Bandwidth per call, by codec
| Codec | Payload | On the wire (Ethernet, 20 ms) | Typical use |
|---|---|---|---|
| G.711 (PCMU/PCMA) | 64 kbps | 87.2 kbps each way | Default for most business VoIP and SIP trunks |
| G.722 | 64 kbps | 87.2 kbps each way | HD (wideband) voice between desk phones |
| G.729 | 8 kbps | 31.2 kbps each way | Low-bandwidth links |
| Opus | 6–510 kbps (variable) | Depends on bitrate | Softphones, WebRTC, apps |
Work out your own numbers with the VoIP bandwidth calculator.
Why upload matters
Every call sends as much as it receives. Many cable plans have upload speeds a small fraction of download speed, so a busy office runs out of upload long before download — especially during cloud backups or video meetings. When upload is full, voice packets wait in line; see the bufferbloat test.
About this speed test
It runs four parallel streams to Cloudflare's speed test servers for 9 seconds each way and discards the first 1.5 seconds of ramp-up. Results can differ from your provider's test because of server location, Wi-Fi, the device, and browser limits. On gigabit connections, browser tests often read low.
Frequently asked questions
How much internet speed do I need for VoIP?
About 100 kbps per simultaneous call in each direction with the G.711 codec, which most business systems use. Ten simultaneous calls need roughly 1 Mbps up and 1 Mbps down, plus whatever the office uses for data at the same time.
Does upload speed affect VoIP calls?
Yes. Each call sends your voice upstream at the same rate it receives the other person's voice. If upload is saturated by backups, file transfers or video, outgoing voice is delayed or dropped, and the other party hears you break up.
Is 10 Mbps enough for VoIP?
For voice alone, 10 Mbps upload and download is enough for dozens of simultaneous G.711 calls. In practice the same connection also carries computers, video meetings and backups, so what matters is whether the line stays uncongested — QoS or a dedicated voice connection keeps calls clear.
Why is my speed test different from my ISP's?
Different test servers, distance, time of day, Wi-Fi versus wired, the device's own speed, and browser overhead all change results. Compare tests from the same tool, on a wired computer, at the same time of day.
Does faster internet improve call quality?
Only up to a point. Once you have enough bandwidth for your calls plus data, a faster plan won't fix jitter, packet loss or poor Wi-Fi. A steadier connection or better queue management usually helps more than a faster one.
How many calls can a 1 Mbps upload handle?
About 11 G.711 calls on paper (1,000 ÷ 87.2), or about 8 if you keep 25% headroom. With G.729 the same 1 Mbps carries roughly 24 calls with headroom.
Sources & references
- IETF RFC 3550 — RTP: A Transport Protocol for Real-Time Applications
- IETF RFC 6716 — Opus audio codec
- Cloudflare speed test (endpoint used by these tools)
Written by Eric · Reviewed November 2026