SIM swaps and the phone number

What you'll get from this chapter: How a criminal can take over your phone number, why that unlocks your accounts, and how to lock your number with your carrier.

Part II: Crypto Survival Kit · Chapter 5 of 9

Last reviewed: October 18, 2026

If your sign-in codes arrive by text message, those accounts are only as safe as your phone company’s process for moving your number to a new phone.

In a SIM swap, a criminal convinces your phone company to move your number to a SIM card (the small chip that ties a phone to a number) that they control. Their phone then receives your sign-in codes. Direct SIM-swap complaints to the FBI were under a thousand in 2025, with about $17 million lost. That is a severe undercount, because the theft that follows is usually filed as account takeover or investment fraud. Account-takeover losses ran into the hundreds of millions.¹

The warning sign is sudden silence: no bars, in a place that normally has service.

Some theft needs no phone call at all. The next chapter covers malware that quietly steals cryptocurrency from your computer.