Update (14/01/2020): the latest build of 8.0.3 appears to resolve this issue and you no longer need the port defined in the SIP profile as described in the comments.
I am currently deploying a new Ribbon SBC Edge running that latest firmware 8.0.3. We where having issues with calls failing to establish media – the calls rang and you could answer them, however nothing could be heard either side. Upon investigation we found that the firewall was blocking port 5061 inbound from Microsoft Teams, even though this specific trunk was configured to use port 5063. Opening port 5061 resolved the issue, however it didn’t explain why this was happening. Looking at the Ribbon SIP ladders I could now see that calls were being initiated on port 5063, but then switched to 5061 mid-call.
I checked with a friend at Microsoft who confirmed that this shouldn’t happen and was able to replicate it in their lab. They also noticed that the contact header didn’t include the port. To confirm this issue was Ribbon software related I rolled back to build 8.0.2, and sure enough the port that was missing in the contact header had returned.
Here you can see the difference:
I am currently working with Ribbon on this issue. For now I suggest you hold off any planned upgrades. I will report back on this post once Ribbon have confirmed.