Auto Format Phone Numbers Based on Your Location or Country Code
When you edit your contacts’ phone numbers, these will automatically be formatted for your country (set in your preferences) or according to the country code of the phone number.
Your phone number locale can be set in the preferences dialog.
For example, you’ve set your locale to the United States and enter a phone number. When you click out of the field, the phone number will be automatically formatted as follows:
Turn Off Automatic Phone Format
If you don’t want to apply the automatic phone format, you can turn it off. Go to Administrator module > Preferences > System Options and uncheck “Automatically format phone numbers to my locale”.