Common VoIP Problems and How to Fix Them

VoIP is supposed to save money and add features. But when calls sound terrible or drop randomly, it's worse than the old phone system ever was.

Problem 1: Choppy or Robotic Audio

Problem 2: One-Way Audio

You can hear them, but they can't hear you (or vice versa).

Common fix: Disable SIP ALG on your router/firewall—this fixes it about 50% of the time.

Problem 3: Dropped Calls

Calls disconnect randomly, usually after a specific duration. This is often a timeout or connection issue.

• Increase SIP/UDP session timeouts on your firewall to prevent premature connection termination
• Check for internet micro-outages or packet loss that might be causing disconnections
• Ensure phones are re-registering before timeout—check registration intervals in phone system settings
• Review NAT traversal settings—some firewalls drop long-lived connections incorrectly

Problem 4: Echo

Your own voice coming back to you with a delay. This is usually an acoustic feedback issue.

• Use quality headsets instead of speakerphones to eliminate acoustic feedback loops
• Lower the speaker volume on affected devices—high volume increases echo likelihood
• Enable echo cancellation on phones that support it—most modern IP phones have this feature
• Check for network latency—high latency can make echo more noticeable and disruptive

Problem 5: Delayed Audio

Noticeable delay leads to people talking over each other.

The QoS Primer

Quality of Service (QoS) is often the missing piece. Without QoS, your network treats a VoIP packet the same as a Windows update download.

Quick Diagnostic Steps

Follow this systematic approach to isolate VoIP problems:

1. Test with wired connection: Eliminate WiFi as a variable. If problems disappear, the issue is wireless-related.
2. Check one call at a time: Is the problem consistent or intermittent? Does it affect all calls or specific ones?
3. Test internal calls: Are calls within your network affected? If only external calls have issues, it's likely internet or firewall-related.
4. Check other network services: Is everything slow, or just voice? This helps determine if it's a general network problem.
5. Look at timing patterns: Correlate problems with business hours, scheduled backups, or peak usage times.
6. Review recent changes: Did someone change firewall rules, update firmware, or modify network settings recently?
7. Check phone system logs: Review call logs and system diagnostics for error messages or patterns.