Balance20 intermittent one way audio

Started using the Balance 20 about 2 months ago. We have been having intermittent one way audio. The caller on the WAN side can hear the agent on the LAN. The Agent on the LAN can’t hear the Caller on the WAN side. The caller can calls back and both parties can hear each other. I do have a NAT Mapping rule, WAN to LAN.
Any thoughts?

Dear Robbie,

I hope you are doing well. I will continue to work with you on the ticket you have opened.

Kindly,

Soriam

This is likely a port forwarding and/or firewall problem. Do you have a VoIP server on your LAN, or are you using a cloud server?

Coming from WAN1 PF port rules 5060 ~ 5080 UDP & 10000~20000 UDP to Adtran 192.168.1.248 . Out of Adtran to PRI on PBX. I believe these are right. 90% calls are successful. Using Level3 for carrier. I have no firewall rules in the Peplink at this time.

You probably have an issue with our outbound rule. It may be using the intended WAN 90% of the time but not always. Should be something like:

source = LAN address of PBX
port = any
destination = any
algorithm = enforced

With enforced the PBX will have no outbound access if that WAN is down. You may later want to change it to Priority but you use Priority then you must also check the box for Terminate Sessions on link recovery. For now while you test I recommend Enforced.

Be careful as there are some rules “under the covers” that will take priority over the rules you define. I don’t know if your gear is using similar ports, but this post has some good information when Nat-T and SIP is involved.