While many of us have banished land line telephones from our houses, there are still quite a few people who utilize POTS lines today. These analog phone systems use Dual Tone Multi Frequency (DTMF)… ...

Though many of us will never have experimented with it, most readers should be familiar with DTMF as the tones used by the telephone system for dialling. If your youth was not misspent mashing 4-4-… ...