Review on Yealink DD10K DECT Dongle Phones by Christine Pochmara

I bought this product based on two responses that said it would add DECT capabilities to my T54S desk phone. This information seems to be incorrect, when I insert the dongle into the phone's USB port I just get "unrecognized USB device". Looking at the release notes on Yealink website, it seems that this dongle needs v84 firmware to work on T4X phones and v85 firmware on T5X phones. There is no firmware v85 (yet?) for the T54S.