Maybe someone already has.
If you want to call some one who has an answering machine, 2 voice mail accounts, a secretary, three phone lines, two email accounts and SMS messaging, there should be a single entry point to get through to the person if they are at the end of any one of these connection points. The caller would call one number, then the application would begin calling all three phones until it got a live person and would patch the live person through to the caller. This probably would be some sort of smart JavaPhone application.
Likewise, the person being called should have one aggregator application that would fetch all SMS messages, emails, voicemails and call up the secretary on a regular basis to ask them to read off the day’s messages.