Microsoft telephone number format

Microsoft canonical address format for telephone numbers^[1] defines a universal formatting recognized by the Windows Server Telephony API (TAPI).

This format derives from the E.123 format by authorizing the embedding of the area codes, delimited by parentheses, inside the E.123 international format.

This flexible addition to the E.123 international format makes the Microsoft format the de facto standard used to display telephone numbers that can be easily understood both by national and internal users.

Microsoft canonical format description

The canonical address format is: +Country/RegionCode (AreaCode) SubscriberNumber and is formed with the following components and rules:

• The leading plus (+) indicates the beginning of a canonical telephone address format.
• The country or region code which contains one or more digits from 0 through 9.
• A space must be used after the country or region code.
• Parentheses are delimiting the optional area code which contains one or more digits from 0 through 9.
• A space must be used after the area code.
• The subscriber number 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 * # ! @ $ ?.
• Formatting characters allowed to make the subscriber number easier to read are spaces, periods, and dashes.

Format comparison with E.123

E.123 telephone number, national notation	[phone]
E.123 telephone number, international notation	[phone]
Microsoft telephone number format	[phone]

• As in E.123, Microsoft format recommends that only spaces be used to visually separate groups of numbers.
• Contrary to E.123, in Microsoft format parentheses are used to indicate the area code digits that are sometimes not dialled. Whereas in E.123, parentheses are not allowed in the international notation, according to the standard.
• Contrary to E.123, Microsoft format allows periods, dashes, and not only spaces to separate number groups.
• Contrary to E.123, Microsoft format does not allow the use of a slash (/) with spaces to indicate alternative numbers.

References

1. Microsoft Technet: Canonical address format for phone numbers

See also

• E.123
• Local conventions for writing telephone numbers