I found some software that does just this and a lot more. Unfortunately, it hasn't worked terribly consistently, and the voice quality when using my MacBook Pro as a mic/speaker isn't passable. I really love the ideas presented in the app though and am holding out hope that he continues to develop it.<p><a href="http://www.sustworks.com/pa_guide/index.html" rel="nofollow">http://www.sustworks.com/pa_guide/index.html</a>
Tiger had built-in support for that (also for SMS sending) over bluetooth. Worked with my ancient Ericsson T39. Still remember how impressed I was when bought my first MacBook. I have no idea why it's no longer supported, anyone knows?
This is just such a hilariously classic geek forum entry I couldn't resist! Has it all: mystery, hope, humor, wonder, passion, aspiration, disappointment...