PhoneAndAreaCode 

A phone number field with a selectable international area code. The field renders a select box containing all international dial codes (e.g. +49) next to a text field for the phone number itself.

The list of area codes is loaded from EXT:lia_form/Configuration/Data/PhoneAreaCodeList.json. Each entry consists of a country name, the dial code and the ISO country code:

{
  "name": "Germany",
  "dial_code": "+49",
  "code": "DE"
}

To use a custom data source, subscribe to the BeforePhoneAreaCodeInitializeEvent and set your own path to a JSON file with the same structure.