The asterisk.conf configuration file allows you to tweak various settings that can affect how Asterisk runs as a whole.

There is a sample asterisk.conf file included with the Asterisk source. It is not necessary to have this file in your /etc/asterisk folder in order to have a working system, but you may find that some of the possible options will be of use to you.

$ sudo asterisk -C /custom/path/to/asterisk.conf

$ man asterisk

This file is not strictly required in an Asterisk installation; however, without any modules Asterisk won’t really be able to do anything, so for all practical purposes, you need a modules.conf file in your /etc/asterisk folder. If you simply define autoload=yes in your modules.conf file, Asterisk will search for all modules in the /usr/lib/asterisk/modules folder and load them at startup.

Although most modules do not use much in the way of resources, and they all load very quickly, it just seems cleaner to our minds to load only those modules that you are planning on using in your system. Additionally, there are security benefits to not loading modules that accept connections over a network.

In the past we felt that explicitly loading each desired module was the best way to handle this, but we have since found that this practice creates extra work. After every upgrade we found ourselves having to edit the modules.conf file to correct all the module differences between releases, and the whole process ended up being needlessly complicated. What we prefer to do these days is to allow Asterisk to automatically load the modules that it finds, but to explicitly tell Asterisk not to load any modules we do not want loaded by use of the noload directive. A sample modules.conf file can be found in the section called “modules.conf”.

The sounds that people expect from the telephone network vary in different parts of the world. Different countries or regions present different sounds for events such as dialtone, busy signal, ringback, congestion, and so forth.

The indications.conf file defines the parameters for the various sounds that a telephone system might be expected to produce, and allows you to customize them. In the early days of Asterisk this file only contained sounds for a limited number of countries, but it is now quite comprehensive.

To assign the tones common for your region to channels, you can simply assign the tonezone using the CHANNEL() function, and that tonezone will apply for the duration of the call (unless changed later):

Set(CHANNEL(tonezone)=[yourcountry]) ; i.e., uk, de, etc.

However, since signaling from a call could come from various places (from the carrier, from Asterisk, or even from the set itself), you should note that simply setting the tonezone in your dialplan does not guarantee that those tones will be presented in all situations.

[starwars](us)
description = Star Wars Theme Song
ring = 262/400,392/500,0/100,349/400,330/400,294/400,524/400,392/500,0/100,349/400, \
       330/400,294/400,524/400,392/500,0/100,349/400,330/400,349/400,294/500,0/2000

exten => 500,1,Answer()
    same => n,Set(CHANNEL(tonezone)=starwars)
    same => n,Dial(SIP/0000FFFF0002) ; or whatever your channel is named in sip.conf

While Asterisk will run without an indications.conf file, it is strongly recommended that you include one: copy the sample over with sudo cp ~/src/asterisk-complete/1.8/configs/indications.conf.sample, modify the country parameter in the [general] section to match your region, and restart Asterisk.

If your system supports multiple countries (for example, if you have a centralized Asterisk system that has users from different regions), you may not be able to simply define the default country. In this case, you have a couple of options:

For more information about using Asterisk in different countries, see Chapter 9, Internationalization.

If you plan on selling Asterisk-based telephone systems and you do not change the default music on hold that ships with Asterisk, you are sending the message, loud and clear, that you don’t really know what you are doing.^[41]

Part of the problem with music on hold is that while in the past it was common to just plug a radio or CD player into the phone system, the legal reality is that most music licenses do not actually allow you to do this. That’s right: if you want to play music on hold, somebody, somewhere, typically wants you to pay them for the privilege.

So how to deal with this? There are two legal ways: 1) pay for a music on hold license from the copyright holder, or 2) find a source of music that is released under a license suitable for Asterisk.

We’re not here to give you legal advice; you are responsible for understanding what is required of you in order to use a particular piece of music as your music on hold source. What we will do, however, is show you how to take the music you have and make it work with Asterisk.

$ rpm -Uhv http://apt.sw.be/redhat ...

$ yum install yum-priorities

$ yum install mpg123

$ mpg123 -w SilentCity.wav SilentCity.mp3

$ sox SilentCity.wav -t raw -r 8000 -s -w -c 1 SilentCity.sln

# sudo apt-get install sox libsox-fmt-all

$ sox SilentCity.mp3 -t raw -r 8000 -s -w -c 1 SilentCity.sln

$ cp *.sln /var/lib/asterisk/moh

$ asterisk -rx "module unload res_musiconhold.so"
$ asterisk -rx "module load res_musiconhold.so"

exten => 664,1,NoOp()
    same => n,Progress()
    same => n,MusicOnHold()

This chapter helped you complete some initial configuration of Asterisk. From here you can move on to setting up some phones and taking advantage of the many features Asterisk has to offer.