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June 1, 1980 · TAP

TAP No. 63 - How to Modify Your Bell Touch Tone Fone to Have 1633 Cycle Tones

TAP No. 63 - How to Modify Your Bell Touch Tone Fone to Have 1633 Cycle Tones

‘The Sagician’ follows up on a prior issue’s discussion of 1633 Hz signaling tones (used for toll-free loop-arounds, mass conferencing, and Autovon access) with a step-by-step hardware guide for adding the missing fourth column of DTMF keys to a standard Bell touch-tone phone. The mod requires only a miniature SPDT toggle switch and hookup wire, wired into the touch-tone pad’s toroid transformers after opening the handset housing, letting the phone generate tones that consumer keypads normally omit.

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