Common VoIP Problems and How To Fix Them

December 27, 2023 9 min read

Cameron Johnson

Cameron Johnson

How to Fix VoIP Problems

VoIP phones are great alternatives to landline systems. They offer better call quality and reliability at a fraction of the cost of traditional phone lines or PBX.

But even the best technology can encounter hiccups. If you’ve ever been on a VoIP call plagued by choppy audio, dropped connections, or robotic voices, you know the frustration.

83% of companies lost a customer, missed a major deadline, or terminated an employee due to a communication issue. You don’t want that happening to you due to a VoIP problem that’s easily resolved with the right knowledge and technology.

In this article, we’ll walk you through the most common VoIP problems and offer troubleshooting tips to fix recurring issues. You’ll save your IT staff time and get your business phone system in top shape in no time.

Common VoIP Problems

Voice over Internet Protocol (VoIP) systems send calls over the internet and rely on your local network and bandwidth capacity. A weak link in the chain can negatively impact voice quality.

How VoIP works

Here are the most common VoIP issues to be aware of and fix:

1) Poor call quality or choppy audio

Since VoIP calls are transmitted in real time as data packets, any disruptions to voice packets reaching a destined IP address will get heard as choppy, distorted, or delayed audio on calls.

If you’re experiencing call quality issues, look out for these common culprits:

How to fix choppy voice

Start by checking your internet bandwidth. Insufficient upload/download speeds are the most common cause of choppy VoIP calls.

Run speed tests and make sure you meet the bandwidth recommendations from your VoIP provider. Nextiva offers a handy VoIP speed test, enabling you to see how your network performs.

Next, test your network for issues like high latency/jitter or packet loss during calls and troubleshoot accordingly. This may involve router firmware upgrades or contacting your Internet Service Provider (ISP).

Network Jitter - Illustration showing what's happening
When packets arrive at unexpected times, VoIP calls can be interrupted.

A few more tips to fix choppy audio:

If the problem persists, check your VoIP network or VoIP device. Reach out to your telephony provider because a problem could be at their end.

2) Dropped calls

A VoIP call disconnecting abruptly is incredibly annoying. This usually happens on outbound calls on high-volume networks.

The first culprit is not having the most up-to-date firmware on your device. A quick call to your phone provider should confirm this.

The second issue might be a UDP Timeout, which is the amount of time a UDP route stays open on a firewall or router.

UDP network traffic is faster because it lacks the error-checking capabilities TCP offers. As a result, it’s susceptible to firewalls closing the connection and terminating the call unexpectedly.

How to fix dropped calls

Start by troubleshooting internet connectivity problems. If temporary ISP disruptions or using WiFi in dead zones causes dropped calls, use wired connections or mesh WiFi to strengthen signals.

Comparison of PoE standards and applications (via FS)
Comparison of PoE standards and applications (via FS)

3) Echo/feedback

Hearing your own voice reverberating back through the phone makes conversations very difficult.

Three potential problems cause echo/feedback on voice calls: audio configuration issues, headset lag, or network latency.

How to fix echo/feedback

Observe if the echo only occurs under certain conditions or directions to narrow down the root cause before troubleshooting.

VoIP QUality of Service
Routers prioritize voice traffic using QoS alongside other network demands.

If you still experience echoes, you may need to improve your network stability.

4) Call connects with no sound

Hello, can you hear me? One-way audio is a common VoIP issue.

Voice reliability depends on the intermediate network, firewalls, and audio software stack working properly.

Improperly configured VoIP phones, faulty/loose wiring and connectors, incompatible codecs, heavy network congestion, and QoS misconfiguration causing excessive latency, jitter, and packet loss can stop real-time audio despite calls connecting fine at VoIP protocol layers.

Packet Loss Percentage (%) Effect on VoIP Phone Calls
Packet Loss Percentage (%) Effect on VoIP Phone Calls

Your local system security software may also be blocking the RTP media traffic even while allowing the VoIP control traffic to flow normally.

How to fix call audio issues:

Fully plug headset/handset connections into the VoIP phone ports. Also, check the volume levels on the VoIP phones are turned up and not muted.

Inspect phone configurations to select the correct audio input/output settings. Devices may use wrong inputs like Bluetooth when wired headsets are expected.

Toggle between available codecs on the VoIP phones to rule out codec incompatibility issues. Also, reboot phones to reinitialize codec handshaking after switching.

Don’t forget to update VoIP phone firmware in case existing installations have bugs related to call connectivity algorithms that get addressed in later revisions.

5) Unable to make calls

If you have a giant “X” on your screen or are unable to make outbound calls, chances are you have two routers that drop certain critical packets of data.

This VoIP issue has less to do with your router configuration and more with the network layout.

Certain protocols are processed by the Application Layer Gateway (ALG) and rewritten for better flow through a firewall or NAT (Network Address Translation). However, it causes numerous problems for VoIP applications.

How to fix this VoIP issue:

To solve this VoIP problem, disable SIP ALG and avoid having double NAT or two routers inhibiting your flow of packets. Placing your VoIP phones on a VLAN can also help.

Disabling SIP ALG (TP-Link Archer A9).
Disabling SIP ALG is often as simple as unchecking a box. (TP-Link Archer A9).

6) Calls go to voicemail unexpectedly

It’s a big VoIP call quality problem when your phone doesn’t ring. But it’s a pretty simple fix! A possible setting was likely forgotten, or your phone is no longer registered with the VoIP provider.

You’ll also want to check that your phone is not in Do Not Disturb (DND) mode. You’ll know that this is the problem if a circle has a horizontal line inside it.

Review your current configuration for call forwarding and verify that all of your phones are registered and active.

7) One VoIP phone works but another doesn’t

If you’ve tested one phone and it isn’t working, but you try another device, and it is, chances are your VoIP Phone MAC address might not be registered or the configuration itself needs updating.

We recommend testing using a known working location and network port. If one phone works in both places and the other fails, it’s a problem with the phone.

If both phones work successfully at one location, it could suggest that an Ethernet drop is not functioning.

Otherwise, you must contact your VoIP service provider support for possible firmware or configuration updates.

You may need to replace your device if no updates are available and you’re still experiencing this issue.

8) Security breaches

VoIP systems may be vulnerable to security issues. Packet sniffing like man-in-the-middle attacks allows cybercriminals to eavesdrop on unencrypted calls routed over the internet.

VoIP systems have been compromised to rack up fraudulent international charges. The reason is that many VoIP providers do not include encryption by default.

How to stay clear of security breaches

Keep phones and systems fully patched and reset default passwords. Use VPN connections to secure sections of your network carrying VoIP traffic.

Also, make sure to pick a reliable VoIP phone service like Nextiva offering enhanced privacy with TLS & SRTP encryption and meeting security standards set by the ISO/IEC 27001 certification.

VoIP Troubleshooting Tips

When things go wrong, VoIP issues often feel daunting to diagnose and resolve.

Here are some basic first steps to troubleshoot common VoIP issues:

Related: How Does VoIP Work? The Beginner’s Guide To VoIP Phone Systems

Best Practices To Avoid VoIP Problems

While technical problems generally require technical solutions, following best practices helps avoid issues proactively.

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FAQs on VoIP Issues

What are the weaknesses of VoIP?

VoIP weaknesses include dependence on a broadband internet connection; emergency calls may fail if power or the internet is disrupted. Latency and jitter (if voice packets arrive inconsistently) also plague VoIP setups. Security is another concern if protocols are not properly implemented and kept updated.

What are VoIP issues?

A VoIP issue refers to any problem that affects the quality, reliability, or functionality of voice calls transmitted over the internet. Some common VoIP issues include:
– Choppy audio
– Call dropout
– Echo
– Latency/lag
– One-way audio
– Registration failures
– Number portability (porting and transferring phone numbers from traditional to VoIP networks)

How do I fix my VoIP problem?

Determine the root cause, prioritize VoIP traffic on the network, update hardware/software, optimize quality of service settings, or add bandwidth as needed to fix VoIP problems. Often it takes some troubleshooting to pinpoint the root cause. Maintenance is key to minimizing VoIP quality problems.

Cameron Johnson


Cameron Johnson

Cameron Johnson was a market segment leader at Nextiva. Along with his well-researched contributions to the Nextiva Blog, Cameron has written for a variety of publications including Inc. and Cameron was recently recognized as Utah's Marketer of the Year.

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