5 VoIP Problems I See Every Week (And How to Fix Them)
I manage VoIP systems for over 40 clients, and I see the same handful of issues pop up constantly. The good news? Most of them are easy to fix once you know what’s going on. Here are the five biggest offenders.
1. Choppy or Robotic Audio
This is the number one complaint I hear. Someone calls in and it sounds like they’re talking through a fan. Nine times out of ten, this is a network issue — not a phone issue. Your VoIP traffic is competing with everything else on your network: file downloads, streaming, Windows updates.
The fix: set up QoS (Quality of Service) on your router to prioritize voice traffic. If your router doesn’t support QoS, it might be time for an upgrade. A dedicated VLAN for your phones also works wonders.
2. One-Way Audio
You can hear the caller, but they can’t hear you (or vice versa). This is almost always a NAT or firewall issue. Your router is blocking the audio stream in one direction because it doesn’t know how to handle the SIP traffic properly.
The fix: make sure SIP ALG is disabled on your router (seriously, SIP ALG causes more problems than it solves), and check that your firewall rules allow the RTP port range your system uses.
3. Calls Dropping After 30 Seconds
If calls connect fine but then drop at almost exactly the 30-second mark, that’s a registration timeout issue. Your PBX and your SIP provider aren’t keeping the connection alive properly.
The fix: adjust your registration expiry and keep-alive settings. I usually set registration to 120 seconds and enable a keep-alive ping every 25 seconds. This keeps the NAT mapping active.
4. Echo on Calls
Echo is annoying and makes you sound unprofessional. It’s usually caused by either a bad handset, a headset with poor echo cancellation, or an impedance mismatch on an analog line if you’re using an ATA adapter.
The fix: test with a different handset or headset first. If the echo persists, check your jitter buffer settings and consider enabling echo cancellation in your PBX software.
5. Phones Not Registering
You come in Monday morning and none of the phones are working. They’re showing “No Service” or just sitting there doing nothing. This usually means your PBX server rebooted, your internet dropped overnight, or your DHCP handed out a new IP to the server.
The fix: set a static IP for your PBX server (always), set up monitoring so you know when it goes down, and configure your phones to auto-provision so they re-register on their own after an outage.
The Bottom Line
VoIP is fantastic technology, but it does require some care and feeding. If you’re dealing with any of these issues and can’t figure them out, reach out. This is literally what I do all day, and I’m happy to help.
Got questions? Reach out at jeremy@lizzotte.com or use my contact form.
— Jeremy Lizzotte