Hamilton Group · Free Tool

VoIP & Teams Call Capacity Checker

Work out how many simultaneous calls your connection can actually carry, where the ceiling is, and whether upload — almost always the real bottleneck — is about to become your problem.

Enter your connection speeds to begin
more audio calls
more video calls
Upload
Download

1. Your connection

Use the speeds you actually get, not the ones you were sold. Run a speed test from the office during working hours.

The number that matters most.
Never plan to fill a line. Bursts need somewhere to go.

2. Calls at your busiest moment

Not your total headcount — how many are on a call at the same time, on your worst Monday morning.

Type of callPer callHow many

3. Everything else using the line

Calls do not have the connection to themselves. This is where most capacity problems actually come from.

Quality controls in place
QoS configuredVoice prioritised on the router and switches
Separate voice VLANHandsets isolated from general traffic
Backup internet connectionFailover if the main line drops
Wi-Fi is used for callsRather than wired handsets or docked laptops

What this tells you

What "good" looks like

Bandwidth is only half of it. A fast line with high jitter still sounds terrible, and this is the part a speed test will not show you.

MeasureTargetWhat happens past it
Latency (one way)under 100 msPeople start talking over each other
Jitterunder 30 msRobotic or choppy audio
Packet lossunder 1%Words and syllables drop out
Upload headroom20% spareQuality collapses under bursts, not averages

Calls breaking up and nobody can say why?

Hamilton Group measures what is actually happening on your line — jitter, loss and contention over time, not a one-off speed test — then fixes the cause. Book a free network review.

An estimate based on typical bandwidth per call, including protocol overhead. Real usage varies with codec, resolution, how many people are in a meeting and what each client negotiates — Teams in particular adapts quality to the connection it finds, so it degrades rather than fails. Bandwidth is necessary but not sufficient: latency, jitter, packet loss, Wi-Fi quality and how your router handles congestion decide call quality just as much. Use this to size a line, then measure the real thing.