I had the call announcement on my Nokia N95 8G. Loved the phone.......until I got a hold of my first BB. Some features i miss, but its nice to be able to access email and everything else offered by BB.
Option 2 is to go to AT&T Labs text-to-speech demo site. ther you can type in whatever you want it to say, choose voices and effects, adn download the sound file to your BB for use as a ringtone, etc. I have a few ringtones and notifications recorded this way.