number resolves to a mobile network operator, so a message to it travels the ordinary path — sender, aggregator, destination carrier, handset. A VoIP number resolves to an internet telephony provider instead. It can still receive texts, but its registration says where it came from, and anyone is free to look that up.

That single field is the whole distinction. It is not about how the number looks, how it was bought, or whether a real person answers it.

It runs a carrier lookup before it sends anything. Commercial lookup services return the carrier name and a line-type field — mobile, landline, voip — for a fraction of a cent per query, and a signup form calls one the moment you submit the number.

If the type comes back voip, the form refuses the number. You usually never see a "code sent" screen at all; you get "enter a valid phone number", which reads like a formatting error and is not one.

Some services go further and keep block lists of number ranges that have registered an unusual number of accounts. A number can be genuinely non-VoIP and still be turned away because of the company its neighbours keep.

VoIP numbers are cheap and effectively unlimited. Anyone willing to spend a little can hold thousands, which makes them the standard tool for bulk account creation, promotion farming and payment fraud.

Filtering on line type is the bluntest control that works, and the cost of a false positive is carried by the user, not the site. So it stays switched on even though it turns away plenty of legitimate people — travellers, people between carriers, and anyone who would rather not hand over a personal number.

If a service filters by line type, a VoIP number will not work however many times you retry, and no amount of reformatting changes the answer. What gets through is a number on a carrier network.

Every number in this catalogue is one. That is the product, and it is why it is priced per verification rather than per month: carrier-backed numbers cost real money to hold, and a pool of them is a running expense rather than a one-off purchase.

Worth knowing before you order, because none of these are fixed by trying again with a different number of the same kind:

• The service already has an account on that number. Numbers are recycled through the pool, and a service that allows one account per number will refuse a second.
• The service keeps its own range block list. Some of the largest ones do, and a range that has seen heavy signup traffic can be refused wholesale.
• The service requires a country we do not carry. A US number will not satisfy a form that insists on a local one.
• The message is late rather than blocked. Carrier queues back up, and a code can arrive after the site has expired it.

If no code arrives before the number expires, cancel the order and the charge comes back — you are not paying for a number that delivered nothing.