I tried to find a friend to train with me so we could do DTMF, or rather CCITT #5. I could whistle the 2400hz and 2600hz reasonably well (not at the same time)

I tried to find a friend to train with me so we could do DTMF, or rather CCITT #5. I could whistle the 2400hz and 2600hz reasonably well (not at the same time) which allowed me to hang up on international calls if I wanted to. Oh, I was also pretty adept at war-dialing manually in the dark. Dialing numbers in sequence, but then switched the light on and wrote down the details if I found a modem or a controllable voice mail or pbx system.