The format for an endpoint is dependent on the country of the phone number.
If the endpoint is a United States mobile phone number, simply enter the phone number and the format will automatically update.
For example, if the endpoint is entered ‘2015550123’, the validation will update the number to ‘+1 (201) 555-0123’ once you have confirmed the step. You do not need to include, symbols or spacing when entering the endpoint. Also if you enter an endpoint in e164 format, the input will automatically select the correct country code for you.