wanted: return caller program

[JDEBE at MTUS5.BITNET]

An alternate solution to you problem that you may want to consider is a
callback modem. We have one here at Michigan Tech.

The way it works is as follows:
        1) The user calls the modem.
        2) The modem asks for a userid, password combination and hangs up.
        3) If the userid, password combination is valid, the modem calls
           back to the userid's registered phone number and prompts for the
           userid, password combination again.
        4) Upon verification of the combination the connection is then passed
           thru to the host.