Number verification is a mobile network API that confirms whether the device making a request is using the SIM registered to a given phone number, without sending the user a code.
Field guide
Inventory every flow that sends a code, write the risk assessment NIST SP 800-63B-4 asks for, fix account recovery and new-payee setup first, then move customers to phishing-resistant or device-bound methods such as passkeys and in-app approval. Keep SMS only as a restricted fallback, with a dated plan to remove it.
Field guide
Treat the account as compromised until proven otherwise: stop trusting the phone number, revoke sessions, hold new payees and contact-detail changes, and reach the customer through a channel that isn’t the hijacked number. Then help them reclaim the number from their carrier, review everything that changed during the exposure window, and re-enroll them with a method that doesn’t depend on SMS.
Buyer’s guide
The most direct signal comes from the mobile operator: a SIM swap check reports whether the SIM tied to a number changed recently, and number verification confirms a request comes from that SIM. The CAMARA project standardizes both APIs. Banks combine them with their own device and session signals, and use them before trusting a number for recovery, new payees or high-risk payments.
Buyer’s guide
There is no single best alternative for every flow. Passkeys are the most widely standardized phishing-resistant option and are accepted by NIST at AAL2. In-app approval on a registered device is what UAE and Singapore banks moved customers to. Carrier network checks are useful risk signals, and SIM-based cryptographic methods are emerging. Most organizations combine two or more.
Vendor brief
Glide Identity(owner interest: see disclosure), a US company that trades as Glide.id, says its MagicalAuth product replaces SMS codes with verification through the mobile network, and in August 2026 it announced a beta across AT&T, T-Mobile and Verizon. Before a pilot, get written answers on how the method would be classified under NIST SP 800-63B-4, when and how fallback triggers, which devices, operating systems and plans are covered, how SIM swaps and eSIM transfers are handled, what data is processed, what it costs and how you would leave. We found no independent security assessment in our sources.
Explainer
Carrier-based authentication verifies a user through their mobile operator instead of sending them a code. The simplest form checks that a request comes from the SIM tied to a phone number; stronger forms use cryptographic keys held in the SIM to sign the request.