An adaptor for connecting the conventional plug which connects a telephone handset to a modem so that a computer connected to the modem may be operably connected to the transmitter circuitry associated with any conventional dual tone multiple frequency (DTMF) telephone....http://www.google.fr/patents/US5059141?utm_source=gb-gplus-shareBrevet US5059141 - Modem/telephone handset cord adaptor
