To be honest have only tried it a few times,
First time i tried it was with a female friend, i could hear the Rabbit she had going in and out, i was tryin so hard not to laugh it kinda put me off, she came but i had to fake an orgasm in the end she still to this day doesn't know.
Second times (plural) or so my then girlfriend used to get so turned on by my voice she would orgasm in about thirty seconds, which i was glad of when she'd ring at 3 in the mornin. Then i could roll over and go to sleep.
The last time i tried it i dropped the phone and broke it.
God help me if i get a cam !!!!!