Teams on Mac keeps disconnecting during the calls

Dear community, 

I am looking for your wisdom and kind help with really annoying issue with Teams calls on Mac. 

MacOS Catalina 10.15.5, Teams version is the latest 1.3.00.9271. Two machines has the same versions. 

When one user initiates the call to another - call gets disconnected after 5-10 seconds. No matter who calls whom - the result is always the same. 

What we did so far:

- Reinstalled MacOS and Teams

- Disabled ESET completely 

- Disabled MS ATP

- Read a lot of info on the Internet, but nothing works... 

Would be really appreciated if anyone can point us to the right direction...