AudioCodes Mediant 4000 SBC User Manual page 496

CHAPTER 20 SIP Definitions
The Dial Plan itself is a set of dial plan rules having the following attributes:
■ Prefix: The prefix is matched against the source and/or destination number of the incoming call
(e.g., SIP dialog-initiating request for IP calls).
■ Tag: The tag corresponds to the matched prefix of the source and/or destination number and is
the categorization result.
You can use various syntax notations to configure the prefix numbers in dial plan rules. You can
configure the prefix as a complete number (all digits) or as a partial number using some digits and
various syntax notations (patterns) to allow the device to match a dial pan rule for similar source
and/or destination numbers. For more information, see the description of the 'Prefix' parameter
(DialPlanRule_Prefix) described later in this section.
The device employs a "best- match" method instead of a "first- match" method to match the
source/destination numbers to prefixes configured in the dial plan. The matching order is done digit-
by-digit and from left to right. The numbers are first matched to the rule configured with the most
constrained (specific) character set. Most constrained implies that the dial plan pattern that has the
fewest possible matches for a digit is matched first. For example, if one rule contains the "x"
wildcard character, which has ten possible matches (i.e., 0-9) and another rule a specific digit (e.g.,
4), the rule with the specific digit is selected as the matching rule. The best match priority is listed
below in chronological order:
■ Specific character (prefix)
■ Number range
■ "x" wildcard, which denotes any digit (0-9)
■ Suffix, where the longest digits is first matched. For example, ([001-999]) takes precedence
over ([01-99]) which takes precedence over ([1-9]).
■ . (dot), which denotes any character
For example, the table below shows the best match priority of an incoming call with prefix number
"5234":
Dial Plan Prefix
523x
523([4]) or [(5234)]
523[2-6]
523.
5234
The following examples show how the best-matching method is done. Each example has two dial
plan rules which are shown listed in chronological order as they would be configured in the table.
■ For incoming calls with prefix number "5234", the rule with tag B is chosen (more specific for
digit "4"):
Prefix
523x
5234
■ For incoming calls with prefix number "5234", the rule with tag B is chosen (more specific for
digit "4"):
Prefix
Table 20-4: Dial Plan Best Match Priority
Dial Plan Tag
A
A
A
A
B
Tag
A
B
Tag
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Mediant 4000 SBC | User's Manual
Best Match Priority (Where 1 is Highest)
3
4
2
5
1