Why so many job applicants use VOIP phone numbers

Post a remote engineering role and you may notice that a strange share of applicants list a phone number that, when you look it up, belongs to Bandwidth, Onvoy, Telnyx or another company you have never heard of. In one real pool of 1,455 applications to a single remote Frontend/AI Engineer posting, 60% of the numbers were in blocks held by VOIP wholesalers. This page explains what that means and what to do with it.

What a VOIP wholesaler is

Every North American phone number sits in a block of a thousand (the first seven digits), and every block is assigned to exactly one carrier by the North American Numbering Plan Administrator. Verizon, T-Mobile and AT&T hold blocks for their subscribers. A handful of carriers hold blocks for a different purpose: they sell numbers by API, instantly, in bulk, to the platforms that power VOIP apps, call centres and messaging services. Bandwidth, Onvoy and Inteliquent (both part of Sinch), Telnyx, Twilio, Peerless and Level 3 are the big ones.

A person who needs a throwaway number, or fifty of them, gets one from an app that buys from a wholesaler. That is why a wholesaler block is such a clean signal: real applicants almost never give one as their primary phone, and fraudulent applications almost always do, because the person behind them is running many identities and needs a number per identity.

Why fraud rings do this

Application fraud at scale, whether it is one person applying as many people, a proxy-interview operation, or an overseas worker applying under a borrowed identity, needs each identity to have its own contact details. Email addresses are free. Phone numbers are not, but a wholesaler number through a VOIP app is close to free and takes seconds. The number is real, it rings, it receives texts, and it looks ordinary until you check who holds its block.

What the signal is not

• Google Voice is different. Its blocks are held by Google, and plenty of real people use a Google Voice number for job applications precisely to keep their personal number private. ApplySift treats it as a weak signal.
• Ported numbers hide. A number ported from T-Mobile to a VOIP app keeps its T-Mobile block, and a number ported the other way keeps its wholesaler block. Porting records are private, so no free check can see them. In practice this is rare among applicants.
• It is one signal. A wholesaler number alone should put a candidate in a review pile, not a reject pile. Combined with a fresh Outlook address, a local part full of digits, or a phone shared with another applicant, it is close to conclusive.

How to check

One number at a time: the free number lookup on this site tells you the block holder from the public records. A whole file: export your applicants to CSV (guides per ATS), upload it, and see how many fall in wholesaler blocks, plus shared phones and mailboxes, throwaway addresses and the rest.