Does kt 3170 & mt 8870 can decode key press events?

[vinodquilon]

dtmf ic

Does these dtmf ics kt 3170 & mt 8870 can decode key press events while hearing ring-back tone (RBT) in on-hook state before accepting call. If no, does any other dtmf ics can do this?

 

[betwixt]

Re: dtmf ic

They are nothing more than tone decoders. If the tones are present in the on-hook state and you have suitable coupling to the line, they will work. DTMF decoders normally have on-board bandpass filters to ensure only the high and low tone groups are monitored, other tones on the line will be ignored.

Brian.