Universal Personal Telecommunication (UPT) - Access devices - Dual Tone Multi Frequency (DTMF) sender for acoustical coupling to the microphone of a handset telephone
This I-ETS defines the tone generating and acoustical characteristics of a one-way (sending) Universal Personal Telecommunication (UPT) access device of Dual Tone Multi Frequency (DTMF) type to be acoustically coupled to the mouthpiece of a telephone set. The characterics specified have been chosen to conform to the transmission requirements as specifies in ETS 300 001 and therefore, to be generally acceptable for use in the Public Switched Telephone network (PSTN) and Integrated Services Digital Network (ISDN).