ITU V.61:1996
ITU V.61:1996 A Simultaneous Voice Plus Data Modem, Operating At A Voice Plus Data Signalling Rate Of 4800 Bit/s, With Optional Automatic Switching To Data-only Signalling Rates Of Up To 14 400 Bit/s, For Use On The General Switched Telephone Network And On Leased Point-to-point 2-wire Telephone Type Circuits