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.

Syntax

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

{| width="75%" cellspacing="1" cellpadding="1" style="background-color: #efefef; border: solid 1px #eeeeee;"
     |+ Dial Plan Syntax
     |-
     ! 
To specify a 
     ! 
Enter the following
     ! 
Result
     |-
     | Digit
     | 0 1 2 3 4 5 6 7 8 9 *
     | Identifies a specific digit (do not use #)
     |-
     | Range
     | [digit-digit]
     | Identifies any digit dialed that is included in the range
     |-
     | Range
     | [digit-digit, digit]
     | Specifies a range as a comma separated list
     |-
     | Wildcard
     | x
     | x matches any single digit that is dialed
     |-
     | Wildcard
     | .
     | . matches an arbitrary number of digits
     |-
     | Timer
     | T
     | Indicates that an additional time out period of 4 seconds should take place before automatic dialing starts
     |-
     |}

Some dial plan examples using the above syntax look as follows: {| width="75%" cellspacing="1" cellpadding="1" style="background-color: #efefef; border: solid 1px #eeeeee;" |+ Dial Plan Syntax Examples |- ! For calls to ! Users dial ! Dial plan |- | Internal Extension |

See also

• Uniform dialing plan
• Numbering plan

ro:Plan de numerotare