Bandwidth
A single VoIP call uses about 100 kbps in each direction. Ten calls at once need about 1 Mbps up and down. Almost any business internet has enough. The real issue is quality, not speed.
| Measure | Good for VoIP | Trouble |
|---|---|---|
| Latency (ping) | Under 100 ms | Over 150 ms |
| Jitter | Under 30 ms | Over 50 ms |
| Packet loss | Under 1% | Over 2% |
| Upload speed | 1 Mbps per 10 calls, spare | Saturated by backups or uploads |
The checklist
- Business-grade internet. Fibre is ideal; cable is fine with good upload.
- A router that supports quality of service (QoS), so voice goes first.
- SIP ALG turned off on the router; it breaks calls more often than it helps.
- A separate voice VLAN on a managed PoE switch.
- Cat5e or Cat6 cabling to every desk phone.
- A UPS (battery backup) on the router and switch.
- A backup internet line, or failover to mobile apps, for critical lines.
Symptoms and causes
- Choppy or robotic audio: jitter or packet loss, often a busy upload.
- One-way audio: usually a router or firewall setting (SIP ALG or NAT).
- Calls drop after 15 or 30 minutes: a router session timer.
As part of the VancouverCabling.ca group, we check this during every install. See installation and cabling.
Quick answers
How much bandwidth does one VoIP call use?
About 100 kbps up and down per call with the common G.711 codec, less with compressed codecs.
Can VoIP work over Wi-Fi?
Yes for apps and Wi-Fi phones, if the Wi-Fi is solid. For desk phones, a wired connection is best.