Getting Started
25
Regular expression, often called a pattern, is an expression that specifies a set of strings.
A regular expression provides a concise and flexible means to "match" (specify and
recognize) strings of text, such as particular characters, words, or patterns of characters.
Regular expression is used by many text editors, utilities, and programming languages
to search and manipulate text based on patterns.
Regular expression can be used to define dial plan for the IP phones. Dial plan is a
string of characters that governs the way for the IP phones processing the inputs
received from the IP phone keypads. The IP phones support the following dial plan
features:
Replace Rule
Dial-now
Area Code
Block Out
The priority of matching dial plan is: Dial Now>Replace Rule>Area Code>Block Out.
You need to know the following basic regular expression syntax when creating dial
plan:
The dot ―.‖ can be used as a placeholder or multiple placeholders for
any string. Example:
―12.‖ would match ―123‖, ―1234‖, ―12345‖, ―12abc‖, etc.
The ―x‖ can be used as a placeholder for any character. Example:
―12x‖ would match ―121‖, ―122‖, ―123‖, ―12a‖, etc.
The dash ―-‖ can be used to match a range of characters within the
brackets. Example:
―[5-7]‖ would match the number ―5‖, ‖6‖ or ‖7‖.
The comma ―,‖ can be used as a separator within the bracket.
Example:
―[2,5,8]‖ would match the number ‖2‖, ―5‖ or ―8‖.
The square bracket "[]" can be used as a placeholder for a single
character which matches any of a set of characters. Example:
"91[5-7]1234"would match ―9151234‖, ―9161234‖, ―9171234‖.
The parenthesis "( )" can be used to group together patterns, for
instance, to logically combine two or more patterns. Example:
"([1-9])([2-7])3" would match ―923‖, ―153‖, ―673‖, etc.
The ―$‖ followed by the sequence number of a parenthesis means
the characters placed in the parenthesis. The sequence number
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