VoIP call quality problems are typically caused by network performance issues such as high latency, jitter, packet loss, or insufficient bandwidth. Because VoIP calls travel across internet networks as digital packets, unstable connectivity can cause audio delays, robotic voices, dropped calls, or missing audio.
Understanding these network factors helps businesses optimise their VoIP systems and ensure clear, reliable communication.
Why VoIP Call Quality Matters
Businesses depend on phone systems for:
- Sales conversations
- Customer support
- Internal communication
- Call centre operations
Poor call quality can result in:
- Frustrated customers
- Lost sales opportunities
- Inefficient support teams
Maintaining reliable VoIP call quality requires proper network design and stable internet connectivity.
Businesses should always use reliable business internet services when deploying VoIP systems. Explore connectivity solutions.
What is Latency?
Latency refers to the delay between sending and receiving voice packets during a VoIP call. When latency becomes too high, conversations start to feel delayed.
If latency is high, Person A speaks, there is a noticeable delay, and Person B hears the voice late. This creates overlapping conversations and awkward pauses.
Recommended Latency Levels
| Latency | Call Quality |
|---|---|
| Below 150 ms | Excellent |
| 150–300 ms | Acceptable |
| Above 300 ms | Poor |
High latency is often caused by congested networks, long routing paths, or unstable internet connections.
What is Jitter?
Jitter refers to variations in the time between voice packets arriving. VoIP packets should arrive at regular intervals, but network instability can cause packets to arrive unevenly.
Symptoms of Jitter
- Robotic voice
- Broken audio
- Inconsistent speech quality
Recommended Jitter Levels
| Jitter | Call Quality |
|---|---|
| Below 20 ms | Excellent |
| 20–50 ms | Acceptable |
| Above 50 ms | Poor |
Routers and VoIP systems often use jitter buffers to smooth packet delivery.
What is Packet Loss?
Packet loss occurs when voice packets fail to reach their destination. Since VoIP conversations are transmitted as packets, missing packets result in missing audio.
Symptoms of Packet Loss
- Words dropping out
- Choppy audio
- Broken conversations
Recommended Packet Loss Levels
| Packet Loss | Call Quality |
|---|---|
| Below 1% | Excellent |
| 1–3% | Noticeable |
| Above 3% | Poor |
Packet loss is often caused by overloaded networks, weak WiFi connections, or faulty network equipment.
Bandwidth Requirements for VoIP
VoIP calls require relatively small amounts of bandwidth, but stable connectivity is essential.
Using the G.729 codec, a typical VoIP call requires approximately 32 kbps upload and 32 kbps download per call.
However businesses should also allow additional bandwidth for:
- Network overhead
- Simultaneous calls
- Other internet traffic
For best performance, VoIP systems should run over business-grade fibre or licensed wireless connectivity. Explore business connectivity options.
How to Troubleshoot VoIP Call Quality Issues
Businesses experiencing VoIP problems should investigate the following factors:
1. Check Internet Connection Stability
Run latency and packet loss tests to evaluate network performance.
2. Monitor Bandwidth Usage
High network traffic can impact voice calls.
3. Enable Quality of Service (QoS)
QoS prioritises voice packets over other network traffic.
4. Use Wired Connections
VoIP phones perform better on Ethernet connections than WiFi.
5. Check Router Performance
Older routers may struggle to manage real-time voice traffic.
Best Network Practices for VoIP
Businesses deploying VoIP systems should follow several best practices:
- Use business-grade internet connectivity — Reliable connectivity reduces packet loss and latency.
- Implement QoS policies — This ensures voice traffic receives priority.
- Monitor call quality metrics — Tools such as MOS scoring help detect call quality issues.
- Deploy professional network infrastructure — Enterprise-grade routers and switches improve VoIP stability.
SureTel VoIP Solutions
SureTel provides reliable VoIP services designed for South African businesses. Our solutions include:
- VoIP phone systems
- Cloud PBX platforms
- SIP trunking
- Call centre infrastructure
Learn more about our VoIP Solutions or explore Business VoIP for South Africa.