PBX Device Down? Here's How to Fix PBX System Issues (5 Steps)

November 27, 2019 7 min read

Julie Bai

Julie Bai

PBX Troubleshooting Guide - Beginners to Advanced - Featured Image

PBX (Private Branch Exchange) is a business phone system that helps companies overcome the physical limitations of a traditional telephone system. Everyone from a small business to a large enterprise can benefit from it.
You no longer have to rely on copper wires or spend a fortune on your communications. Thanks to PBX, companies can expand to new locations easily and serve their customers well wherever they are.
When you can clearly communicate with your employees, customers, and partners, you set yourself up for success. A flexible phone system is essential to make it happen.
But what if you experience echoes, busy signals, dropped calls, or audio issues?
If you’ve experienced these issues with your PBX phone system, there’s one thing you should know: there’s no reason to panic!
The causes of these issues are usually easy to identify and solve. In this article, we’ll lay the foundations of PBX systems, take you through some common issues with call quality, and show you how to fix them.

  1. Jitter
  2. Slow internet connection
  3. Latency
  4. Bad or inadequate router
  5. Network interference
  6. 5 steps to fix your PBX phone system

Types of PBX Phone Systems

1) Analog (legacy) PBX phone system

Analog PBX pre-dates the internet. It connects externally to the Public Switched Telephone Network (PSTN) with wiring and internally by extending the calls in the same way through the office PBX equipment.
It’s quite limiting compared to its digital counterpart. It’s a good option if you’re only looking to hold, mute, redial, or speed dial your calls. If you want to have additional call features or connect your phone system to emails and a CRM, you may look further.

2) On-premises PBX phone system

On-premise PBX, also known as an IP PBX, means you have PBX equipment on-site. The main difference to the analog PBX system is that IP routing is done with more current technology. The signaling is done with an IP phone to the IP PBX server.
On-premise PBX gives you modern call features while making the most of the equipment you already own. It’s also extremely safe. The downside? Its deployment and maintenance come with a steep price tag.

3) Hosted PBX phone system

Hosted PBX is a phone system entirely based in the cloud. It doesn’t require you to have on-site equipment—your service provider runs everything. There are no extra training and maintenance costs.
It’s a great option if you’re looking to scale or have remote employees. Of all PBX phone systems, hosted PBX is the easiest to get started with.
Related: 40+ Best VoIP Features Your Small Business Can’t Do Without

What Can Go Wrong in a VoIP System?

Your PBX phone system is a feature-rich setup that powers your business communication. That includes everything from crisp audio and video to messaging and emails.
Because these communication channels use the same network, some call quality issues may come up. In the next sections, we’ll break down the common PBX issues you can troubleshoot, and a step-by-step process to do so.

Before we give you the steps to find what might be wrong with your PBX phone system, let’s quickly go over some common PBX issues and what causes them.

Problem #1: Jitter

Call quality issues related to jitter manifest as disarranged sound. These issues happen because of the way phone calls are transferred over the internet.
When you’re on a call, your voice is converted into data packets. They’re sent over the internet to their destination—the person you’re speaking with. When there’s a delay in transmission, these data packets can get jumbled or have gaps.
You can fix high jitter with a jitter buffer. A jitter buffer temporarily stores data packets in the right sequence and transmits them in intervals. As a result, clear audio reaches its recipient with minimum delay.

Problem #2: Slow internet connection

Have bandwidth issues after switching to VoIP phone systems? There’s a chance your current bandwidth can’t handle the amount of data that needs to be transferred for VoIP calls to work.
Bandwidth is like a pipe: the more of it you have, the more information can travel down the pipe at once. Most internet service providers (ISP) offer bandwidth that works well for regular internet surfing, but not for an entire phone system to work smoothly.
We recommend that you have at least 100kbps of bandwidth per phone—business internet service providers offer it. Keep in mind that your other devices, such as printers, computers, fax machines, and credit card machines also utilize your bandwidth.

Problem #3: Latency

Do you find that you and your caller are talking over each other, and you can hear your own voice on the call? Also known as latency or VoIP delay, it’s a delay between when one person says something and the other person hearing it.
There are a few types of latency that happen on VoIP calls: propagation delay, handling delay, and queuing delay.
Latency can be solved and prevented by prioritizing VoIP traffic. Here are several ways this can be done:

  • Bandwidth reservation
  • Policy-based network management
  • Multi-Protocol Label Switching (MPLS)

Prioritizing VoIP traffic over the network will improve both latency and jitter.

Problem #4: Bad or inadequate router

Your network is configured correctly, and your bandwidth is sufficient. Then, the issue might be in your router.
Your router must be fast, compatible with your hardware, and able to prioritize VoIP traffic. Specialized VoIP routers are a great, cost-effective way to ensure the best call quality.
If your router isn’t configured for packet prioritization, other activity on your network can lower your call quality. For example, if you’re on a call and someone else is watching a webinar or downloading a large file, your call quality could suffer.
Related: Hosted PBX Vs. SIP Trunking: Top 7 Differences & Why It Matters

Problem #5: Network interference

If you run your VoIP service concurrently with a data network over the same hardware, you may encounter bandwidth limitations. This is because both the data network and the voice network compete for resources.
These limitations can manifest as sound cutting in and out over the phone.
Two possible solutions include:

  • Configuring the network into separate VLANs so you can prioritize the data from the voice network over the data network
  • Utilizing a Quality of Service (QoS) feature of your business-class network to prioritize voice data

As a result, you’ll experience stable, quality phone calls every time.

Troubleshooting PBX Phone Systems in 5 Steps

With these common PBX issues in mind, here are the steps you can take to identify them. After that, you’ll know exactly what to do to fix your PBX system.

1) Check all device connections

First, make sure that your devices are connected to a power supply and the network. Check if all of your hardware, including phones, routers, and adapters, are plugged in correctly, including the power cords and network/telephone cords.
Remember also to check if all the lights on these devices are on. In case a device is plugged in, but isn’t receiving power (due to a faulty power socket, for example), this is how you’ll find it and know it needs to be fixed or replaced.
If all your devices are powered up, move onto the next step.

2) Reset your PBX and your hardware

Reset your PBX hardware. You can do this by unplugging the main cord for one minute.
Reset your equipment (phones and routers) as well by unplugging all power cords for 10 seconds.
Once you plug everything back in, wait for all the lights to turn back on. This will clear any fundamental issues that may have caused poor call quality. If any of your devices haven’t powered back up, flag it for repair or replacement.
If everything works fine, move onto the third step.

3) Run a bandwidth speed test

With a speed test, you’ll learn if your network is compatible with VoIP. Inadequate bandwidth and other connectivity issues limit the number of VoIP phones you can have. There may also be an issue with data packet transmission.
Nextiva has a simple and easy-to-use VoIP speed test. With it, you can uncover your:

    • Download and upload speed: Remember that you need around 100kbps of bandwidth for each phone you have

    • Ping: A packet loss test will shed light on potential network issues

    • Jitter: If it’s higher than 15-20ms, it can increase latency and result in packet loss

If you identify issues with any of the above, your solutions will include talking to your internet service provider (ISP) about increasing your bandwidth or getting a jitter buffer if you don’t have one.
No issues here? Jump to the next step.

4) Confirm your router has prioritized VoIP traffic

As we mentioned earlier, your router should be able to prioritize VoIP traffic, and your network configuration should be set up in the right way to enable it.
If your router has that option but isn’t set up correctly, start with this guide and your router’s manual to set it up.
If this isn’t an option with your existing router, it might be time to upgrade it to a quality VoIP router.
By this point, you’ve probably identified your PBX issues and the steps to fix them. If not, there’s one final step to take.

5) Use the logs in your PBX

Log into your PBX dashboard to view any errors that may have happened with your PBX.
In your PBX system, look for a section that shows you a log of events and messages about your PBX.
If you see any messages that indicate an error, open them to find dates, times, and details on that error, as well as the current status. You can then relay this message to your PBX administrator.

Related: What is SIP Trunking? How it Works, Benefits & How to Get It

Gain Control Over Your Call Quality

Running your communications over the internet means you can grow and scale your business easily while serving your customers well.
If you come across some call quality issues, you now know they’re easy to identify as long as you follow our five simple steps to fix your PBX system. Even better, you can do most of the process on your own.
That means you can get back to running your business better than before.

Tired of your fixing an unreliable PBX?
Upgrade to the cloud. We’ve got your back.
Julie Bai


Julie Bai

Julie Bai was a product manager at Nextiva, UCaaS evangelist, no-bull communicator, and translator for people, dog lover, and mother to an adorably active boy.

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