Re: DTMF Sequences

Mar 05, 2006 0 Replies


Hi all!


> I wanted to know what sequences are sent when we press * and #.

Touch tones are also known as DTMF, or dual-tone multi-frequency. There are 4 "low" tones and 4 "high" tones. They combine, two at a time, to create the 16 standard DTMF signals. There's no sequencing involved in * and # - they're just two of the combinations.


The other 4 combinations, which you're not likely to have on your phone, are A, B, C, and D. I have them on an amateur radio Handi-Talkie, where they might be used to control radio repeaters. They were originally intended for military use. See .


also, what sequences are sent for international calls? what happens
> when the sender tries to morph his identity ?what sequences are sent > in such a case?

You may be thinking of trunk signaling, which I know nothing about.


Jack Hamilton California


Qui vit sans folie n'est pas si sage qu'il croit. François VI, duc de La Rochefoucauld

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