• From abroad: dial +43 (or your country's exit code, e.g. 00 from Europe, 011 from North America), then the national number without the leading 0. Example: +43 664 123456
  • Within Austria: dial the number as written domestically, including the trunk prefix 0. Example: 0664 123456
  • Calling abroad from Austria: the international prefix is 00, or simply use + on mobiles.
  • Storing numbers in software: always store E.164 (+43664123456): unambiguous, sortable, and what SMS and telephony APIs expect.