Does anyone know if checking your voicemail uses up your airtime minutes (like it used to on my Treo 650 with Sprint?) I don't know where the actual voice messages are stored, is it on the iPhone itself or on the AT&T network.
I can't say for certain, but i don't think it does. First off, there's a little slider bar when listening to the voicemail, allowing you to rewind or fast forward - that would be somewhat laggy if done while dialing in. Second, i just gave it a try with a 2 minute long voicemail and my usage (according to the numbers on the iPhone) didn't change.