Unable to use Person Phone Country Code in logic of delivered rule 'Validate Phone Number Format'

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University of Pittsburgh Medical Center (UPMC) - Delivered Autocomplete rule for validating phone number format

I am attempting to use the delivered ac rule 'Validate Phone Number Format' but unable to use the logic for phone country code as it appears we do not populate this information. Looking for the table of where this information is stored and what region this information is entered. Also looking for a recommendation on another field to use to capture the phone country. I was thinking of bringing in the person address country but the phone country could be different.