Yes, Pix, I have read the post from Ivann:)
When I am saying ‘modem’ I am imaging device supporting data transfer over the telephone network according ITU-T V-series recomendations. When I am saying ‘DTMF’ I am imaging a device on user side that supports DTMF-alphabet (8 frequencies from voice band by means of which the figures from 0 to 10 and (#,*) symbols are encoded)….