Finding software can be overwhelming. Software Advice helps businesses choose the right IP PBX software so they can save money with SIP trunking and get the phone system features they need.

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GoToConnect

GoToConnect (formerly Jive) delivers a cloud-based unified communication solution to organizations of all sizes across the U.S. GoToConnect includes integrated products for business VoIP, video conferencing and contact center whic... Read more

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Recent recommendations: 22 recommendations

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Nextiva

Nextiva is a platform that brings communications together with business applications, intelligence, and automation. This helps businesses communicate and build deeper connections with their customers. The platform brings all ... Read more

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Recent recommendations: 19 recommendations

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RingCentral MVP

RingCentral MVP is a cloud-based business communications solution that offers tools for Messaging, Video and Phone. Core features of the solution include conferencing, auto-recording and unlimited long-distance and local calling. ... Read more

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Recent recommendations: 16 recommendations

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PanTerra Streams

Business Plus is a cloud-based VoiP solution created by PanTerra, which allows users to take or make calls from their office phone number, communicate with their team, and have file access, all from any device with an internet con... Read more

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Recent recommendations: 12 recommendations

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8x8 Virtual Office

Virtual Office is a collection of comprehensive web-based business VoIP solutions from offered by 8x8. Enterprise grade phone service, virtual meetings, mobile applications, virtual contact centers and more are available to help c... Read more

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Recent recommendations: 10 recommendations

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Ooma Office

Ooma Office is a cloud-based voice + video solution suitable for businesses of all sizes. The platform includes a full suite of business phone features designed to deliver a flawless communications experience and advance team coll... Read more

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Recent recommendations: 10 recommendations

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BroadVoice Cloud PBX

BroadVoice b-Hive helps call and collaborate from anywhere with a single cloud communication solution that unifies business phones, video conferencing, texting and collaboration under a single phone number. Untether your team fro... Read more

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Recent recommendations: 9 recommendations

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Vonage Business Communications

Vonage Business Solutions is a cloud-based communications solution suitable for small and midsize companies. The solution offers a business phone system that enables businesses to connect their VoIP phone system to internet-enable... Read more

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Recent recommendations: 8 recommendations

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VirtualPBX

VirtualPBX is a cloud-based phone solution that caters to all-sized businesses. VirtualPBX enables companies to streamline and improve communications with features such as unlimited minutes, video conferencing, business SMS, auto-... Read more

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Recent recommendations: 4 recommendations

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Comm-unity

Comm-unity by NetFortris (formerly Fonality) is a cloud-based communication and collaboration business phone system that caters to all business sizes. Comm-unity scales easily as your business grows, always works when you need it,... Read more

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Recent recommendations: 4 recommendations

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Dialpad

For quickly growing businesses looking to efficiently scale their support teams, Dialpad provides a cloud-based call center with access to real-time customer insights. Dialpad allows users to onboard quickly and focus on deliverin... Read more

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Recent recommendations: 2 recommendations

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Join.Me

Join.me is an online meeting platform that helps businesses manage meetings and team collaboration. Key features include real-time presentations, mobile whiteboards, scheduling, toll-free audio, chat and more. Designed f... Read more

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Talkdesk

Talkdesk is a cloud-based call center solution that helps businesses improve customer satisfaction while simultaneously reducing customer support costs. It uses interactive voice response (IVR), automatic call distribution (ACD) a... Read more

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NICE CXone

With the highest reliability ratings in the call center software market, inContact helps its customers optimally process over one billion calls per year. ... Read more

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BlueJeans

BlueJeans is a cloud-based video conferencing solution that helps mid to large size businesses with text chat, content sharing, multiple participants and meeting recording. Blue Jeans delivers services through products including B... Read more

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Five9

Five9 is a hosted call center system that can be used across call centers of all sizes. It's suitable for companies in the retail, telecommunications, banking and health care industries.... Read more

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Grasshopper

Grasshopper is a cloud-based virtual phone service that helps small to midsize enterprises establish communication with customers through local and toll-free numbers. It provides several modules, including call forwarding, multipl... Read more

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CallHippo

CallHippo is a cloud-based call center solution that helps mid to large size businesses with workflow automation and virtual telephony. The platform enables users to give detailed analysis to customers through call recordings. Cal... Read more

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Twilio

Twilio is the worlds leading cloud communication platform that enables you to engage customers across channels - SMS, voice, video, email, WhatsApp and more. Pay-as-you-go APIs allow businesses to scale communications reliably. ... Read more

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3CX

3CX Phone System is a software-based IP PBX for Windows. In addition to a range of PBX features, 3CX offers Web conferencing via Web Real-Time Communication. Modules are available for hotels, call centers and CRM integrations. ... Read more

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Buyers guide


Last Updated: October 16, 2021

The term “PBX,” for private branch exchange, is in most cases simply a synonym for business phone system.

Internet Protocol PBXes, or IP PBXes, are phone systems that connect calls via the internet rather than the traditional phone network.

We’ll explain the core features and benefits of IP PBX systems. We’ll also take a look at some of the key factors that businesses need to consider when investing in a new phone system.

Here's what we'll cover:

  • What Is a PBX and an IP PBX?
  • IP PBX
  • Which Businesses Need Them?
  • Key Considerations

What Is a PBX and an IP PBX?

The term PBX itself is a relic from the early-20th Century, as we explain in our extended definition.

 

Switchboard Operators, public domain image

Broadly speaking, a PBX’s function is to unite all the separate phone extensions that a business uses so they can function together as one system. Specifically, PBXs:

  1. Route incoming calls to whichever extension a caller chooses.
  2. Distribute calls automatically to internal extensions based on pre-set rules.
  3. Connect internal extensions to outside lines when employees place a call.
  4. Connect calls internally between the business’s extensions.

PBXs have been performing these same tasks for decades. As the internet increasingly takes over the function of the traditional phone network, however, the capabilities and features of PBXs have also evolved.

IP PBX

VoIP, or the Voice over Internet Protocol, has brought many changes to all aspects of business telephony—PBXs included. With VoIP, it’s now possible to send calls over an internet connection, as opposed to paying for traditional business phone service.

In order to reap the benefits of VoIP, you need an IP PBX rather than a traditional PBX, as an IP PBX system can connect directly to the internet. Older PBX systems, on the other hand, connect to analog or digital phone lines.

There are devices known as gateways that allow you to use VoIP service with an older PBX system. If you’re replacing your system, however, it makes much more sense to simply invest in an IP PBX.

IP PBXs exist in several very different forms. Although they all perform similar functions, there is no strict definition of the term. An IP PBX can refer to:

Hardware-based on-premise systems Specific on-site hardware devices that look much like typical rack-mounted servers.
Software-based on-premise systems PBX software running on a computer outfitted with phone connections.
Virtualized on-premise systems “Virtual machines” installed on commodity hardware running a virtualization platform such as VMware.
Cloud-based systems Systems hosted by a VoIP provider in the provider’s data center rather than a server on your business’s premises, delivered as a service over your Internet connection.

Which Businesses Need Them?

Traditionally, PBXs were very expensive to purchase and maintain, and they were only used by relatively large businesses. Smaller businesses had alternatives such as Key Systems, which are scaled-down and less automated, but perform similar functions. (With Key Systems, users manually select lines: for example, by pressing "9" for an outside line.)

Now it’s common for businesses with even a few employees to use some sort of IP PBX for their office phone system.

IP PBXs allow incoming calls to be routed and automatically distributed, and allow internal extensions to dial each other and share external lines. They provide the same basic functions as traditional PBXs, and can be useful to businesses of almost any size.

Further, as more businesses seek out the conveniences and cost-savings of VoIP telephony, IP PBXs in one of the forms mentioned above have become an increasingly common choice. Rather than trying to modernize an older PBX so it can work with VoIP calls, it often makes more sense to upgrade the whole system. Upgrading also gives buyers a chance to bring in new features which may have previously been unavailable.

Key Considerations

Hosted or on-premise. This is probably the most critical decision to make. Companies should look at both options. On-premise systems will typically have higher initial costs, and may also require periodic system maintenance. Hosted PBXs will cost less up front, and will be managed by the provider, but have higher recurring costs. The total cost of ownership for all potential systems should be compared.

Call capacity. PBXs can only handle a limited number of concurrent calls and a limited number of total extensions or “registrations.” (Each VoIP phone connected to the IP PBX requires a single registration.) Assess how many total connections you’ll need, count one for each hardphone and softphone you plan to connect, as well as any devices such as FAX machines that may also be connected via your existing phone service provider, and estimate how many calls your employees will be making and receiving simultaneously when you’re at peak call volume.

Unified communications. This term refers to a range of features that involve communicating across platforms and between different mediums. A common example of this is visual voicemail: a feature that automatically transcribes voicemail messages and emails the transcript to the recipient. Many IP PBXs have UC functions included.

Security. VoIP calls have special network requirements and they often don’t work with well with standard office firewalls. To avoid problems, ensure that your existing firewall is compatible with SIP and VoIP traffic. An alternative is to get an IP PBX that includes a built-in firewall, as many do. Many also include VPN gateways to connect with a corporate Virtual Private Network.

Finally, you can use a device known as a Session Border Controller (SBC), which provides additional security specifically for VoIP systems by policing the “pinholes” that you need to open in your firewall for your VoIP calls.

Auto attendant. This is the automated answering system that greets inbound calls, presents pre-recorded information and gives callers a list of extension options from which to choose. Most IP PBXs include auto attendants, but the level of functionality supported by different systems differs. Advanced IVR systems, the voice menus that allow callers to complete actions such as checking account balances over the phone, are generally only found in call center suites.