Retrieves the preferred country calling code for region_code
, e.g. 358 for "fi" or 1 for "en_USUTF
-8".
If null
is passed for region_code
the default region as returned by
phone_number_get_default_region is used.
region_code |
a two-letter country code, a locale name, or |
a valid country calling code, or zero if an unknown region code was passed. |