Troubleshooting Steps
1. The first step is to check the call history. Try your best to get a detailed call example from
the customer. Check the MoS scores in the portal. NOTE: Even if the scores are green or
show 4.5, still hover over the MoS score. There could still be packet loss.
2. If you see packet loss on calls from the customers side of the call, you can start with having
them reboot their router/modem. If the packet loss continues you can have them call the
ISP. Also recommend that the ISP disable SIP alg and the firewall on the modem/router.
3. If the ISP checks out then the router would be the next step. Make sure SIP ALG is disabled
and follow the guides below. QoS is also a very important VoIP setting on firewalls. QoS
allocates a set amount of bandwidth for VoIP traffic. If this is not enabled there can be call
quality issues during peak times.
Generic firewall rules:
https://support.viirtue.com/hc/en-us/articles/360001134923-Firewall-settings-generic-
Sonicwall Guide:
https://support.viirtue.com/hc/en-us/articles/115005161686-Configuring-your-Sonicwal
l-for-Viirtue
Peplink Guide:
https://support.viirtue.com/hc/en-us/articles/360024302632-How-to-program-a-Peplink
-with-Viirtue-VoIP-settings
4. If these changes do not work, you can change the transport type of the phones from UDP
to TCP. While this still indicates a network issue, the phones can work well running TCP.
This can be done through the NDP Server. Click the device model to change the transport
type.
5. If there is still call quality issues you will need to generate PCAPs from the local network.
The pcap will be able to isolate exactly where the packets are being dropped and why.