I too picked up this phone!
I have this device, it runs ICS 4.0.4, feels quite old.
I wanted to updated this to Jelly Bean at least, many popular apps are not available in the store, or simply do not work with it.
No 'Talking Caller ID' app works with it currently, all of them say 'Call from Unknown'.
I'm willing to compile Cyanogenmod from source if necessary (if and when I learn how to do it), but I'd like to create an existing image backup for my device first. Also, I'll need to ensure that the Landline App and DECT 6.0 features from Panasonic would work on my new rom.
Any tips anyone? Or am I looking at the impossible?