A dial plan establishes the expected number and pattern of digits for a telephone number. This includes country codes, access codes, area codes and all combinations of digits dialed. For instance, the North American public switched telephone network (PSTN) uses a 10-digit dial plan that includes a 3-digit area code and a 7-digit telephone number. Most PBXs support variable-length dial plans that use 3 to 11 digits. Dial plans must comply with the telephone networks to which they connect.

In the U.S., some typical dial plans include:

• Internal extension numbers of two, three, or four digits.
• Local numbers of seven or ten digits, which may be preceded by a 9 if required to access an outside line.
• Long distance numbers of eleven digits, consisting of a 1, then a three-digit area code, then a seven-digit number; preceded by a 9 if required.
• International numbers of any length starting with 011 and preceded by a 9 if required.

[edit] Syntax

The following syntax used to identify a dial plan in a digit map is adapted from [RFC 2705]^{[page needed]}.

 To specify a  

 Enter the following 

 Result 

Some dial plan examples using the above syntax look as follows:

 For calls to 

 Users dial 

 Dial plan 

[edit] See also

• Uniform dialing plan
• Numbering plan