Can I set up Contacts phone numbers format
International Numbers 

To store international numbers in the Contacts app (without changing the whole phone in regional settings), you need to enter the country code when adding the number... and it will format it according to what is expected for that country.

Examples

Entering a standard US number, such as 3135551212 produces (313) 555-1212.

Entering the country code first, such as +13135551212 produces +1 (313) 555-1212.

For a Mexican phone number, entering +526241234567 produces +52 624 143 1234.

Etc... etc.    The trick is to use the plus symbol, plus the country code, in front of any international number.



Extensions

For extensions, the general rule is that you use a pause, or wait, in the phone number when you add it.   

For an extension number that you type immediately after dialing the number, use Pause. This adds a “,” to the phone number.

For a prolonged pause (like when the IVR goes on for a while before asking you to choose a number), use Wait and then key in the number.