This dial plan application is used for assigning value to a variable. In Asterisk dialplan application we can see that applications like SetCIDName, SetCIDNum, SetLanguage, SetVar are being deprecated in favour of Set ( Set(CALLER(name)=…), Set(CALLER(number)=…), Set(LANGUAGE()=…)).

Have a look at the example below.

First of all you need to install Asterisk PBX. Afterwards you need to configure at least one user in iax.conf, sip.conf or mgcp.conf – the protocol you are going to use depends on you or of the phone you are using. After this you need to write some extensions in extensions.conf.

In this tutorial I will use Idefisk softphone that is an IAX client. You can download it by clicking here. Tutorial showing how it works and configuration support can be found here.

NOTE: This is just an example of what you can use this application for. Of course you can use it and for other purposes.

When you have installed and working Asterisk PBX you will need some user to test this application. If you do not have any registered in iax.conf you may add the following one. If you are not going to user Idefisk Softphone and iax.conf you have to register the user in the same way in sip.conf, h323.conf or mgcp.conf – depending on the protocol you are using.

So, we have registered the users anatoliy, user1 and user2.

Type=friend means that this user can make and receive calls. Host=dynamic means that the IP is not static but dynamic through a DHCP server. Allow=all means that the line which this user will use, could support all audio codecs. Context=test - this shows that this user is working with the extensions in this context of the configuration file extensions.conf.

We now have a user that can use the context [test] from extensions.conf. So now we need some dial plan application in [test] in extensions.conf.

Here is the application in extensions.conf. Note that the priority “n” is used. This means that the priority will be the next number – so I just give the initial value 1 and then the priority will increment with one each time.

NOTE: When you define a variable _var or __var you just call it ${var}.

If you see unknown so far applications for you have a look at the following tutorials:






exten => 123,1,Answer()
The call is answered.

exten => 123,n,Playback(welcome)

Welcome message is played on playback.



exten => 123,n,Set(a=aaa)
Variable “a” is defined and value “aaa” is assigned to it.

exten => 123,n,Set(_b=${EXTEN})
Variable “b” is defined and value “${EXTEN}” is assigned to it. It is defined with underscore prefix, so it will be inherited in the inherited channel. ${EXTEN} is an asterisk-defined variable and is case sensitive and returns the extension you have dialed.

exten => 123,n,Set(__c=${CALLERID})
Variable “c” is defined and value “${CALLERID}” is assigned to it. If is defined with double underscore prefix, so it will be inherited in every inherited channel. ${CALLERID} is an asterisk-defined variable and is case sensitive and returns the caller id.

exten => 123,n,Dial(Local/alpha@test)
This dials locally the extension alpha at the context test. Usage is: Dial(Local/extension@context).
For more information have a look at the dial tutorial.

exten => alpha,1,Answer()
The call is answered.

exten => alpha,n,NoOp(${a})
Variable “a” is dumped in CLI

exten => alpha,n,NoOp(${b})
Variable “b” is dumped in CLI

exten => alpha,n,NoOp(${c})
Variable “c” is dumped in CLI

exten => alpha,n,Dial(Local/bravo@test)
This dials locally the extension bravo at the context test. Usage is: Dial(Local/extension@context). For more information have a look at the dial tutorial.

exten => bravo,1,Answer()
The call is answered.

exten => bravo,n,NoOp(${a})
Variable “a” is dumped in CLI.

exten => bravo,n,NoOp(${b})
Variable “b” is dumped in CLI.

exten => bravo,n,NoOp(${c})
Variable “c” is dumped in CLI.

exten => bravo,n,Hangup()
HangUp() closes the channel line.

Here is what you will see in CLI. When the call is answered and welcome message is played variables “a”, “_b” and “__c” are set. Then you are redirected to the next channel – alpha. When the channel is answered the variables are dumped and send to another channel – bravo. The channel there is answered and again the variables are dumped and the channel is closed. The variable a is valid just for the 123 channel and variable __c is valid as for the channel 123 so for all inherited channels (alpha and bravo).