Set UDP Timeouts to at Least 300 Seconds

Who this is for: Desk phones and adapters, and the apps on office Wi-Fi.

What goes wrong

• Phones stop ringing for incoming calls a few minutes after the last call, then work again after you make an outgoing call.
• Audio goes silent in one direction after a long pause, a long hold, or a muted stretch of a call.
• Calls drop after a set amount of time, often the same length every time.

Why it happens

Call setup and call audio travel as UDP traffic. UDP is a fast way to send data that doesn't keep a constant connection open.

Your router keeps a short memory of each UDP conversation so it knows where to send the replies. If that memory (the timeout) is too short, the router forgets the phone, and calls or audio coming back from Cannon VoIP have nowhere to go.

How to fix it

1. Sign in to your router or firewall's admin page.
2. Find the setting for UDP timeout, UDP session timeout, or connection timeouts.
3. Set it to at least 300 seconds (5 minutes). If the router has separate timeouts for SIP or for call audio, set those to at least 300 seconds too.
4. Save, then restart the router.
5. Unplug each desk phone for 10 seconds and plug it back in.

Notes for common router types

• On most home and small office routers, this setting is under Advanced > NAT, Firewall or Connection Settings. Some don't offer it at all. If yours doesn't, a business-grade router is worth it for an office that relies on its phones.
• On most business firewalls, look under Firewall > Advanced, System > Advanced, or the session or connection settings. Some firewalls set timeouts per rule or per service. Set it on the rules that allow phone traffic.
• Don't set the timeout extremely high (hours). That can use up the router's memory on a busy network. 300 to 600 seconds is the usual sweet spot.

How to tell it worked

• Leave the office phones idle for 15 minutes, then call in from a cell phone. Every phone that should ring, rings.
• Put a call on hold for 5 minutes, then take it off hold. Both sides still hear each other.
• Run the free Net Checker to confirm your connection to Cannon VoIP.

More router settings that affect call quality

• Turn Off SIP ALG
• Allow Cannon VoIP Through Your Firewall
• Fix Double NAT (Two Routers in a Row)
• Prioritize Voice Traffic with QoS
• Fix Bufferbloat with Smart Queue Management
• Stop Wi-Fi Band Steering and Roaming from Dropping Calls
• Guest and Isolated Wi-Fi Blocking the App
• DNS and Content Filtering Blocking Cannon VoIP
• VPNs and Security Software Interfering with Calls
• Mesh Wi-Fi Systems and Calls Cutting Out
• Wi-Fi Power Saving Causing Missed Calls
• Mobile Hotspots and Carrier-Grade NAT

See all router settings · What makes call quality good or bad