In order for 3CX to work with VoIP providers and directly connected external extensions it must be able to establish communication to the devices and VoIP provider. Additionally, the firewall must be prepared to operate correctly with SIP. A firewall without an integrated SIP server (such AVM Fritz box or Speedport) or SIP ALG is preferable.
How to resolve common VoIP issues.
- Yes -if you intend on using remote extensions using the 3CX Tunnel Protocol (within the 3CX clients for Windows / Android / iOS) or when using the 3CX Session Border Controller. 3CX Media Server (RTP) – WAN audio/video/t38 streams. Yes – if you intend on using remote extensions, WebRTC or a VoIP Provider.
- UDP time-out value causes VoIP calls to drop or have poor quality. What to do if VoIP calls drop or have poor quality. VoIP call issues over site-to-site VPN or with IPS configured. Resolve issues with VoIP call quality when there is a site-to-site VPN or IPS configured on XG Firewall.
The most common issues encountered with VoIP are poor call quality, one way audio, or calls dropping.
You only need to carry out the steps that are relevant to your own VoIP setup.
UDP time-out value causes VoIP calls to drop or have poor quality
What to do if VoIP calls drop or have poor quality.
Condition
VoIP calls drop or have poor quality.
Cause
If there are no errors in the SIP configuration, VoIP issues are usually due to the UDP time-out value.
XG Firewall has a default UDP time-out of 60 seconds which is usually low for reliable VoIP communication. Usually the VoIP provider recommends a UDP time-out value, typically 150 seconds.
To change the current UDP time-out value from the command line interface (CLI), choose option 4. Device Console and do as follows:
Remedy
- Type: show advanced-firewall
The current UDP time-out value is shown next to UDP Timeout Stream.
- Type: set advanced-firewall udp-timeout-stream 150
The above command will increase the UDP time-out to 150 seconds. If your provider recommends a different value, use that.
What to do if VoIP calls drop or have poor quality.
Condition
VoIP calls drop or have poor quality.
Cause
If there are no errors in the SIP configuration, VoIP issues are usually due to the UDP time-out value.
XG Firewall has a default UDP time-out of 60 seconds which is usually low for reliable VoIP communication. Usually the VoIP provider recommends a UDP time-out value, typically 150 seconds.
To change the current UDP time-out value from the command line interface (CLI), choose option 4. Device Console and do as follows:
Remedy
3cx Behind Sophos Xg
- Type: show advanced-firewall
The current UDP time-out value is shown next to UDP Timeout Stream.
- Type: set advanced-firewall udp-timeout-stream 150
The above command will increase the UDP time-out to 150 seconds. If your provider recommends a different value, use that.