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Blog / Verification

Best Practices for Integrating Verification

24 Feb 2016 - 3 min read

Verified Success

We’ve given you some of the reasons verification is useful and becoming increasingly necessary, notably:

  • Phone numbers serve as a username with longevity
  • Reduce fraudulent or duplicate signups
  • Two factor authentication (require user to be in possession of a phone during signup)

Now, I wanted to share some best practices for integrating verification so that you experience a high success rate:

1. Number Formatting

Flash Call

Providers want numbers in e.164 format. All that means is a phone number with country code and no leading zeros. Many users won’t know the proper format of their international phone number, but luckily Sinch has a text helper method in our Verification SDK to clear up any confusion.

2. Provide a Fallback Method

In anything you do, it’s smart to have a backup plan. We always recommend a fallback options for SMS verification just to account for user error or a failed SMS. Voice Verification places a call asking the user to press a digit to confirm verification. If the digit is pressed, we notify your backend and the SDKs that the user is verified. For Android, we offer Flash Call verification, where we ask the user to do NOTHING and we can still verify them securely. In short, having one backup method for SMS will increase your success.

Verification Call

3. Give Users the Chance to Correct

Always display the phone number you are trying to verify. It’s easier than you may think to type in the wrong number, so displaying the number and showing a “back” button gives users the chance to correct the phone number and increases your chances of a successful verification.

4. Throttle Multiple Attempts

Without the throttle, a user may receive a number of SMS or calls making the verification process confusing and ineffective. Instead, limit verification tries to once every 30 seconds and a max of 3 attempts.

5. Clear Message Text

SMS Verification

Concise message text with a clear verification code will enable the user to enter their unique identifier without having to switch from your app to their SMS app to see the code. Instead, they can see the code drop down and enter it right then and there.


Follow these few simple best practices for integrating a verification solution and you’ll start seeing verification success rates go up while your users will enjoy the streamlined UX they’ve grown accustomed to in your app. If you have any questions about verification, please don’t hesitate to contact us.


Written by

Christian Jensen

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