1. Teams Only organization w/Phone System/Calling Plans
2. Polycom VVX VoIP phones (latest SfB online certified firmware)
When someone calls in, the Polycom phones and Teams apps that are logged into that account ring, but when we answer one of the Polycom phones, the person calling us cannot hear us. We can hear them. This happens about 3/4 of the time, but not always, and with seemingly no pattern. It doesn't seem to happen when answering using the actual Teams app - only when using the Polycom phones.
I've checked out our firewall settings and we are not blocking any of the documented ports or ranges of ports that need to be open, and there is nothing in the actual call log that indicates something is going wrong. I'm at a loss as to how to even begin troubleshooting this. Any advice as to where I can look for clues?