Choppy or Robotic Audio on VoIP Calls: How to Fix It

What Causes Choppy or Robotic Audio?

Choppy, robotic or breaking audio on VoIP calls is caused by voice data packets being lost, delayed or arriving out of order. When packets are missing, your phone cannot reconstruct the audio properly, resulting in gaps, stuttering or a robotic, metallic sound.

This is different from echo or one-way audio — with choppy audio, both parties can hear each other, but the sound quality is poor and words are broken up or distorted.

Common Causes

1. Packet Loss

Packet loss is the primary cause of choppy audio. When voice packets are dropped during transmission, the audio has gaps. Even 1% packet loss is noticeable on VoIP calls, and anything above 3% makes calls unusable.

Packet loss can occur anywhere along the network path — on your local network, at your router, on your broadband connection, or on the internet between you and your VoIP provider.

2. Insufficient Bandwidth

Each VoIP call requires approximately 100 kbps of bandwidth in each direction (using G.711 codec). If your internet connection is saturated by other traffic — large file downloads, cloud backups, video streaming, software updates — there is not enough bandwidth left for voice traffic, and packets get dropped or delayed.

This is especially common on connections with limited upload speed. Many broadband connections have asymmetric speeds (e.g. 80 Mbps download but only 20 Mbps upload), and the upload is often the bottleneck.

3. Wi-Fi Interference

Using VoIP phones over Wi-Fi is a common cause of choppy audio. Wi-Fi is inherently less reliable than wired Ethernet due to:

Interference from other Wi-Fi networks, microwaves, Bluetooth devices
Signal degradation through walls and distance from the access point
Contention — Wi-Fi is a shared medium where devices take turns transmitting
Roaming — if a device switches between access points, packets can be lost during the handover

4. QoS Not Configured

Without Quality of Service (QoS) configured on your router, voice traffic competes equally with all other data traffic. During periods of high network usage, voice packets may be queued behind large data transfers, causing delays and packet loss.

5. Too Many Concurrent Calls

If you have more simultaneous calls than your internet connection can support, all calls will suffer quality degradation. Calculate your maximum concurrent calls based on your available bandwidth:

10 Mbps upload — supports approximately 100 concurrent G.711 calls (in theory), but allow 50% headroom, so plan for 50 calls maximum
1 Mbps upload — supports approximately 10 concurrent calls with headroom

Diagnosing the Problem

Run a Speed Test

Test your internet speed at speedtest.net during business hours when the problem occurs. Pay particular attention to:

Upload speed — this is usually the limiting factor
Consistency — run the test multiple times; if results vary wildly, your connection is unstable

Test Wi-Fi vs Wired

If your phones are on Wi-Fi, temporarily connect one to wired Ethernet and compare call quality. If the wired phone sounds clear while the Wi-Fi phone is choppy, Wi-Fi is the culprit.

Monitor Packet Loss

Run a sustained ping test to your VoIP provider's server:

On Windows: ping -n 200 your-sip-server.com
On Mac/Linux: ping -c 200 your-sip-server.com

Check the results for packet loss percentage and latency variation. Any packet loss above 0% warrants investigation.

Check for Bandwidth Hogs

Log into your router and check which devices are consuming the most bandwidth. Common culprits include:

Cloud backup services (OneDrive, Google Drive, Dropbox syncing large files)
Windows Update downloading across multiple PCs simultaneously
Video conferencing on other devices
Streaming services

Fixes for Choppy Audio

Fix 1: Use Wired Ethernet, Not Wi-Fi

This is the single most impactful fix. Always connect VoIP phones via wired Ethernet, never Wi-Fi. IP desk phones have Ethernet ports built in. If you use softphones on laptops, connect the laptop to Ethernet during calls or use a high-quality Wi-Fi 6 connection with minimal interference.

Fix 2: Enable QoS on Your Router

Configure your router to prioritise voice traffic. Set up QoS rules to give priority to traffic on UDP ports 5060 (SIP) and 10000–20000 (RTP). This ensures voice packets are sent first, even when the network is busy. See our network configuration guide for QoS setup details.

Fix 3: Reduce Concurrent Calls

If you are exceeding your bandwidth capacity, either reduce the number of simultaneous calls or upgrade your broadband. You can also switch to a lower-bandwidth codec like G.729 (8 kbps vs 64 kbps) to fit more calls on the same connection. See our codec guide.

Fix 4: Upgrade Your Broadband

If your connection simply does not have enough bandwidth or is unreliable, consider upgrading to:

FTTP (Fibre to the Premises) — symmetrical speeds, low latency
Leased line — dedicated, guaranteed bandwidth with an SLA
Business broadband — often prioritised over residential traffic

Fix 5: Separate Voice on a Dedicated VLAN

Create a dedicated voice VLAN on your network switch to isolate phone traffic from data traffic. This prevents data traffic spikes from affecting call quality and makes QoS policies easier to apply.

Still Experiencing Issues?

If choppy audio persists after implementing these fixes, the issue may be outside your network — on your ISP's network or your VoIP provider's infrastructure. Contact our team for a detailed network assessment and we can help identify the root cause.