How to Prevent SIM Swap Attacks on Your Crypto Accounts

Preventing a SIM swap attack means removing your phone number as a usable attack surface: locking it against unauthorized transfers with your carrier, replacing SMS-based two-factor authentication with app-based or hardware alternatives everywhere possible, and limiting how much personal and financial information is publicly connected to your identity.

If you're unfamiliar with how these attacks work, our companion piece on what a SIM swap attack is covers the mechanics. This guide focuses on concrete preventive steps.

Step 1: Set a carrier PIN or port-freeze

Every major mobile carrier offers some form of additional security for account changes — often called a port-out PIN, transfer PIN, or account passcode — that must be provided before a phone number can be transferred to a new SIM or carrier. Call your carrier directly (not through a link in a text or email) and:

• Set a unique PIN that is not your birth date, a repeated digit sequence, or otherwise guessable from public information.
• Ask specifically whether a port freeze or number lock is available, which blocks transfers entirely until manually lifted by you, in person if the carrier supports it — this is stronger than a PIN alone.
• Confirm the PIN is actually required for phone-based support requests too, not just online account changes, since attackers often target phone support specifically to socially engineer around digital protections.

Step 2: Remove SMS as your 2FA method wherever possible

Go through every account tied to your phone number — email, exchanges, and any platform holding funds — and switch two-factor authentication from SMS to an authenticator app (using the TOTP standard) or, ideally, a hardware security key. This is the single highest-impact step, because even a successful SIM swap becomes useless against an account with no SMS dependency at all. See our comparisons of authenticator apps vs. SMS 2FA and hardware keys vs. authenticator apps to choose the right option for each account, and our step-by-step 2FA setup guide if you need a walkthrough.

Step 3: Reduce your public information footprint

SIM swap attackers typically research targets using publicly available information — social media posts, data breach leaks, and even details shared in seemingly unrelated contexts. Avoid publicly disclosing crypto holdings, portfolio size, or notable trading activity, since this visibility is what makes someone a worthwhile target for a labor-intensive attack in the first place. This ties directly into the broader practice of wallet OPSEC — treating your financial information as need-to-know, not public.

Step 4: Separate your recovery methods

Avoid using the same phone number as the recovery method for both your email and your exchange accounts — if a single hijacked number can reset both, an attacker only needs to succeed once. Where possible, use an email address dedicated to financial accounts that isn't linked to your primary, publicly known email or phone number, and secure that email account itself with strong, non-SMS 2FA.

Step 5: Monitor for early warning signs

Set a habit of treating sudden, unexplained loss of cell signal as a potential SIM swap in progress rather than a routine outage, especially if it coincides with unexpected account notifications. If this happens, contact your carrier through an alternate method (a different phone, a computer) immediately, and simultaneously check your most important accounts (primary email first, since it usually gates everything else) for signs of unauthorized password reset attempts.

Prevention steps by effort and impact

Step	Effort	Impact
Carrier PIN / port-freeze	Low (one call)	High — blocks the transfer itself
Replace SMS 2FA with app/hardware	Medium (per-account setup)	Very high — removes the dependency entirely
Reduce public info footprint	Ongoing habit	Medium — reduces likelihood of being targeted
Separate recovery emails	Low-medium (one-time setup)	Medium — limits blast radius of any single hijack
Monitor for signal loss / reset alerts	Ongoing awareness	High — enables fast response if it happens anyway

If an attack succeeds anyway

Contact your carrier immediately through an alternate channel to reverse the unauthorized port and regain your number. Change passwords on all critical accounts from a secure device, starting with your primary email, since regaining control there lets you lock down everything downstream. Enable non-SMS 2FA on every account as you regain access, so the same vulnerability can't be exploited again. If crypto exchange accounts were compromised, contact the exchange's support immediately to freeze withdrawals, and review our broader DeFi wallet security guide for hardening self-custodied assets going forward, since a hardware wallet held offline is unaffected by any account-level compromise.

Bottom line

A SIM swap attack depends entirely on your phone number being both transferable and useful to an attacker — a carrier port-freeze addresses the first problem, and removing SMS-based 2FA from your important accounts addresses the second. Doing both takes under an hour of setup and eliminates one of the more dangerous, and preventable, attack paths against crypto holders specifically.