Not only does the F3000 look like it could replace your existing mobile, but SIP support means roaming between different access points and SSID is a very real possibility. The upshot of this means that while being a long way from a true dual-chipset device, it does enable an element of roaming without dropping calls, and best of all, it requires no PC link.
It's also a very straightforward set-up, which scans for the nearest signal and is as easy to link to WEP and WPA connections as any open network. SIP functionality takes it a step further than the other phones here, enabling SMS-like messaging to both other SIP-enabled devices and GSM handsets.
The closest thing to true mobile non-Skype VoIP, and as easy to use and acceptable to look at as any GSM mobile. Tom Dennis