Looks like those Ambrosia Guys have made a break-through. This video shows their iToner utility working with the iPhone 1.1.1 firmware. iToner, as you may already know, allows you to install third-party ringtones onto your iPhone. So you can either use your personal audio collection or record your Mom saying "Pick up the phone!" and play that whenever she calls.
The 111-compatible update to iToner is still in beta but as this video shows, it should be arriving soon.