Generally speaking; this issue is due some failure in the system heuristics that tell it "The speaker device and microphone device are NOT properly calibrated and synced up together".
The best way to avoid this issue is to use one of our Lifesize Generation 2 Phones -- where the mic and speaker are a single device.
Other than that, to troubleshoot: there's a PING DELAY TEST tool you can run from the Icon 600's web interface:
Log into web interface using the following credentials:
There will be a new "support" tab
From there you'll access the 'audio' sub-tab.
From there you'll hit 'run ping delay test'
There should be some pinging and blips. -- run it a few times if it's failing
If it still continues to fail; we'll need to evaluate your environment further.
I highly recommend our new LiveChat feature~!