You are welcome. But where is the question?
You need to post the whole question in the correct forum if you expect a reasonable answer. Posting a question about phone number digits in a math forum will get you answers regarding digits as used in math.
US phone numbers have a country code of 1 followed by a 3-digit area code and a 7-digit local number. There are a total of 11 digits. There may be additional digits required in your phone system to access international dialing--perhaps an "exit code" of 0011. (See the source link.)