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Canonical address format for phone numbers

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2, Windows Server 2008, Windows Server 2008 R2, Windows Server 8 Beta


Canonical address format for phone numbers

The canonical address format is a universal phone number format recognized by the Windows Server 2003 Telephony API (TAPI). The format explicitly identifies the components of a phone number, which TAPI translates according to a country or region's dialing rules. The canonical address format is:

**+**Country/RegionCode **(AreaCode)**SubscriberNumber

For example, this is how you would enter a number for a subscriber in the United States of America in canonical address format:

+1 (425) 555-0100

Some address book programs store numbers in canonical address format. If your computer is not dialing a number correctly, you may try saving or entering the number in this format.


  • +

    Indicates that the number is in canonical address format.

  • Country/RegionCode

    The standard country/region code that identifies the country or region for a phone number. This contains one or more digits from 0 through 9. The country/region code is delimited by the space that follows it.

  • (AreaCode)

    The area or city code for the phone number. This may contain one or more digits from 0 through 9. The area or city code is delimited by parentheses. This component is omitted for countries/regions that do not use area or city codes.

  • SubscriberNumber

    The number for a phone subscriber. This contains one or more digits from 0 to 9, formatting characters, or the dialing control characters:

  • A a B b C c D d P p T t W w * # ! @ $ ?

    The subscriber number should not contain the following characters:

  • ( ) ^

    Formatting characters in the subscriber numbers are normally spaces, periods, and dashes. Use formatting characters to make a phone number easier to read. They do not affect dialing, because TAPI discards them.