7 Common VoIP Problems: Causes and How to Troubleshoot Them

 VoIP Problems Causes

The transformative technology of Voice over Internet Protocol (VoIP) has truly revolutionized the business world. It offers advanced features and numerous advantages over traditional PBX and analog phones. However, like none of the technological innovation is devoid of some challenges; so is VoIP. This blog post addresses some of the common VoIP problems and solutions so users can navigate through the intricacies of VoIP.

Choppy Voice / Poor Call Quality

This is one of the most commonly faced VoIP issues. The calls are not completely disconnected, but there are pauses, certain words are dropped and voices keep cutting in and out. Imagine this happening during an important discussion or meeting with a client. Therefore, businesses need to handle this VoIP issue as soon as possible.     


  • Common contributing factors for choppy voice and poor call quality include slow internet connection and network congestion. 
  • Network congestion is when there is excessive network traffic leading to delay and packet loss. 
  • This may also be a codec-related issue. Codec compresses and decompresses audio data during transmission. If these are not properly configured, it impacts the audio quality and choppy voice.


Ensure reliability of your Wi-Fi connection – a poor internet connection is a major reason for poor call quality. Consider switching to an Ethernet internet connection.

  • Minimize network congestion – try to limit the number of users engaging in data-demanding activities. By data-demanding activities, we are referring to live streaming, games, video conferencing, and so on.  
  • Ensure VoIP QoS – check your router setting and make sure to prioritize VoIP QoS. Even when the local network is crowded, your router will prioritize VoIP and provide adequate bandwidth.

Frequent Call Dropping

Call dropping disrupts conversation, and hinders business operations and overall productivity. Generally, this VoIP issue problem is reported during outbound calls when the connection is disrupted and the call disconnects unexpectedly.    


  • Connectivity issue – Call dropping may happen due to insufficient bandwidth and poor connectivity.
  • Outdated firmware – make sure to have updated firmware – a program embedded in VoIP hardware devices for smooth functioning.     
  • UDP timeout – user datagram protocol (UDP) timeout is the maximum duration for which a UDP route stays open on a firewall or router. By default, the timeout duration is 30 seconds, after which there may be firewalls closing the connection resulting in unexpected call termination. You can go to the router setting and set the duration to 60 seconds to mitigate the mentioned VoIP problem.

Jitter And Latency Issues

VoIP jitter is when the data packet is delayed during transmission from the caller end to the recipient. This issue happens when parts of audio data are sent to the recipient in an unorganized manner, resulting in nonsensical conversation.

VoIP jitter further causes latency issues when the caller’s voice takes some time to reach the recipient’s end. Ideally, VoIP jitter should not exceed 15-20 milliseconds.


  • SIP ALG – SIP Application Layer Gateway (ALG) is the default configuration on commercial routers. Disabling this feature can help in VoIP troubleshooting.
  • Double NAT (Network Address Translation) – Network address translation (NAT) provides a private IP address to all the devices in your network. However, if there happens to be more than one device providing NAT, this leads to VoIP jitter and latency.
  • Install jitter buffer – when installed on a VoIP phone system, the jitter buffer slightly delays the data packet delivery. This way the data packets are transmitted in real time and orderly manner.

Audio Distortion And Echo

Phone echo occurs when voices loudly repeat at varying intervals during a call. Acoustic echo is when sound reflects on surfaces and returns to the microphone, which makes it difficult to understand what is being said.


  • In most cases, echo is related to hardware issues, defective equipment, and placement of VoIP phones.
  • There might be defects in devices, headsets, and VoIP equipment.
  • Electromagnetic interference – this happens if the VoIP device is placed close to another electronic device.


  • Make sure to repair or replace any defective device; headset, speakerphone, etc.
  • Reduce electromagnetic interference and do not place VoIP phones near bulky electronic devices as both will have strong electric fields, which impacts VoIP quality.

Unable To Make Or Receive Call

Users sometimes face this VoIP problem where VoIP phones won’t make or receive calls.  This is when VoIP phones not working but internet is. VoIP phone system either fails to connect outbound calls or does not register inbound calls.


In most cases, this VoIP issue happens due to SIP ALG, NAT, and sometimes outdated VoIP software.


  • Turn off SIP ALG – disable SIP ALG from your router’s menu. The SIP ALG ideally modifies a network’s outbound VoIP packets for smooth transmission through firewalls. However, sometimes the data packets fail to reach the recipient end because they get transmitted to the wrong IP address.
  • VoIP software update – update VoIP software and reboot the device for VoIP troubleshooting.

Unable To Hear The Voice After Call Connection  

Sometimes there is no issue with call connectivity. However, after the call is connected, either one or both users cannot hear anything.


  • Calls connected with no sound are the result of a firewall blocking the real-time transport protocol (RTP). RTP is a network protocol that is responsible for the transmission of audio and video data packets. When blocked, it leads to VoIP calls with no sound.
  • Sometimes if there are incompatible codecs of both VoIP devices, it also impacts call quality.    


  • Disable SIP ALG – disabling SIP ALG is useful for VoIP troubleshooting in most cases. This is because when disabled, SIP ALG opens ports and allows a smooth flow of traffic.
  • Also, make sure that both phones and devices share common codecs.

Bottom line of VoIP problems

VoIP problems can adversely impact the quality of VoIP calls, which further impacts the continuity of core business operations. Therefore, time and prompt VoIP troubleshooting are crucial for users to ensure seamless connectivity. Replacing and repairing defective equipment, router configuration, encryption, and regular software updates are some common ways of VoIP troubleshooting.

Most importantly, users must stay informed about the latest advancements in VoIP technology and must implement them. Moreover, seeking professional guidance is another to resolve VoIP problems so you may continue to enjoy reliable and affordable connectivity.

Frequently Asked Questions (VoIP problems)

How can I troubleshoot one-way audio issues during a call?

One-way audio during VoIP calls is mostly related to NAT traversal issues. Network address translation (NAT) is the technique of establishing internet protocol connections across a gateway. You can resolve this issue by checking NAT configuration, and firewall settings, and disabling SIP ALG (application layer gateway) in your router.

How to fix the no-sound issue in VoIP calls?

Such an issue often arise due to firewall setting that blocks RTP packets (real-time transfer protocol). This issue can be resolved by disabling SIP ALG.

What are the potential causes of latency and how to fix this?

Network congestion due to insufficient bandwidth or long-distance data travel often results in latency and poor call quality. To resolve this issue, make sure to have a stable internet connection, and sufficient bandwidth, and ensure proper quality of service QoS configuration.

Why am I facing broken audio and jitters?

Muffled voice and jitter is an issues related to insufficient bandwidth. During a call, data packets are lost resulting in such an issue.  Make sure to have a stable internet connection with sufficient bandwidth to improve VoIP call quality.

VoIP phone is not registering with the service provider; what can be the potential reason for this?

This problem is often linked to incorrect credentials and firewall settings. You can troubleshoot by checking your login details and verifying the router setting. If the issue persists, you should contact your service provider as their support team will assist you.    

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