I had one too.

With some of the later OSes I could reliably take calls. Namely the SHR-Project and QtMoko

However the device was still extremely limited in regard to resources. GPS could be utilized by an APP named TangoGPS, but there was no routing. You could import a pre-generated track and follow it. Using Navit for navigation was possible, but incredibly sluggish and tasked the device so much that phone calls could indeed be missed. Geocaching apps where available.

Also the handling was quite unpleasant with its strange shape and the deeply recessed screen.

All in all it was impressive what developers got out of this device and it was an interesting journey. But in 2010 when its screen cracked while I had it in my pocket with nothing else I was happy to stop fiddling with it an concentrate fully on my new N900.