Call quality and troubleshooting
Why is call quality worse on Wi-Fi?
Wi-Fi is shared, half-duplex and prone to interference, so voice packets are delayed or lost when the airwaves are busy, when a device is far from the access point, or when it roams between access points. Voice cannot wait for retransmissions the way email or web pages can. Fixed desk phones belong on Ethernet; for laptops and cell phones, use 5 GHz, sit near the access point and reduce congestion.
What Wi-Fi does to a voice call
A voice call sends about fifty small packets per second in each direction and needs them to arrive at a steady pace. Wi-Fi delivers data in bursts, retries lost frames and pauses when a device switches access points. Each of those causes jitter or loss that a web page hides and a phone call reveals as choppy or robotic audio.
2.4 GHz is the busier band: it has only three non-overlapping channels, is used by neighbours' networks, and is shared with microwaves, Bluetooth and many smart devices. 5 GHz has more channels and less interference, but shorter range through walls.
Checks in order
- Move the device closer to the access point, or test right beside it. If quality improves, the problem is signal strength.
- Connect to the 5 GHz network rather than 2.4 GHz. Give the bands different names if your router merges them.
- Count what else is on the Wi-Fi: video streaming, cameras, guest devices. Move heavy users to Ethernet or a separate network.
- Disable SIP ALG on the router and enable QoS, including wireless QoS (WMM) on the access point.
- Check that the device does not roam mid-call between access points with weak overlap; poor mesh placement causes short dropouts.
- Restart the access point; consumer units degrade after long uptimes.
- If quality is still poor, run a call on Ethernet from the same spot. If it is clean, the issue is the Wi-Fi, not the service.
Design choices that avoid the problem
Desk phones and reception computers should be on Ethernet, ideally on PoE switch ports so they do not need power adapters. Staff who move around can use the mobile app on Wi-Fi with a business-grade access point and, if needed, a DECT cordless phone, which uses its own radio and is not affected by Wi-Fi congestion.
- Ethernet for anything that does not move.
- Business-grade access points sized for the number of devices, not one consumer router for the whole floor.
- A separate guest network so visitors' devices do not compete with staff.
- DECT cordless handsets for warehouse, clinic or shop floors.
A 3CTel specialist can review your floor plan and device list during planning and recommend which devices should be wired, wireless or DECT.
Related questions.
Is the mobile app better on Wi-Fi or cellular data?
It depends on which is better where you are. Strong 5 GHz Wi-Fi is excellent; weak Wi-Fi at the edge of range is usually worse than good cellular data. If calls are poor on office Wi-Fi, try turning Wi-Fi off on the phone as a test.
Will a mesh Wi-Fi system fix VoIP quality?
Mesh improves coverage, but each wireless hop adds latency and roaming between nodes can cause brief dropouts mid-call. Mesh with wired backhaul between nodes works well; wireless-only mesh is a compromise for voice.
Can I use Wi-Fi desk phones?
Some desk phones support Wi-Fi, and they work where cabling is impossible. They suffer the same limitations as any Wi-Fi device, so use them only where Ethernet is not an option and the access point is close and uncongested.
Last updated:
Not a 3CTel customer yet? See your recommended setup in four short steps.
Build My Phone System