How to validate International phone number to disallow letters

Hi, my form needs to allow for users anywhere in the world to input their phone number, therefore, I cannot use the North American format which includes a numbers-only validation. Why does the International format allow letters? How can we disable letters and allow numbers and symbols only? I’ve read the closed threads on this topic and a masked text input solution does not work for this purpose because we don’t know how many digits international users will require.


The International phone format is … not great. The product team has an open issue to improve the handling of phone formats.

If you are trying to prevent the user from entering a letter in an international phone field, I don’t have a good solution for you. Gravity Forms does not handle front-end validation (as the user inputs), but that is also on our list of requested features.

You can use the gform_field_validation filter to review what the user submitted to you, and return a validation error if they used a character you do not want to allow.

Here is the documentation for gform_user_validation:

If you need assistance with the actual regex for the validation, let us know what symbols you want to allow, in addition to allowing digits. Thank you.

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