Verification codes your customers actually receive

An OTP (one-time password) is a single-use code sent to a user to confirm their identity.

Two-factor authentication (2FA) uses two different forms of evidence to confirm identity.

An OTP is commonly used as the second factor alongside a password, but it can also be used in other verification flows.

It depends on where your users are. SMS works almost everywhere and is the standard default.

WhatsApp, Viber, and Telegram often deliver better in markets with heavy SMS filtering, and flash call is the cheapest at high volume.

With Dexatel you don't have to choose one: set a fallback order and the verification API works down the list.

If a code fails on the primary channel, Dexatel resends it on the next channel in your configured sequence, for example SMS, then WhatsApp, then Viber. This raises verification success rates without any extra work in your application.

Yes. Dexatel is ISO 27001 certified and GDPR compliant, and European data stays in the EU. Codes are one-time and short-lived, and delivery data is handled under GDPR-aligned retention rules.

Dexatel also complies with other international regulations such as TCPA, HIPAA, and PSD2.

Yes. Sign up for a free trial and your account comes with trial credit to send real verifications, real codes, to real phones, across the channels you want to try. What you see in the trial is exactly what your users will get.

Dexatel validates numbers in real time before sending, so codes never go to fake or premium-rate numbers triggered by bots.

That stops SMS-pumping fraud before it reaches your invoice.

For deeper protection, Dexatel Lookup returns each number's validity, line type, carrier, country, and whether it's been ported.