Guides & tutorials

The complete guide on phone OTP verification flows

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Looking for an easy way to verify phone numbers? Build custom OTP flows with our fully editable templates. Easily edit steps, fields, texts and CSS styles, plus connect any service with an API at any stage of the form, even between form steps.

​​Why start using phone OTP verification?

Sending temporary codes or one-time passwords is a common and especially useful solution in different scenarios:

  • Multi-factor authentication. Verify the identity of your new users in signup processes, by checking that the phone number provided really belongs to them.
  • Passwordless login. It allows registered users to open their session without having to remember a password, sending them a temporary code when they want to log in.
  • Lead qualification. Verify that the phone number provided belongs to the lead, before adding the contact to your marketing and sales database.
  • Coupon campaigns. Prevent fraud when launching coupon campaigns, to ensure that the same person cannot use different accounts to benefit from a discount.

Twilio: Sending temporary codes by SMS

To verify users by sending OTPs by SMS you will only need to customize this template and connect it with your Twilio account by pasting a few data.

It consists of a form with 2 steps and 2 flows with custom logic. The first step of the form will ask for a phone number and, the second one, for the code sent to it.

In the backend, a flow will generate and send the OTP after the user inputs the phone number, and a second flow will validate it after inputting it in the form.

All the templates are fully editable. So you can add more steps, texts, fields, flows with custom logic and integrations, and even modify its design

If you prefer, you can build it from scratch, using the forms and flows editor

WhatsApp: How to send OTPs by message

Do you prefer to verify phone numbers via WhatsApp? Just edit the template in your editor and fully personalize its design. Plus you can add more steps, fields, integrations, etc.

To configure this action, you will only need to configure an app in yourFacebook Business Manager and paste a couple of data in the action settings.

Of course, if you prefer, you can build it from scratch and learn here how to build the JSON object to include in the message field.

Telegram: Chatbot OTP phone verification

Creating an OTP flow with Telegram is easier than you may think. All you need to do is configure a Telegram bot and then configure the template by pasting a few data.

Arengu allows you to create any form and flows you can think of, by easily integrating any service with an API to build advanced and completely custom use cases.

Bonus tip: Voice OTP with Twilio

Trigger automatic phone calls to verify mobile and landline numbers, with the 'Make call with Twilio' action. For example, you can use it to verify your uses by sending voice OTPs.

To use this action, you just need to connect your account and build the message in XML format. Of course, you can include variables in it.

Need help when building your use case? Book a demo with one of our experts to see how to configure it and adapt it to the needs of your business.

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Getting started with Arengu

Arengu allows you to build all your user flows connected to your current stack, and avoids coding all the UI, complex integrations, validations or logic from scratch. Try it for free and start building faster and scaling your application needs as they grow.