Peplink SD-WAN

http://<Your device’s IP>/cgi-bin/MANGA/support.cgi > makes sure “sip” is disabled
System>firmware>check and use most upto date firmware
Network>WAN> change mtu on WAN from 1440 to 1500
Network>WAN> check box “Independent from Backup WANs”
Network>QOS> – add application “all supported Voip Protocols” set priority to “High”
Misc.Settings>SIP> set to Compatibility mode and uncheck H.323