[ben1040]

Yep. I had no idea this was the case until I read an article that came out shortly after the original iPhone. The dialer app in iOS during those first few months was pretty buggy and had an occasional tendency to crash or lock up while on calls, especially when pressing the "hang up" button. Every time it locked up on me, it'd never impact a call in progress though (much to my annoyance when trying to hang up).

It made perfect sense once I read that the speaker and mic were wired straight to the baseband, and the state of the dialer application had zilch to do with what was going on in the baseband.