http://213.68.67.162/p2000w.htm
Running 'strings' on the firmware is really interesting.
One odd problem with the phone is that it only appears to support software updates from MS Windows Internet Explorer (IE for Mac, Mozilla, Firebird, Opera, Konquerer, and curl all fail). I was able to use netcat to update the firmware. If you don't have a windows machine handy for flashing, check this out:
http://nocat.net/~rob/zyxel/
If you hang the phone at 99% or before, you can apparently reboot the phone safely by taking the battery out. Once the phone starts checking the checksum of the new firmware, do not remove power!