Is Open Source PBX the Right Choice for Your Business?

For any business, an effective way for employees to communicate and to send and receive calls is very important. The best option available for businesses of most sizes is a digital PBX. A PBX, or private branch exchange, is the switchboard system a company uses to route calls. A digital PBX is a PBX that handles VoIP calls rather than traditional analog calls.

What are your options in office PBXs?

  • Analog PBX: An analog PBX is the traditional wired hardware system that businesses have historically used to route calls in an office. Originally, an analog PBX needed to be manually operated.
  • Virtual PBX: A PBX that is hosted by the service provider out of an off-site location.
  • On-Site IP PBX with a SIP Trunk: A hardware or software PBX solution that a business will host in their own office. If you want to use an on-premise PBX solution, you need to provide your own SIP Trunk service (the part of the phone system by which calls are relayed in and out of the office).

While some businesses do still use analog PBXs, most of the time these are companies that already had an analog PBX and don’t want to replace it. Very few companies buy new analog PBXs because they are cumbersome and expensive to own and operate. In general, business owners are much more likely to choose a VoIP solution for their business phone service. Either a Virtual PBX or an on-premise PBX with SIP trunking.

What is a Virtual PBX?

A Virtual PBX is a virtual switchboard that requires no on-site device. The VoIP service provider literally “hosts” the PBX and so manages all of the associated functions of a PBX, like call routing. The business accesses and programs their Virtual PBX through an online cloud platform.

Virtual PBX services are very easy to use, and are ideal for companies that are not capable of owning and managing their own PBX systems. However, while Virtual PBXs are much cheaper than analog PBXs (about $20/extension per month versus analog PBXs which can cost in the hundreds of thousands of dollars each year), Virtual PBXs are generally more expensive and less customizable than on-premise IP PBXs.

What is an On-Premise IP PBX?

Many businesses are better suited to on-premise IP PBX solutions because on average, on-premise IP PBXs with SIP trunking components are cheaper than hosted solutions. Companies can choose from both hardware and software IP PBX platforms. These platforms can range from free open source PBX software like Asterisk, up to a few thousand dollars for some of the PBX hardware platforms.

Large businesses with capable IT staff should strongly consider a SIP Trunking solution, as should any business that has more extensions than simultaneous calls; that is, with an on-premise IP PBX and a SIP Trunk solution, you only need to figure out how many simultaneous incoming or outgoing calls you will ever have at a given time and buy an appropriate number of SIP Trunks.

So, if your business has 30 extensions but you only expect 5 simultaneous calls, you will only need to pay for 5 SIP trunks at about $10/month each. Compare that to the cost of a hosted solution in which you would have to pay $20 each month for each extension so that there is no limit on the number of inbound or outbound calls you can have at any time. However, if you don’t need every extension to have full external calling capabilities at the same time, there’s no reason you should pay so much for each extension.

Wait, go back to that part about a free open source PBX…

An open source PBX is an in-house IP PBX built using free and fully upgradeable software. It’s basically a DIY phone system.

Anyone that feels up to the challenge can download the open source PBX software, Asterisk is among the most popular, and start designing their business VoIP service.

All you need to get set up with a free open source PBX program is a dedicated computer and a capable programmer. You can program your open source PBX with all of the features and options you want. Then, you just get your SIP Trunk service set up and your office will have full office calling capacity.

Alternative PBXs can have a fairly expensive one-time cost, and frequently, if you buy a ready-made software PBX, you are really just buying a pre-programmed version of an open source PBX that you could download for free.

What are the Benefits of an Open Source PBX?

The most obvious benefit to an open source PBX is the savings. Without having to purchase a $1000 IP PBX, a business wouldn’t have any one-time costs to make up. Since SIP Trunking is a cheaper route for most business VoIP subscribers, they continue to save money every month.

Additionally, whoever designs the business’s open source PBX can program any features they want. This means that a company is not limited to the pre-programmed features of a hosted PBX service, and they don’t have to have any features that they don’t want.

How Does an Open Source PBX Compare?

The one main caveat to designing an open source PBX is you have to be knowledgeable enough to do it. Or you can hire someone to design it for you if you’re not. That leads into another important detail about an open source PBX: support.

Any type of IP PBX, open source included, needs a technical support staff on hand. They help maintain the on-site IP PBX and troubleshoot any problems that arise. And in an ideal scenario, they would be responsible for programing the open source PBX. At the same time, keeping a support staff on hand is an extra cost to the business, but likely necessary for any larger business.

An open source PBX option might not be for those very small businesses, like a Mom and Pop store for example. Companies that need a PBX, but don’t make a lot of calls, however, will find that the open source option beats purchasing a hardware IP PBX or going with a hosted PBX service. It ultimately comes down to whether you want to pay for setup and maintenance, or let the provider handle it off-site at a slightly higher cost.

This article is a guest post from Rachel Greenberg. Rachel is the site editor for

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