Most call problems in an office come from the network, not the phones. A setting on your router, firewall or Wi-Fi can cause one-way audio, calls that drop at 15 or 30 minutes, phones that go offline, choppy audio, or calls that don't ring.
These guides are written for business owners and office managers, with enough detail for the IT person you forward them to. Each one explains what goes wrong, why, how to fix it, and how to tell it worked.
Start here: run the free Net Checker on the office network. It checks your connection to Cannon VoIP and flags common router problems. Then check the guides below, starting with SIP ALG and UDP timeouts, which cause most problems.
Turn Off SIP ALG
SIP ALG is a router feature that rewrites phone call traffic and often breaks it. How to turn it off, and how to tell it worked.
Set UDP Timeouts to at Least 300 Seconds
If your router forgets about phone traffic too quickly, calls stop ringing and audio cuts out. How to set the UDP timeout to 300 seconds or more.
Allow Cannon VoIP Through Your Firewall
The server names and ports your firewall needs to allow so Cannon VoIP desk phones, apps and video meetings work.
Fix Double NAT (Two Routers in a Row)
Two routers in a row can cause one-way audio and phones that stop ringing. How to spot double NAT and fix it.
Prioritize Voice Traffic with QoS
QoS tells your router to send call audio ahead of downloads and streaming. How to set it up for Cannon VoIP desk phones and apps.
Fix Bufferbloat with Smart Queue Management
Bufferbloat makes calls lag and break up when the internet is busy, even on fast plans. How to fix it with smart queue management (SQM).
Stop Wi-Fi Band Steering and Roaming from Dropping Calls
Wi-Fi features that move devices between bands or access points can drop calls on cordless handsets and phones running the app. How to fix it.
Guest and Isolated Wi-Fi Blocking the App
Guest Wi-Fi and client isolation can stop the Cannon VoIP app and Wi-Fi phones from working. How to tell, and what to change.
DNS and Content Filtering Blocking Cannon VoIP
Web and DNS filters can block the servers Cannon VoIP phones and apps need. How to allow them.
VPNs and Security Software Interfering with Calls
VPNs, antivirus and endpoint security can slow down or block calls in the Cannon VoIP app. How to set them up so calls work.
Mesh Wi-Fi Systems and Calls Cutting Out
Home-style mesh Wi-Fi can cut out calls in an office. Why it happens, the settings that help, and when to upgrade.
Wi-Fi Power Saving Causing Missed Calls
Power saving on Wi-Fi access points and devices can make calls ring late or not at all. How to turn it off for phones.
Mobile Hotspots and Carrier-Grade NAT
Cellular hotspots and some fixed wireless or satellite internet use carrier-grade NAT, which can cause one-way audio and missed calls. What to know.
For background on what makes calls sound good or bad, see What makes VoIP call quality good or bad and One-way audio.
Still having trouble? Contact Cannon VoIP support at 888-973-0515 or support@cannonvoip.com.