Dialing format settings are available in Telephony 2.0 >> Settings.

E164 format

The "International Public Telecommunication Numbering Plan" (E.164), an international standard (ITU-T Recommendation), specifies the numbering scheme for the global public switched telephone network (PSTN) and a few other data networks.

The B-side device often starts the display of the number with a plus sign (+), indicating that the number includes a country code. In general, the prefix of the matching international call must come before the number when dialing it (instead of a plus sign).

The ITU states that the standard E.164 format should only contain digits split as follows:

  • Country code (1 to 3 digits)

  • Subscriber number (maximum 12 digits)

  • Alternate formats are available (with area codes and country-specific numbers).

The name of the original version and first revision of the E.164 standard was "Numbering Plan for the ISDN Era".