Using a web browser I logged into the admin site for the DECT base and, went to the “Miscellaneous” option on the menu and selected “Update Firmware.” The device reported that it would download the new firmware and restart, which might take a few minutes. About 3 minutes later it was rebooted and again available on the network. Revisiting the admin interface the system status now shows as follows:
The handsets seem to be working normally. I guess I’ll find out more as I go about using them over the next few days.