When I was in college, I built the most advanced telephone answering machine in the world. The year was 1985, and it employed synthetic speech for the outgoing message, and used Touch Tone (r) decoding for the various functions listed below, some of which are still not commercially available.
Salient points of the design:
1. The speech synthesis (SC-01 chip, if you must know) also added a verbal date and time stamp at the end of each caller's message, so you'll know upon playback when the call came in. (Nobody ever leaves the time they called when you ask them to.)
2. Priority Message Taking Feature - Priority callers can Touch Tone in a pre-assigned 4-digit code in lieu of a verbal message; the caller then gets a personalized "Thank You", (i.e., "Thank you, Nancy"), and a phone message containing the first and last name, phone number, time and date is instantly printed out, resulting in a printed list of priority clients whose calls should be returned first. (Non-priority callers will just have to wait until you get around to listening to their taped messages.)
4. Extremely Remote Control--This system also allows you to turn up to five A.C. appliances on or off from anywhere in the world just by entering the proper 4-digit Touch Tone code. Verbal confirmation and the status of the device (i.e. "Device number 1 is off.") is announced.
5. Outgoing Call Monitor--When the user is at home, the system doubles as an outgoing call monitor, where the time, date, and number dialed from any Touch Tone extension phone is automatically logged, providing a hardcopy record of all outgoing calls so they can be checked against the Phone Co.'s bills.
The whole thing was controlled by a Hewlett Packard 41C calculator (not shown in the top photo). Also not shown is a thermal printer and a cassette recorder. The whole thing still works, but I'm having trouble with my HP data cassette drive.
