Why is my country code defaulting to +1 when I add a number to a user profile?
The Zendesk Support interface and Twilio backend design defaults the country code to US country code +1 if your phone number is nine digits. This leads Twilio to read the number as US number by default.
Phone numbers should be formatted with a '+' and country code e.g., +16175551212 (E.164 format). Twilio will also accept unformatted US numbers e.g., (415) 555-1212 or 415-555-1212
To view the latest regarding number validation, check out this announcement on number validation.