An object representing a phone number.
The phone number is recorded in 3 separate parts:
country_code - e.g. '385', '386'
area_code - e.g. '91', '47'
number - e.g. '5125486', '451588'
All parts are mandatory, but country code and area code can be set for all phone numbers using
Phone.default_country_code Phone.default_area_code