I came up with this idea after reading a similar idea in the letters section of Consumer Reports and I think it would be such a boon for those that go over their minutes all the time. Like pre-schoolers, pre-teens and teenagers
Here's how it would work:
Thanks to the technological advancements by the likes of Bell Labs and Lucent Technologies the system used by your phone service would record enough of your conversations to fully analyze and then technologically mimic your voice. The reason for this is so the system can then break into the call in your voice, temporarily cutting you off from the person you're talking to, yet she or he would not know the difference. It's your voice after all, including the right inflections, tone, colloquialisms and so on. Only you would be making a 15-25 second advertising spot to defer the costs of going over your minutes. When your computer doppleganger is done, you would be allowed to return to your call, assuming the person on the other end hasn't hung up in disgust.
The system would do this for incoming calls, too. So, until you learn how to mind your minutes or pay for more in a timely manner, you would be subjected to all the advertising needed to offset the added fees to your bill.