As a Leasing Professional I would have loathed the 'whisper feature' because it takes me out of my game-face. I am all psyched up with my Mary Marketing face and voice and start my greeting when 'Whisper' kicks in. Aaaaarrrrgh! I've never liked it for that particular reason. But, from a tracking standpoint, I totally get it.
Now, if I were using all toll free tracking numbers, I might say 'forget it' altogether. But I have to say, I do know property management types who think it's a great feature.
Me....not so much. Not a 'Whisper' fan.