Hello,
I hope you are doing great,
Would you mind giving us the logs from your polycom devices, as per my experience polycom have some control messages that do not behave like the way the RFC describe it.
Most of the time when you have problems like this they are caused because the ALG it is not able to allocate the correct ports or modify the information on the payload as required.
Always keep in mind that you have a couple of ways to fix this.
Please go to your polycom device web page, in there if you go to admin configuration then to network and then to network IP.
In the bottom you will find a part that says Security server:
In here you can fix the problem in a couple of different ways.
You can use fixed ports for the RTP streams, which means that you can only allow those ports and create static translations (As per my points of view this will be one of the best things you can do).
Then you will have the option to enable Firewall traversal h.460 but you need first to confirm if the SSG support this, to be honest I don't think they do, since I review the ALG features and I have not found anything about that, probably I will avoid to use this one.
Then you have nat configuration, you will have deactivate-auto-manual, ill rather use it manual and put the public IP address that you have in there.
Then there is the last option that says its nat compatible with H.323, I don't think you should mark this.
As you know h.323 its an umbrella protocol, so it is not required that the device support all the sub features.
My recommendation will be:
1. Use static ports.
2. Use manual nat
3. Create static nat translations (With other networking vendor I have seen that if you are matching the nat based on ports it will not handle properly the ALG).
Also you can provide the logs on the Polycom device and I can try to tell you what happened.
To retrieve this information you can follow this procedure:
You can go to Diagnostics - System registry - Download Files, and download everything.
I hope this information will be helpful, and if you need anything else please let me know.
Regards,
Luis Sandi