Call Centre • Bandwidth planning

What internet speed does a VoIP contact centre need?

A practical guide to sizing bandwidth for a VoIP contact centre: per-call maths, the overhead everyone forgets, and whether fibre or wireless should carry your calls.

Last verified 1 July 2026
By the WhichVoIP editorial team
8 min read

~100 kbpsPer concurrent call on the safe G.711 codec

Under 150 msOne-way latency target for clear calls

Under 1%Packet loss ceiling before quality drops

+30%Headroom to add on top of raw call maths

The short answer

What internet speed do you need for a VoIP contact centre?

Budget about 100 kbps up and down per concurrent call on the G.711 codec, multiply by your peak simultaneous agents, then add roughly 30% headroom for signalling and other traffic. A 20-seat centre needs around 2.5 Mbps dedicated to voice alone, on top of everything else your network carries.

Per concurrent call, G.711, up and down

One-way latency target for clear voice

Packet loss ceiling before calls degrade

Headroom to add on top of the call maths

Agents Wearing Headsets On A Modern South African Contact Centre Floor — A contact centre is only as good as the connection under it: a link that handles ten agents at 09:00 can buckle when all fifty are live at peak.

The four numbers that decide call quality

Raw download speed is the least important figure. Voice quality is decided by four metrics, and only one of them is “speed”.

Bandwidth is how much data the link can carry. Latency is the delay a packet takes to arrive, and you want one-way latency under 150 ms. Jitter is the variation in that delay; high jitter makes voice choppy. Packet loss is data that never arrives, and above about 1% you hear it as robotic or dropped audio. A fast line with high jitter still delivers bad calls.

How much bandwidth one call actually uses

It depends on the codec, the compression method your platform uses to turn voice into data.

Codec	Quality	Bandwidth per call
G.711 (uncompressed)	High, PSTN quality	~100 kbps
G.729 (compressed)	Good	~30–40 kbps
Opus (dynamic)	Excellent, adaptive	~40–100 kbps

Plan on the safe side with G.711 at 100 kbps per call, both directions. Then scale by concurrency: it is your peak simultaneous calls that sets the requirement, not your total headcount.

Sizing the link for a contact centre

The traffic everyone forgets to count

Voice is never alone on the wire. The most common sizing mistake is budgeting for calls and ignoring everything else.

Your agents’ calls share the link with CRM lookups, cloud dashboards, file uploads, video meetings and often CCTV streams. If you size the connection for voice only, those workloads eat into call quality the moment the centre gets busy. Count total usage across departments, then give voice its own protected lane.

✓

Bottom line: isolate voice on its own VLAN and prioritise it with QoS, so a large CRM sync or a file upload can never starve a live customer call.

Fibre or wireless for a contact centre?

For a centre of any size, fibre should be the primary link and wireless the backup, not the other way around.

Requirement	Fibre	Fixed wireless
Consistency under load	Most stable at scale	Good, tower-dependent
10+ agents	Comfortable headroom	Workable, watch contention
Remote / no-fibre sites	Only where built	Reaches where cable can’t
Role in the design	Primary link	Ideal failover path

Wireless is a strong backup and the right primary choice in remote areas, but for a growing centre the reliability of fibre carries the core load, with wireless on standby for failover.

Optimising the network for voice

The right speed on paper still delivers bad calls without the right configuration underneath it.

Prioritise voice with QoSTag SIP and RTP traffic so it always wins a contention fight against data.

Isolate voice on a VLANKeep calls off the same broadcast domain as CRM, backups and CCTV.

Use business-grade routersConsumer boxes can’t prioritise voice or hold a stable session under load.

Wire the agentsCable the desks where you can; Wi-Fi adds jitter that voice feels first.

Test under real loadMeasure at peak with agents live, not on an idle speed test that flatters the line.

Watch out: a speed test at 08:00 tells you almost nothing. The number that matters is jitter and packet loss when every agent is on a call at the same time.

A contact centre doesn’t fail on download speed. It fails on jitter and packet loss at the busiest hour – the exact moment no speed test is watching.

WhichVoIP editorial view

Business Network Switch And Router Rack With Qos Configured For Voice Traffic — The configuration matters as much as the line: QoS to prioritise voice and a VLAN to isolate it turn raw bandwidth into consistent call quality.

Our verdict

Size a VoIP contact centre from peak concurrent calls, not headcount: 100 kbps per call on G.711, times your busiest simultaneous total, plus about 30% overhead, and then add the rest of your business traffic on top. Make fibre the primary link, keep wireless as failover, prioritise voice with QoS on a dedicated VLAN, and test at peak. Do that and the connection stops being the thing that limits your customer service.

Our recommendation: calculate voice bandwidth from peak concurrency, add 30% headroom plus your data load, run fibre as the primary with a wireless failover, and validate with a real peak-load test before go-live.

Sizing the connection for your contact centre?

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Frequently asked questions

How much internet speed does a VoIP contact centre need?

Budget about 100 kbps per concurrent call on the G.711 codec, both up and down. Multiply by your peak simultaneous calls and add roughly 30% overhead, then add your other business traffic on top.

How much bandwidth does one VoIP call use?

Around 100 kbps on the uncompressed G.711 codec, 30 to 40 kbps on the compressed G.729 codec, and 40 to 100 kbps on the adaptive Opus codec. Plan on G.711 to be safe.

How do I calculate bandwidth for 20 agents?

20 concurrent calls at 100 kbps is 2 Mbps for voice, plus about 30% overhead brings it to roughly 2.6 Mbps. Then add bandwidth for CRM, video and other traffic that shares the same link.

Should a contact centre use fibre or wireless?

Fibre should be the primary link for consistency at scale, with fixed wireless as a failover. Wireless is the right primary choice mainly in remote areas where fibre is not available.

What latency and packet loss are acceptable for VoIP?

Aim for one-way latency under 150 ms, low jitter, and packet loss under 1%. A fast line with high jitter still produces poor calls, so these matter more than raw speed.

Why do my calls drop even though my speed test looks fine?

Speed tests run on an idle line. Call problems usually appear at peak, when jitter and packet loss rise under load. Prioritise voice with QoS, isolate it on a VLAN, and test with agents live.

Keep reading

VoIP speed and network requirements
Call centre setup guide
Reduce call centre operational costs
Call centre buyer’s guide

Sources: ITU-T G.711 and G.729 codec references; Opus codec (IETF RFC 6716); ITU-T G.114 one-way latency guidance (under 150 ms); standard VoIP network engineering practice (QoS, VLAN isolation, peak-concurrency sizing). Verified 1 July 2026.