VoIP Call Quality Problems & How to Fix Them

VoIP call quality problems are almost always caused by one of a small number of network issues. The good news: once you identify the cause, the fix is usually straightforward. This guide covers every common VoIP call quality symptom, what causes it, and how to resolve it.

The Most Common VoIP Call Quality Problems

🔇 Choppy or Robotic Audio

What it sounds like: Caller's voice sounds like it's cutting in and out, breaking up, or robotic/digitised.

Cause: Almost always jitter — inconsistency in the delivery of data packets over the network. Voice data arrives in bursts rather than a steady stream, causing the audio to fragment.

Fixes:

• Enable QoS (Quality of Service) on your router — this prioritises VoIP traffic over other internet usage (downloads, streaming, video calls)
• Use a wired Ethernet connection for your desk phones rather than WiFi — wireless networks introduce variable latency
• Upgrade your router — consumer-grade routers handle QoS poorly; a business-grade router (Cisco, Netgear Pro) makes a significant difference
• Check for background bandwidth consumption — large file downloads or video streaming during calls consumes bandwidth and causes jitter

🔊 Echo

What it sounds like: You hear your own voice repeated back to you with a short delay, or the person you're calling hears their own echo.

Cause: Echo originates at the phone handset — either the speaker volume is too high (sound bleeds into the microphone) or the handset's acoustic echo cancellation isn't working correctly.

Fixes:

• Reduce the handset speaker volume by one or two notches — this is the most common and quickest fix
• Ensure the handset firmware is up to date — Yealink phones receive regular firmware updates that improve echo cancellation
• If using a headset, try a different headset — low-quality headsets with inadequate microphone shielding cause acoustic echo
• Check your Cloud X system settings — echo cancellation can be enabled/disabled at the extension level

🔕 One-Way Audio

What it sounds like: You can hear the caller but they can't hear you, or vice versa. One direction of the call is silent.

Cause: Almost always a firewall or NAT (Network Address Translation) issue. Your VoIP traffic is blocked in one direction — typically the return audio path — by a firewall rule or router configuration.

Fixes:

• Contact Telexico support — this is a configuration issue we can resolve on the server side or by adjusting your router settings
• Ensure SIP ALG (Application Layer Gateway) is disabled on your router — SIP ALG interferes with VoIP signalling and causes one-way audio on many router models
• Open UDP ports 5060 and 10000–20000 on your firewall if you have a custom firewall configuration

📵 Calls Dropping After a Few Minutes

What it sounds like: Calls connect normally but disconnect after 30 seconds, 2 minutes, or some other consistent interval.

Cause: Session timeout — your router is terminating idle sessions, or a firewall is closing the connection. The specific interval (30 seconds, 2 minutes) is often a clue to which device is causing it.

Fixes:

• Disable SIP ALG (see above)
• Increase your router's NAT timeout / UDP session timeout setting — set to 120 seconds or above
• Enable "keep-alive" packets in your Cloud X extension settings — this sends periodic traffic to keep the session open

⏱️ Delays and Latency

What it sounds like: There's a noticeable delay between speaking and the other person hearing you — the conversation feels "laggy."

Cause: High latency — data is taking too long to travel between your phone and the VoIP server.

Fixes:

• Check your broadband latency — run a speed test at fast.com and check the latency figure. Anything below 30ms is excellent; 30–80ms is acceptable; above 80ms will cause noticeable delay
• Switch from WiFi to wired Ethernet for phones — WiFi adds 5–20ms of latency compared to a wired connection
• Upgrade from FTTC to FTTP — full fibre broadband has lower and more consistent latency than copper-based connections

Quick Diagnostic Checklist

If you're a Telexico Cloud X customer and have tried the above without resolution, call our technical support team. We can remotely analyse your call quality logs and identify the root cause within minutes.