Awesome. You can do the same thing without this step:
3. Disable the phone's modem NAI by selecting MENU > # > 1 > 0 > 040793 > 9 > off > ok
on just about all non-EVDO phones. I didn't know there was a hack like this for the A900. The only reason I don't own one myself is because I thought it would cost me $49/mo extra if I wanted to continue to use my Sprint phone in my car like I do with my A700. A900 here I come
Edit: Sprint Tip: Dial *2 and say "credit for dropped call". That will give you $0.50 off your bill and you can do it 20 times a month. I have no problem doing this every month (and yes, I do drop at least that many calls when in the elevator at work).