Getting to Know Dial Plans Sequences

From Asterisk Australia

Q. What are Dial Plan Sequences?

A sequence may require an explicit pause of some duration before continuing to dial digits, in order for the sequence to match. The syntax for this is similar to the timer override syntax  The delay-value is measured in seconds and allows for the implementation of Hot-Line and Warm-Line services. To achieve this, one sequence in the plan must start with a pause, with a 0 delay for a Hot Line and a non-zero delay for a Warm Line.</p>

Implicit Sequences
The SPA implicitly appends the vertical code sequences entered in the Regional parameter settings to the end of the dial plan for both line 1 and line 2.  Likewise, if Enable_IP_Dialing is enabled, then IP dialing is also accepted on the associated line. To become familiar with the various dial plans, please refer to the items that are in bullets seen below.

• The following dial plan only accepts US-style 1 area-code local-number, with no restrictions on the area code and number.

• The following also allows seven-digit US-style dialing and automatically inserts a 1 212 (local area code) in the transmitted number.

• For an office environment, the following plan requires a user to dial 8 as a prefix for local calls and 9 as a prefix for long distance. In either case, an "outside line" tone is played after the initial 8 or 9 and neither prefix is transmitted when initiating the call.

• The following allows only placing international calls (011 call), with an arbitrary number of digits past a required five-digit minimum and allows calling an international call operator (00). In addition, it lengthens the default short interdigit timeout to four seconds.

• The following allows only US-style 1 area-code local-number, but disallows area codes and local numbers starting with 0 or 1.  It also allows 411, 911, and operator calls (0). 

• The following allows US-style long distance but blocks 9xx area codes.

• The following allows arbitrary long distance dialing but explicitly blocks the 947 area code. 

• The following implements a Hot Line phone, which automatically calls 1 212 5551234. 

• The following provides a Warm Line to a local office operator (1000) after five seconds, unless a four-digit extension is dialed by the user.