Key Takeaways:
Allocate 100 kbps per active VoIP call—but factor in your full network needs.
Fibre is best for consistent quality and growth, especially with 10+ agents.
Wireless is a backup, not a core solution for a VoIP contact centre —except in remote areas.
Optimise your network with QoS, VLANs, and business-grade routers.
Always test your speeds under real-world conditions, not just speed test tools.
A VoIP contact centre is only as good as the internet connection it runs on. Poor call quality, dropped connections, jitter, and lag can all disrupt customer service and impact your brand’s reputation.
So what internet speed do you really need for a high-performing VoIP contact centre?
In this guide, we’ll break down how bandwidth works, how to calculate requirements per user, and whether you should opt for fibre or wireless internet. Whether you’re running a five-agent team in Pretoria or a 100-seat call centre in Johannesburg, you’ll walk away with practical, answers.
Understanding VoIP and Bandwidth Basics
Voice over IP (VoIP) converts voice into data packets that travel over the internet. This means your voice calls compete for bandwidth alongside email, browsing, video calls, and cloud software—especially in a busy contact centre.
Key Definitions:
Bandwidth: The volume of data that can be transmitted over your internet connection (measured in Mbps).
Latency: The time it takes for a data packet to travel from one point to another (measured in ms).
Jitter: Variability in packet arrival time—high jitter = poor call quality.
Packet Loss: Data lost in transmission—results in robotic voices or dropouts.
To ensure high call quality in your VoIP contact centre, you need enough dedicated bandwidth, low latency, and minimal jitter.
How Much Bandwidth Does a VoIP Call Use?
The bandwidth needed per VoIP call depends on the codec used (how voice data is compressed).
| Codec | Quality | Bandwidth per Call (kbps) |
|---|---|---|
| G.711 (Uncompressed) | High (PSTN quality) | ~100 kbps |
| G.729 (Compressed) | Good | ~30–40 kbps |
| Opus (Dynamic) | Excellent | ~40–100 kbps |
Don’t Forget Non-VoIP Traffic
Why it matters for your VoIP Contact Centre:
Many readers calculate bandwidth per call but forget about other network usage like CRMs, file uploads, Microsoft Teams, CCTV streams, etc.
What to cover:
Estimating total usage across departments
Why isolating VoIP traffic with VLANs helps
Example of a miscalculated scenario and what went wrong
Example:
If you have 20 active agents making simultaneous calls using G.711, your VoIP traffic alone will need:
20 x 100 kbps = 2 Mbps up and 2 Mbps down
But that’s just for voice. You’ll also need overhead for:
CRM tools
Browsing
Cloud software
Email & internal comms
Shared vs Dedicated Internet Lines
Why it matters for your VoIP Contact Centre:
Many businesses don’t realise how much shared bandwidth (e.g., basic fibre packages or wireless with contention ratios) can impact VoIP performance. Educating them on dedicated business fibre vs shared consumer-grade lines adds real value.
What to cover:
Contention ratios (e.g. 10:1 vs 1:1)
Why dedicated fibre ensures stability for larger teams
How to ask ISPs about uncontended services
Recommended Internet Speeds by Contact Centre Size
| Contact Centre Size | Min Internet Speed (Symmetrical) | Ideal Setup |
|---|---|---|
| 1–10 agents | 10 Mbps | Fibre or dedicated wireless |
| 11–50 agents | 20–50 Mbps | Fibre with QoS routing |
| 50+ agents | 100 Mbps+ | Fibre with redundant failover links |
VoIP Bandwidth Requirements by Team Size
| Team Size | Codec Used | Bandwidth per Call | Estimated Concurrent Calls | Required Bandwidth (Upload/Download) |
|---|---|---|---|---|
| 5 Agents | G.711 | 100 kbps | 3–5 | 0.5 – 1 Mbps |
| 15 Agents | G.729 | 40 kbps | 10–12 | 0.5 – 1 Mbps |
| 30 Agents | G.711 | 100 kbps | 25 | 2.5 Mbps |
| 60 Agents | G.729 | 40 kbps | 50 | 2 – 2.5 Mbps |
| 100 Agents | G.711 | 100 kbps | 80 | 8 Mbps |
Fibre vs. Wireless Internet: Which Is Better?
🌐 Fibre (Recommended)
Pros:
Symmetrical upload/download speeds
Low latency and jitter
Stable during peak usage
Future-proof
Cons:
Availability may be limited in rural or new areas
Installation lead times
Top SA Providers: Vumatel, Openserve, Frogfoot, MetroFibre, Octotel
📡 Wireless (Fixed LTE/5G)
Pros:
Faster deployment
Flexible for temporary or mobile contact centres
Cons:
Asymmetrical speeds (slower uploads)
Susceptible to interference/weather
Performance drops during high network congestion
Top SA Providers: Rain (5G), MTN Business, Vodacom LTE Business, Herotel
💡 Conclusion: Fibre is the gold standard for reliability and scalability. Wireless can work for smaller teams or backup connections, but it’s riskier for high-volume centres.
Wireless Options: When and How to Use Them
Why it matters for your VoIP Contact Centre:
Many South African areas still rely on fixed LTE or 5G. This section can dive into realistic use cases, how to make wireless more viable (external antennas, dual WAN setup), and where it fits best.
What to cover:
Fixed LTE vs 5G vs microwave
Backup vs primary use
Wireless signal management tips
Tips to Optimise VoIP Contact Centre Performance
✅ Prioritise VoIP traffic using QoS (Quality of Service) settings on your router.
✅ Use dedicated VoIP VLANs to separate voice traffic from general usage.
✅ Invest in business-grade routers that support packet prioritisation.
✅ Monitor internet usage to avoid oversaturation (especially in hybrid teams).
✅ Always test your connection during peak business hours, not just off-peak.
Real-World Scenario: A Johannesburg SME
Company: A legal services provider in Johannesburg with 15 call agents.
Internet Package: 100 Mbps fibre (symmetrical)
Setup: G.729 codec with softphones + CRM system
Performance: Zero call drops in 6 months, improved response time by 20%
“We switched from LTE to fibre and saw a massive difference. Our call quality is crystal clear, and staff productivity is up.” – Operations Manager
When it comes to running a reliable VoIP contact centre, your internet connection is just as critical as your headsets and software. While 100 kbps per call is the minimum rule of thumb, real-world performance depends on your total user load, how often calls overlap, and what else is using your connection.
If you’re serious about uptime, fibre remains the gold standard—offering speed, stability, and room to grow. But don’t count wireless out entirely; for smaller or mobile setups, fixed-LTE or 5G can be surprisingly capable with proper QoS (Quality of Service) settings and enough redundancy.
Take time to audit your usage, consult your provider, and consider upgrading if your agents are still saying “Hello? Can you hear me now?” too often.
