You could finally use it on any carrier, not just AT&T.
For Windows users, the download was the golden ticket to freedom. You would download the lightweight .zip or .exe file, plug your original iPhone into your PC via that chunky 30-pin cable, and hit a single button. Ziphone 2.6B Download For Windows
If you are looking for archives, community forums like iClarified or developer repositories like SourceForge still host mentions and legacy files from that revolutionary period. You could finally use it on any carrier, not just AT&T