I agree with all your all your points, especially about collecting so many rollover minutes, and with mobile-to-mobile, we have the equivalent of a monster family plan at the cheapest monthly rate. One thing: VOIP quality is *better* than traditional landline, when it's good. At least our dedicated VOIP service separate from our broadband provider is better, when it's spot-on; problem is, it's highly sensitive to network conditions, both local and of the broadband provider's. Especially anything that uses the upstream data. If I do a large backup to my .mac account or publish a lot of photos to a .mac gallery, I can hear the other party clear as a bell, better than traditional landline, but my speech breaks up terribly for them. We have a 450 kbps upstream cap, that usually sits at around 400 kbps: that should be plenty for .mac uploads that tend to stall at around 50 kbps plus the voice upstream, which as stated by the provider only requires about 200 kbps or so upstream at the very most. But I guess the streams walk all over each other. While the data seems steady, the photos get up to .mac gallery as fast as if I wasn't using the phone, the outgoing voice is terrible during these time. Other network conditions than sometimes affect outgoing and incoming voice quality. Internal-only network use, like streaming movie from our Macs to the Apple TV over 802.11g or even mixed mode b to g, don't affect it at all; but the VOIP box is wire-connect to the router. Succinctly, it's better at its best but unstable and unpredictable. (We chose to use it because the former owner of our townhouse, in an apparent attempt to wire the landline phone system to every room, destroyed all the copper in the house, didn't declare such and it's hard to tell a line is bad on a line with no service when inspecting a house; it's a much better deal than paying the estimated $2,000 to have the house rewired, and the monthly service fee is half what we'd pay the local landline provider for fewer features.)
I assume this has to be a hacked native iPhone application, not an Apple-compliant Web application. If/when Apple and AT&T offer such a service, officially, I would certainly be interested, even if there were a small fee -- reasonably, US$5 - US$10 a month -- as it would use my usual cell number, calls would just make it in without forwarding and such, I'd be able to use Visual Voicemail, and unanswered calls would go to my AT&T voicemail. Until then it's interesting, but not useful to me.
While cool, it's not that exciting for a few reasons.
1) Current cell plans give plenty of minutes (my wife and I never use all of our minutes. I think we have over 2000 on rollover).
2) VOIP only works while in a WiFi area.
3) Not feasible for use in cities while walking around town or in the car.
So, while it's great while you're in your house, etc. This is NOT going to replace your cell phone.
However, if would be nice to use your iPhone as a cell phone while abroad and as your "landline" while at home. Too bad VOIP quality pales in comparison to good old copper ... at least that's what I hear from people who have had it.
