The Telephone Enquiry Service is a computer system which allows interactive information retrieval from an ordinary touch-tone telephone. For input, the caller employs the touch-tone keypad, and the computer replies with a synthetic voice response. The service has been in fairly continuous operation for around one year, using a small time-shared computer in conjunction with an internal 200-line telephone exchange, and has been widely used by people with no special interest in synthetic speech. An unusual feature of the system is that the speech is generated by rule from a phonetic representation. A satellite computer, acting as a peripheral to the main machine, performs this task in real time, and controls the parameters of an analogue speech synthesizer. This constitutes an extremely economical and flexible method of speech storage, whose only real disadvantage is the low quality of articulation of the output. A major conclusion of the work is that even low-quality speech is acceptable to casual users, if the service is sufficiently interesting and useful to them.