The EM91401 is a series of tone/pulse switchable dialers that is composed of T/P dialer. The EM91401 series provide necessary functions of telephone set for application in any environment, such as Pulse dialing, Tone (DTMF) dialing, Handfree dialing, keying tone ,and lock functions. The lock function is designed to inhibit toll dialing operation. Beside this, melody generator, ring detector and SDO (Serial Data Output) functions are provided in advance version. Melody generator will output dual-tone music in line hold duration. Ring detector can prevent illegal dialing from pocket dialer. The SDO is designed to drive LCD driver and voice synthesizer. In this application, the dialing numbers can be displayed on LCD screen with EM32100 ( or EM32116 ).