What's Asterisk? How to set up your Asterisk IP PBX?

The "Asterisk" is an open-source software capable to transform an ordinary PC into an IP PBX, it's also capable to transform a PC into any telephony application including call centers, Internet telephony service providers, and any custom telephony application you can imagine. 

Asterisk is a huge disruptive project. According to the website asterisk.org, there are more than 1 million Asterisk servers up and running across the globe.  

Origin - Asterisk Project

Back in the day, IP telephony was really expensive. Enterprises needed to pay an average of $1500 for voice logger, $2500 for interactive voice response, and $4000 for automatic call distribution and computer telephony integration.

It all began when Mark Spencer the founder of Asterisk wanted a telephone system for his company "Linux Support Services" back in 1999. The proposals he received from the mainstream telephone vendors were way above the LSS budget, approx $50k.

Mark decided to come up with his own code for a Telephony system with his previous expertise in telecommunications system development.

A computer software run telephone system, of which the core codes were developed and published within months, and code was made available to the public over the internet under GPL license.

And in 2001 "Linux Support Services" was renamed "Digium", and along with contributions from developers worldwide released upgraded versions of the Asterisk software which is free, open-source, and open standards, a huge huge disruption!

How to build your own PBX?

Let me show you how to build the PBX and what's the big picture.

• How to choose the hardware?
• How to choose the software?
• How to connect trunk lines -- network connection?
• How to choose phones?
• How to configure?

Hardware

The server configurations completely depend on the expected concurrent calls and API integrations with third-party software, you can see below a spec recommendation for a 500 user enterprise PBX.

A normal PC with a lesser configuration would also do the job. But it's recommended to use stable hardware as the PBX machines run almost 24/7/365.

Supported OS: Fedora, Ubuntu, CentOS, RHEL, and Debian Linux

Software

The main option is to just download asterisk and run, it's harder but flexible so you have to configure everything manually via backend. There's no graphical user interface but if you integrate applications I truly recommend that you learn asterisk.

You can use some alternatives like FreePBX or Issabel, they have a graphical user interface that is easier to configure.

I recommend to learn asterisk first and then go to the FreePBX or Issabel

Isabel is a fork of the open-source versions of "Elastix", which was having a very nice interface as an evolution of free PBX and have a very good contact center interface.

Trunk Lines

We can connect to the public network using different trunk lines, we have Analog PSTN, E1/T1, SIP trunk, and GSM.

To connect your PSTN lines we can use an FXO gateway and an E1 card/gateway to connect E1 PRI lines.

For SIP trunking with an Asterisk server you don't need any additional hardware, just connect to the internet using the Ethernet port of your server directly to the SIP trunk.

You can connect the GSM network using a gateway, and in many countries, this makes sense because of the cost of the mobile calls.

Phones

An Asterisk server can connect with any SIP-based extension, below architecture shows the type of extensions which can be connected with your Asterisk server.

These days, softphone applications are free of cost and would work very well with Asterisk PBX servers.

IP Phones/Desk phones are a type of extension which is commonly used within an office infrastructure.

There are low-end phones which would cost around $30, there are manufacturers such as Yealink, Grandstream, Sangoma, Polycom, Fanvil, etc. which are very nice phones.

Your existing Analog phones which come with RJ11 cabling still can be utilized with an Asterisk PBX using FXS gateways to connect phones.

The server can further connect and communicate with conference room phones, SIP speakers (paging), and video phones.

Configuration

There are many articles on the web that provide step-by-step Asterisk installation guide and software codes. If you are tech-savvy, you can figure out the way yourself to install Asterisk from scratch.

Also, we at VoIP Savvy provide complete Asterisk training, and professional services such as Asterisk consultation, installation, configuration, customization, 3rd party integration, and 24/7 technical support.

The big picture

Now looking at everything

Here you have the Asterisk server connected to the phone trunk lines, using required gateways and cards.

GSM, E1 PRI, SIP, VoIP, and PSTN are compatible with Asterisk servers. A combination of these can be used as per the business need.

On another hand side, there are a wide variety of extensions that can be configured on the Asterisk server, using a softphone in Android/iOS helps businesses eliminate office wiring and hardware dependency.

And of course, the dedicated Asterisk server sits within the office network or in the cloud. And can be integrated with your favorite enterprise applications over API.

Asterisk has several applications in the enterprise world, it can provide Cloud PBX and Call Center, Interactive Voice Response, Voice application portals, Web telephony (WebRTC), and almost any type of telephony.

To Summarize, the Asterisk application is very open and very extensible.

It is a powerful telephone engine created by Mark Spencer and Digium (earlier Linux Support Services) envisioned in 1999, recently bought by Sangoma, its free, open-source, and open standards-based.

I would be happy to answer any questions regarding an Asterisk-based PBX system for your business and show you its integration capabilities with external software :)

If you've found this article informative, don't forget to give a thumbs-up, and feel free to share this quick explanation with your network.

Thanks,