I am merely attempting to get a prerecorded mp3 voicemail greeting recorded into my actual voicemail account. This can't be uploaded--that would be way too simple. Patching a 1/8" to 1/8" cable from my laptop to my iPhone to play the mp3 while recording a voicemail greeting doesn't seem to work. When I try this, the iPhone mic stays active and records ambient sound. Any ideas? Thank you!