How to return Numeric value ONLY for Phone Number field using Autocomplete

Summary:

How to return numeric value ONLY for Phone Number field using Autocomplete

Content (required):

We are using the delivered 'Validate Phone Number Format' from Business Object - Person Phone, and we need to have error message if the value entered is not Numeric. How to define variables to achieve this? Please advise.

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23B

Code Snippet (add any code snippets that support your topic, if applicable):