R2511-HP MSR Router Series Voice Configuration Guide(V5)

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4. The gateway initiates a call to the called side and sends the calling and called numbers.
On the called side
Figure 27 shows the dial plan operation process on the called side.
Figure 27 Flow chart for dial plan operation process on the called side
1. After receiving a voice call (the called number), the voice gateway on the called side performs
global calling/called number substitution.
2. The voice gateway on the called side selects proper voice entities based on the voice entity
selection priority rules. (Number substitution might also be involved during the voice entity
selection.) If the called party is a local voice subscriber, the gateway directly connects the
subscriber line. If the called party is a PSTN subscriber, the gateway initiates a call and sends the
calling and called numbers to the PSTN. The PBX in the PSTN connects the call.
Regular expression
You will frequently use some regular expressions when you configure number substitution rules. Regular
expressions are a powerful and flexible tool for pattern matching and substitution. They are not restricted
to a language or system and are widely accepted.
When using a regular expression, you need to construct a matching pattern according to certain rules,
and then compare the matching pattern with the target object. The simplest regular expressions do not
contain any metacharacter. For example, you can specify the regular expression "hello", which matches
only the string "hello".
To help you construct flexible matching patterns, regular expressions support some special characters,
called metacharacters, which define the way other characters appear in the target object. Table 12
de
scribes these metacharacters.