SureTel
VoIP bandwidth guide
VoIP Bandwidth & Internet Requirements
Plan business VoIP around call quality, upload speed, simultaneous calls and reliable connectivity.
- • Business VoIP and Cloud PBX
- • Connectivity-aware voice planning
- • QoS, network and failover guidance
- • South African business support
Educational resource · Not a quote · Licensed SA ISP · ICASA licence 0009/CECS/AUG/09
Answer first
VoIP bandwidth, in one paragraph
VoIP bandwidth should be planned around simultaneous calls, upload capacity and call quality rather than download speed alone. SureTel assesses your users, call volume, internet link, router/firewall, Wi-Fi, QoS, failover and Cloud PBX needs before recommending a practical VoIP setup for South African businesses. Request VoIP Pricing to scope the right connection and configuration.
Summary
- • Plan bandwidth by simultaneous calls, not total users.
- • G.711 needs about 87.2 kbps per call each way, overhead included.
- • G.729 needs about 31.2 kbps; Opus (32 kbps payload) about 55.2 kbps.
- • Latency, jitter, packet loss, Wi-Fi and QoS affect call quality.
- • Request VoIP Pricing or call SureTel.
See business VoIP services for commercial detail.
Free tool
VoIP bandwidth calculator
Enter how many calls you expect at the same time and the codec your phones use. The calculator shows the upload and download your calls need, then adds headroom and any other internet use on the same line.
Your result
For 10 simultaneous G.711 calls you need about 1.1 Mbps up and down with 20% headroom, before other internet use.
- Calls alone — upload
- 0.872 Mbps
- Calls alone — download
- 0.872 Mbps
- Total upload (headroom + other use)
- 1.046 Mbps
- Total download (headroom + other use)
- 1.046 Mbps
How we calculate this
Per-call bandwidth = (voice payload per packet + 40 bytes IP/UDP/RTP + 18 bytes Ethernet) × 8 bits × 50 packets per second.
Total per direction = simultaneous calls × per-call bandwidth × (1 + headroom %) + other internet use.
- • 20 ms packetisation (50 packets per second each way).
- • IP/UDP/RTP and Ethernet overhead included; no VPN, tunnel or Wi-Fi overhead.
- • Symmetric: every call sends and receives the same amount, so upload and download match.
- • G.711 87.2 kbps, G.729 31.2 kbps and Opus at a 32 kbps payload about 55.2 kbps per call, each direction.
- • A planning estimate, not a guarantee — real usage depends on your phones, PBX and network.
Next step, if it helps: see how business fibre handles voice and data together, or check what your address can get.
This calculator runs in your browser and doesn't store or send anything you enter.
Cite or link to this calculator: https://suretel.co.za/resources/voip-bandwidth-requirements
When it fits
When bandwidth planning matters most
Small offices may only need simple checks, while reception teams, call centres and multi-branch businesses need more deliberate voice planning. The higher the call volume, the more important upload capacity, QoS and failover become.
- Reception and switchboard teams.Frequent inbound and transferred calls need stable voice quality.
- Sales and support teams.Multiple simultaneous outbound calls require reliable upstream bandwidth.
- Call centres.Concurrent agent calls need dedicated planning, monitoring and failover.
- Cloud PBX users.Desk phones, mobile apps and softphones depend on network quality to reach the hosted platform.
- WebRTC users.Browser calling may add extra bandwidth and device-dependence compared with standard desk-phone calling.
- Multi-branch businesses.Each branch should be assessed independently because links, routers and Wi-Fi differ.
- Remote and hybrid teams.Home and mobile networks may need separate expectations and user guidance.
Problems this solves
Why VoIP call quality is not only about internet speed
A fast internet line can still produce poor VoIP calls if upload capacity, latency, jitter, packet loss, Wi-Fi or router performance is weak. That's the difference between raw speed and voice readiness — and it's worth understanding before you buy.
Calls break up on a fast line
The line may have enough download speed but poor upload, jitter or packet loss.
Too many simultaneous calls
Bandwidth should be calculated by concurrent calls, not by total extensions.
Router or firewall overload
Voice can suffer when a router, firewall or NAT setup cannot handle traffic cleanly.
No QoS or voice prioritisation
Downloads, cloud backups, CCTV uploads or updates can compete with voice packets.
Weak Wi-Fi for softphones
Softphones and mobile apps can perform poorly on congested or low-quality Wi-Fi.
No power or internet fallback
VoIP depends on powered equipment and a working internet connection.
Wrong failover choice
LTE/5G can work well in the right conditions, but fixed backup is often better for larger or business-critical environments.
Use cases
VoIP bandwidth examples by business type
Find the setup closest to yours and note what to plan for.
Small office with a few calls
Needs stable upload, router readiness and basic failover planning.
Reception-heavy business
Needs reliable voice during busy inbound periods and call-transfer workflows.
Sales or support team
Needs enough concurrent-call capacity and QoS so calls do not compete with normal office internet usage.
Call centre
Needs dedicated capacity planning for concurrent agent calls, router/firewall design, monitoring and failover.
Multi-branch business
Needs each site checked for link quality, local network readiness and consistent voice performance.
Remote and hybrid teams
Need softphone/mobile app expectations, user-device guidance and stable home or business-managed connectivity.
LTE/5G failover voice site
Can work for 30 or more concurrent calls where the LTE/5G service is dedicated to voice and signal/network quality is strong, but a fixed uncapped backup connection is usually better where available.
Cloud PBX with WebRTC users
Needs normal voice-media planning plus additional consideration for browser calling, devices and web access.
Quality factors
What affects VoIP bandwidth and call quality?
VoIP sends voice as network packets. Bandwidth is only one part of the design; the call also needs low delay, stable timing and minimal packet loss.
| Factor | Plain-English meaning | Why it matters |
|---|---|---|
| Simultaneous calls | How many calls happen at the same time | Bandwidth is consumed by concurrent calls, not dormant extensions. |
| Codec | The voice compression method | G.711 uses more bandwidth; compressed codecs use less but may have quality or compatibility trade-offs. |
| Upload speed | Outbound capacity from the business site | Every call sends voice out as well as receiving voice in. |
| Download speed | Inbound capacity to the business site | Incoming audio still needs clean download capacity. |
| Latency | Delay between speaker and listener | High delay makes conversation feel unnatural. |
| Jitter | Variation in packet arrival timing | High jitter can cause choppy or robotic audio. |
| Packet loss | Packets that never arrive | Lost packets can cause missing audio or broken speech. |
| Router/firewall | Network device handling traffic | Poor NAT, overloaded hardware or wrong settings can hurt voice quality. |
| QoS/voice prioritisation | Prioritising voice traffic over less urgent traffic | Helps protect calls when the link is busy. |
| Wi-Fi quality | Wireless signal and congestion | Softphones and mobile apps can suffer on weak or busy Wi-Fi. |
| Power continuity | UPS for routers, switches, ONTs/CPEs and phones | Voice equipment stops if essential devices lose power. |
| Failover path | Backup internet route | Keeps calls working when the primary line fails, if designed for the call load. |
SureTel can assist with internet speed checks, upload capacity, router/firewall setup, QoS/voice prioritisation, cabling, Wi-Fi, PoE, network readiness, full network installations and ongoing network maintenance where required.
Cost guidance
What affects the cost of making your internet VoIP-ready?
These are the practical cost factors that can affect a business voice recommendation; VoIP and connectivity pricing is quoted per service and address.
| Cost factor | Why it matters |
|---|---|
| Number of simultaneous calls | More concurrent calls require more dedicated voice capacity and better quality control. |
| Current internet service | A site may already have enough bandwidth, or it may need fibre, wireless, microwave or another business-grade option. |
| Router/firewall readiness | Some routers need configuration, replacement or better traffic handling. |
| LAN and cabling | Poor cabling, old switches or no PoE can affect desk-phone deployments. |
| Wi-Fi design | Softphones and mobile apps may need stronger Wi-Fi coverage and capacity. |
| Backup connectivity | Business-critical voice may need a reliable failover path sized for the expected call load. |
| UPS backup | Router, firewall, switch, ONT/CPE and phone power should be planned together. |
| WebRTC usage | Browser-based calling may need additional planning for users, devices and connection quality. |
| Multi-site environments | Each branch may need a separate readiness check and support model. |
Request VoIP Pricing and include your user count, sites, current internet service and estimated simultaneous calls. See business connectivity and business fibre for connection options.
Planning guide
How much bandwidth does VoIP need?
Use this as a planning guide only. Actual results depend on codec, packet size, provider configuration, firewall/router behaviour, internet contention, VPNs, Wi-Fi quality and whether calls use desk phones, softphones or WebRTC.
Planning table — voice bandwidth per direction, before headroom
| Simultaneous calls | G.711 at 87.2 kbps per call | G.729 at 31.2 kbps per call | Opus (32 kbps payload) at 55.2 kbps per call | Practical planning note |
|---|---|---|---|---|
| 5 calls | 0.436 Mbps | 0.156 Mbps | 0.276 Mbps | Add headroom for signalling, other traffic and link variation. |
| 10 calls | 0.872 Mbps | 0.312 Mbps | 0.552 Mbps | Suitable upload capacity matters as much as download capacity. |
| 20 calls | 1.744 Mbps | 0.624 Mbps | 1.104 Mbps | Use QoS and avoid sharing voice with heavy unmanaged traffic. |
| 30 calls | 2.616 Mbps | 0.936 Mbps | 1.656 Mbps | LTE/5G can work if dedicated and signal/network quality is strong, but fixed backup is better where feasible. |
| 50 calls | 4.360 Mbps | 1.560 Mbps | 2.760 Mbps | Plan with proper headroom, failover and network monitoring for business-critical voice. |
- • These are bandwidth planning estimates, not guaranteed performance figures.
- • Figures are per direction for the calls alone, at 20 ms packetisation with IP/UDP/RTP and Ethernet overhead — the same maths as the calculator above. Add headroom on top.
- • Compressed codecs can reduce bandwidth, but call quality, compatibility, transcoding and platform policy must be checked.
- • Always plan both upload and download.
- • Do not size a business link only to the raw voice number; allow headroom for other business traffic, peak usage and network variation.
- • Teams meetings, video calls, screen sharing and general cloud app traffic are separate from standard business VoIP calling.
Decision table — connection and backup fit
| Scenario | Better option | Watch-outs |
|---|---|---|
| Small office with light calling | Existing stable business internet may be enough | Check upload, router and Wi-Fi quality. |
| Office with many desk phones | Business fibre, wireless or microwave where feasible | Need cabling, PoE, QoS and UPS planning. |
| Call centre or high-call-volume team | Dedicated voice-ready connectivity and suitable failover | Avoid relying on contended or unmanaged links. |
| LTE/5G backup for voice | Can work if dedicated to voice, with strong signal and enough data/capacity | Not ideal if shared with heavy data, CCTV or general internet usage. |
| Larger site needing resilience | Fixed uncapped backup connection where feasible | Usually better for predictable capacity and ongoing failover usage. |
| Cloud PBX with WebRTC | Strong LAN/Wi-Fi, stable devices and browser/device readiness | WebRTC can add user-device and browser-quality variables. |
See business connectivity, business fibre, wireless internet, licensed microwave and LTE/5G backup for connection and failover options, and business VoIP services for commercial detail.
Educational
What is VoIP bandwidth?
VoIP bandwidth is the amount of internet capacity used to carry voice packets between phones, apps, PBX platforms and the outside telephone network. Each active call uses bandwidth in both directions, and the exact amount depends on codec, packet overhead and call setup. At 20 ms packetisation with overhead, a call uses about 87.2 kbps each way on G.711, 31.2 kbps on G.729 and about 55.2 kbps on Opus at a 32 kbps payload — these figures are estimates, not guarantees, because codec settings, packet size, provider setup, router behaviour and network conditions can change real usage.
Per-call usage
Each active call consumes capacity while the call is live.
Concurrent calls
A business with 50 extensions may only need capacity for the number of calls active at the same time.
Upload and download
Voice travels both ways, so upstream quality is important.
Codec overhead
The audio codec is only part of the calculation; network headers and transport overhead also add to usage.
Cloud PBX context
Standard call recording on SureTel Cloud PBX happens at the data-centre/PBX level and should not add extra customer-site bandwidth for recording itself.
Web access and WebRTC
The Cloud PBX web GUI has its own minimal access needs, while WebRTC/browser calling must be planned separately where used.
For a plain-English VoIP introduction, see what is VoIP? For device and network hardware context, see the VoIP equipment guide; for softphone vs desk phone choices, see softphones vs desk phones. For deeper codec detail, see VoIP codecs explained.
Why SureTel
Why ask SureTel about VoIP bandwidth?
VoIP performance is affected by voice service, Cloud PBX configuration, internet connection, local network design and support. SureTel can help align these parts instead of treating voice and connectivity as separate problems.
VoIP and Cloud PBX context
Guidance can account for extensions, call flow, call volume, WebRTC and PBX usage.
Connectivity options
SureTel can provide business fibre, wireless internet, licensed microwave and backup connectivity where feasible.
Network readiness
SureTel can assist with cabling, PoE, Wi-Fi, router/firewall setup, QoS and voice prioritisation.
Full network installations and maintenance
Included as a practical capability where required for voice readiness.
Failover planning
SureTel can help choose backup connectivity based on call load, risk and site feasibility.
Practical support
A clear point of contact for the supplied VoIP and connectivity environment, within the scope of the solution.
SureTel does not promise perfect call quality, guaranteed uptime, or uninterrupted service during all power or connectivity failures. Guidance uses “can assist”, “where feasible”, “subject to signal/network quality”, and “depends on configuration and site conditions”. Related services: business VoIP, Cloud PBX and business connectivity.
Process
How VoIP bandwidth planning works
Keep this process simple and operational — the goal is to show buyers what information SureTel needs before recommending VoIP and connectivity options.
- Step 1
Confirm users and call volume
Estimate total users, extensions and likely simultaneous calls.
- Step 2
Review current internet
Check primary line type, speed, upload capacity, contention and stability.
- Step 3
Check quality indicators
Review latency, jitter, packet loss and real-world call symptoms where possible.
- Step 4
Assess the local network
Review router/firewall, cabling, switches, PoE, Wi-Fi and QoS readiness.
- Step 5
Plan voice traffic
Match codec, phones, softphones, Cloud PBX and WebRTC requirements to the environment.
- Step 6
Plan backup and power
Consider UPS and a failover path sized for the expected voice load.
- Step 7
Quote and implement
Recommend VoIP pricing, connectivity or network work where required.
- Step 8
Test and support
Test calls, refine configuration and support the supplied solution scope.
Not sure whether your internet is ready for VoIP?
Request VoIP Pricing and include your user count, sites, current internet service and estimated simultaneous calls.
FAQs
VoIP bandwidth FAQs
How much bandwidth does one VoIP call use?
At 20 ms packetisation, including IP/UDP/RTP and Ethernet overhead, one call uses about 87.2 kbps each way on G.711, 31.2 kbps on G.729 and about 55.2 kbps on Opus at a 32 kbps payload. These figures are estimates, not guarantees, because codec settings, packet size, provider setup, router behaviour and network conditions can change real usage.
Should I calculate VoIP bandwidth by users or simultaneous calls?
Calculate by simultaneous calls. A business might have 50 extensions but only 10 or 20 active calls at the same time. Dormant phones or users do not consume the same voice bandwidth as live calls, although devices, apps and PBX access can create small background traffic.
Is upload speed important for VoIP?
Yes. VoIP sends voice out from your business as well as receiving voice in, so upload speed and upload quality are critical. A connection with strong download speed but weak upload, high jitter or packet loss can still produce poor voice quality.
Why are VoIP calls bad on a fast internet connection?
A fast connection can still have poor VoIP quality if latency, jitter, packet loss, Wi-Fi instability, router overload, firewall problems or unmanaged traffic are present. VoIP needs consistent packet delivery, not only a high speed-test result.
Does VoIP work on LTE or 5G?
Yes, LTE or 5G can work for VoIP when signal quality, network capacity and router setup are strong. In SureTel’s practical experience, dedicated LTE/5G can support 30 or more concurrent calls if the connection is used only for voice and the area network supports it. A fixed uncapped backup connection is usually better where feasible.
Is fibre the best internet for VoIP?
Business fibre is often a strong option for VoIP because it can provide stable capacity and lower latency where available, but it is not the only option. Wireless internet, licensed microwave and dedicated LTE/5G can also be suitable in the right conditions. The best option depends on feasibility, site risk, call volume and backup needs.
Does call recording use extra internet bandwidth?
For SureTel Cloud PBX, call recording is handled at the Cloud PBX/data-centre level, so standard call recording does not add extra customer-site bandwidth for the recording itself. The customer site still needs normal bandwidth for the live call audio. The Cloud PBX web GUI and WebRTC, where used, should be planned separately.
Does Cloud PBX need extra bandwidth?
Cloud PBX calling uses bandwidth for the live voice traffic between the user’s phone, app or browser and the hosted PBX environment. The web management interface has separate access needs, usually light. WebRTC/browser calling can add additional device, browser and bandwidth considerations, especially for remote users.
Do I need QoS for VoIP?
QoS or voice prioritisation is strongly recommended when voice shares the same network or internet connection with normal business traffic. It helps prioritise voice packets over less time-sensitive traffic such as downloads, backups or software updates. QoS must be configured correctly on suitable network equipment.
What internet backup do I need for VoIP?
The right backup depends on call volume, business risk, site feasibility and whether the backup is dedicated to voice. LTE/5G can work well for dedicated voice fallback where signal and capacity are strong, including larger concurrent-call counts in the right conditions. For larger or more critical environments, a fixed uncapped backup connection is usually better.
Next step
Need help checking whether your internet is ready for VoIP?
SureTel can help you plan VoIP around simultaneous calls, internet quality, local network readiness, QoS, Cloud PBX usage and backup connectivity.
Educational resource · Not a quote · VoIP call quality and continuity depend on network, power, configuration and backup. Bandwidth figures on this page are planning estimates, not guaranteed performance. Request VoIP Pricing for a scoped recommendation.