The purpose of this application is to allow you to strip the digits from the beginning of an already existing extension number.

In this way you can easily change the extension number. This feature is useful within big and complicated dialplans.

Below, we will give you an example.

To use this application you need a working Asterisk PBX with registered users in iax.conf, sip.conf or mgcp.conf(It depends on which protocol you would like to use) and made extensions.

To see how the application works we recommend to use our IAX softphone Idefisk. You can download it from here. Please also read our tutorial to learn how to configure it to work with Asterisk PBX.

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

We need one registered user in iax.conf file. This is because we are going to use the IAX2 protocol. If you want to use other protocol such as SIP or MGCP, you have to do the configurations below respectively in sip.conf or mgcp.conf.

So, we have registered the user user1

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.

On the picture above you can see our extensions.conf file.

In our example when somebody dials 10101111, the call will be answered by the Answer application. The next executed extension will be the one which contains the SendText application. Thanks to it, we will check the content of the ${EXTEN} variable. It should be the number of the dialled extension. In our example the application will send a message to the caller with the following text: The current extension is: 10101111.

The next executed extension will be the one with the Wait application. It will give us time before the next message. We have set the time to 5 seconds.

The next executed extension will be the one with the StripMSD application. In its brackets we have set the following: 4. This will cause the change of the number of the next executed extension. In other words, as argument in the brackets, we have set the number of digits which we would like to be stripped from the beginning of the extension number. The number 4 means that we would like to remove the first four digits from the extension number. The number in our case will be changed to 1111.

NOTE: Please, pay attention that as argument in the brackets you have to set the number of digits, you would like to be removed, not the digits themselves.

Now, the number of the next extension - the one with priority 5, should be 1111 instead of 10101111. This extension will use again the SendText application to check, what is the new content of the variable ${EXTEN}. It should be 1111. Thanks to this application, on the screen of the caller will be displayed the following message: The new extension number is: 1111.

In order to be sure that the Asterisk PBX will hang up the line after the conversation is over, it is a good idea to make an extension for hanging up the line.