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)… ...

When a DTMF tone is received, a NodeMCU connected to the decoder calls an IFTTT job to echo the key to [WTH]’s phone as an SMS message.

Winston-Salem, NC&#8212CML Microcircuits' CMX867A, a V.22 multi-standard modem IC for telephone-based information systems, includes an enhanced DTMF decoder, thus affording a more compact design and ...