...
This guide assumes you have the charging cradle that allows you to update the firmware directly with the Handset Administration Tool (HAT). The HAT is available here: http://support.polycom.com/PolycomService/support/emea/support/voice/wi-fi/spectralink_8020_wireless.html
The current version is "SIP Handset Administration Tool (HAT) Software - WTB1xx and WTE 1xx (2.8.21.0)"
Power off your 8020 and put it int he cradle. The HAT porgram should then connect to the phone. Choose the firmware tab. Brows to each individual bin file, and select 'Update'.