The XC-2 bi-directional DTMF to ASCII Transceiver Board converts DTMF decoded from an audio source to ASCII, which is transmitted via the RS-232 serial data port. It also converts ASCII received from the RS-232 port to DTMF, which is then transmitted on the audio line. RS-232 connection: DB-9. Audio In and Out: 3.5mm audio jacks The XC-2/C in enclosure with the DB-9 M/F cable, 2-3.5mm audio cables and PS-12 power supply. Size: 4.25"x3.00"x1.50"