United Kingdom Mobile Numbers Being Rejected as Invalid

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1

Hi Auth0 community,

We’re encountering an issue where a subset of users in the United Kingdom have their mobile phone numbers incorrectly flagged as invalid, despite the fact that UK mobile number signups are generally working and successful for the majority of users.

Due to privacy constraints, I can’t share the actual phone numbers here. However, we’ve validated the affected numbers using Google’s libphonenumber library ( GitHub - google/libphonenumber: Google's common Java, C++ and JavaScript library for parsing, formatting, and validating international phone numbers. · GitHub ), and they are all recognized as valid UK mobile numbers capable of receiving SMS.

Steps to reproduce:

  1. The user resets their password using the provided link.
  2. The user logs in using their provisioned email address and new password.
  3. The user is prompted to enter a mobile phone number.
  4. The user selects United Kingdom (GB +44) as the country.
  5. The user enters their mobile number, but the application reports it as invalid and suggests the number is incorrect.

Our support team has occasionally been able to work around the issue by instructing users to omit the trunk prefix (0) when entering their phone number.

Are there any recommended mitigation steps or configuration changes we can apply to prevent valid UK mobile numbers from being rejected in this scenario?

3

Hi @lance.becker

Welcome to the Auth0 Community!

Have you added the phone number as a primary attribute to the user database that you are using or do you want to add it to their profile prior to them signing up?

Also, can you provide some examples of phone number which receive that error?

Usually, the prefix is not needed for phone numbers so it would make sense why trunkating it works as intended.

Looking forward to your answer.

Kind Regards,
Nik

4

Hello Nik,

This error is occurring when the phone number is being validated client side during the Passwordless / SMS flow. Manually I could enter this number in the dashboard with no issue.

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