Building and Configuring Asterisk: Essential IT Knowledge

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What is Asterisk configuration? How to build a standard IT configuration? To better understand this, let’s explore the article below!

Configuring Asterisk

If you have questions about WebRTC compatibility with a specific Asterisk version, please direct those questions to the appropriate Asterisk support forums.

Setting up the Asterisk system

Asterisk and SIP.js have been tested using the following setup:

• CentOS 7.2 minimum (x86_64) Asterisk 16.9.0;
• OpenSSL 1.0.1e-fips February 11, 2013 or later;
• A public IP address to avoid server-side NAT scripts;
• Disable SELinux;
• Package requirements.

Install the following dependencies:

Installing Asterisk

cd /usr/local/src/.

1. Download Asterisk using wget https://downloads.asterisk.org/pub/telephony/asterisk/asterisk-16.9.0.tar.gz.
2. Extract Asterisk: tar zxvf asterisk*.
3. Import the Asterisk directory: cd /usr/local/src/asterisk*.
4. Run the Asterisk script configuration: ./configure –with-jansson-bundled.
5. Run the Asterisk menuselect tool: make menuselect.

In the selection menu, go to the resources option and ensure that res_srtp and pjproject are enabled. If there are three x’s next to res_srtp, there is a problem with the srtp library and you must reinstall it. Save the configuration (press the x).

Compile and install Asterisk: make && make install.

If you need sample configuration, you can run make samples to install sample configuration. If you need to install the Asterisk startup script, you can run make config.

Setting up a DTLS certificate in Asterisk

Self-signed SSL certificates may be acceptable for development, but they will not work in a production environment. Let’s Encrypt is a great way to get a free certificate.

Self-signed certificate

mkdir /etc/asterisk/keys

Enter the Asterisk scripts directory: cd /usr/local/src/asterisk*/contrib/scripts.

Create a DTLS certificate (replace pbx.mycompany.com with your IP address or DNS name. Then, replace My Super Company with your company name): ./ast_tls_cert -C pbx.mycompany.com -O “My Super Company” -d /etc/asterisk/keys.

What is Asterisk Configuration?

Asterisk Configuration for WebRTC

For WebRTC, many of the necessary settings must reside within the peer settings. Global settings don’t flow down to peer settings very well. By default, the Asterisk configuration file is located in /etc/asterisk/. Start by editing http.conf and ensure that the following lines are not corrupted:

Change the IP address and port to your server’s IP address and the port on which you want Asterisk to listen for web socket connections.

Next, edit sip.conf.

Here, you will set up two peer machines, one for the WebRTC client and one for the non-WebRTC SIP client. WebRTC peer requires encryption, avpf, and icesupport to be enabled. In most cases, directmedia should be disabled. Also in the WebRTC client, the transport needs to be listed as ‘ws’ to allow websocket connections. All these configuration lines must be under itself; setting these configuration lines globally may not work.

Finally, set up extensions.conf to allow the two colleagues to call each other.

;extensions.conf

[default]

exten => 1060,1,Dial(SIP/1060) ; Dialing 1060 will call the SIP client registered to 1060

exten => 1061,1,Dial(SIP/1061) ; Dialing 1061 will call the SIP client registered to 1061

Restart Asterisk using the service asterisk restart to ensure that the new settings take effect.

Troubleshooting in Asterisk

The WebRTC troubleshooting forum post is a great guide for issues when capturing with Asterisk.

The Asterisk secure calling guide can help you set up dtls certificates.

Source: sipjs.com

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