I am making a repeater controller for an Amateur Radio repeater. The program is working well - it has a pause at the end of a transmission and a Morse code ID comes on after the repeater has been in use. A Zarlink MT8880 DTMF decoder is used to provide additional controls through DTMF tones. For example, one tone (an "A" on a DTMF pad) causes the circuit to read the battery voltage and send it back via Morse code. Other single digit tones will be used to read out temperature, turn the transmitter on and off, and turn on or off an additional relay. Instead of using one tone to give access to these functions, however, I would like to use three tones that must be provided in the correct sequence so that someone doesn't accidently get a result that is different than intended. Unfortunately, I don't know how to do this and after spending a lot of time trying I still don't see an easy way. I would certainly appreciate any suggestions that would be helpful to overcome this problem. I have attached the relevant section of the complete program. It is adapted from the Parallax AppKit "Using the CM8880 DTMF Transceiver, and the place where I am having trouble is right near the end where it says IF dtmf = %1101 THEN GOSUB Voltmeter, etc. Just one tone is required and I would like to require three in the correct sequence.