FreeSBC dropping all responses from IP Phone

[hardwiired]

Hey!

I'm kind of having a weird issue and I am not sure where else to turn at this point. I want to get this sorted before I go full production and purchase ProSBC.

I followed the "Remote Worker" and "Hosted PBX" FreeSBC setup guides and I can make outbound calls fine. However, when I receive an incoming call the SBC keeps sending invites and will not acknowledge and pass the IP Phone's 180 ringing response.

Here is my topology for an incoming call:

Asterisk PBX -> FreeSBC -> IP Phone
I should note the IP Phone is registering through the SBC to the Asterisk PBX.

I did a packet capture on the FreeSBC box and the SBC is indeed seeing my 180 ringing response but for some reason it is not passing it to Asterisk. In fact, it is not even showing any response on the "Call Trace" GUI. The only indication that the SBC is getting a response from my IP phone is via a pcap on the SBC.
I have tried this from multiple IPs and phones. Same behavior.

To make things weirder, every once in a while incoming calls will work fine but its a one off occurrence. No config or topology changes, just randomly will work.

Does anyone have any insight?

[Admin]

Hi

Please check the contact header sent by Asterisk. The contact header must be the same as when ProSBC forwards registration messages. You can check ACL table to see if the packet is dropped and the reason for the drop.

[hardwiired]

Hey!

Thank you so much for getting back to me!

I will go ahead and check that and let you know what I come up with.