I get called into offices where VoIP call quality is terrible. Choppy audio, dropped calls, one-way audio. Nine times out of ten, the problem is not the VoIP provider. It is the WiFi.
WiFi vs Ethernet for Voice: The Numbers
| Metric | Ethernet | WiFi 5 (802.11ac) | WiFi 6 (802.11ax) |
|---|---|---|---|
| Latency | 1-2ms | 5-30ms | 3-15ms |
| Jitter | < 1ms | 5-50ms | 3-20ms |
| Packet loss | ~0% | 0.5-3% | 0.1-1% |
| Bandwidth consistency | 99%+ | 60-80% | 80-95% |
Voice quality degrades noticeably above 30ms jitter and 1% packet loss. WiFi frequently exceeds both thresholds.
The Real Problem: Channel Congestion
Your office probably has 30-50 devices on WiFi: laptops, phones, tablets, IoT devices, smart TVs in conference rooms. All of them compete for airtime on the same channels.
When two devices transmit simultaneously, both packets are destroyed. Both devices wait a random interval and retry. During peak hours with 50 devices, this collision overhead can consume 30-40% of available airtime.
Voice packets are small (100-200 bytes) and sent every 20ms. They cannot tolerate the random delays caused by WiFi contention. A web page does not care about 200ms of extra latency. A voice call absolutely does.
The Fix
For desk phones: Always use Ethernet. No exceptions. Run a cable. Use a PoE switch so phones get power and data from one cable.
For softphones on laptops:
- Use 5 GHz band exclusively for voice (less congestion than 2.4 GHz)
- Enable WMM (WiFi Multimedia) QoS — prioritizes voice packets
- Deploy access points at 1 per 15-20 users (not 1 per floor)
- Separate SSIDs for voice and data traffic
For conference rooms: Hardwire the conference phone. USB speakerphones with a wired laptop connection work far better than Bluetooth or WiFi-connected conference devices.
AP Placement Math
| Room Size | Users | APs Needed | Recommended Model |
|---|---|---|---|
| Open office < 2000 sqft | 10-20 | 1-2 | WiFi 6 enterprise |
| Open office 2000-5000 sqft | 20-50 | 2-4 | WiFi 6 enterprise |
| Multi-floor office | 50-100 | 4-8 | WiFi 6E enterprise |
| Warehouse/campus | 100+ | 8+ | Outdoor + indoor mix |
Rule of thumb: if more than 15 devices associate to one AP, voice quality will suffer during peak hours.
VestaCall (https://vestacall.com) is one provider that gets this right provides a free network readiness assessment before deployment. They will identify WiFi dead spots and congestion issues before you port a single number.
