Fixed Network short messages is one of China Telecom opened through the fixed telephone net sending and receiving short messages business. Dedicated  SOC chip of fixed network phone for short messages is the dedicated microprocessor chip (referred to as SMS-chip) of fixed network  phone terminals for short messages . Its embedded in an 8-bit microcontroller (MCU, Microcontroller Unit), and integration of a telephone caller identification information transmission module (CID, Calling Identity Delivery) and dual tone multi-frequency coding module (DTMF, Dual Ton e Multi Frequency), so that fixed network  phone support  to receive and send short message in the fixed network SMS platform.

     Through hardware design and simulation of the DTMF signal generation module of fixed network SMS-chip (hereinafter referred to as SMS-SOC), this design try to explore the design and simulation method number of FPGA-based SOC chip mixed-mode to verify results. The  overall design Of SMS-SOC is based on  SOC design technology in the top-down design process, the design of DTMF is the use of this method, of course. The design of the DTMF overall is divided into three major parts: the frequency of the controller module, sine wave generator modules, frequency synthesizer module. Which the frequency of the controller module and the sine wave generator module design in Quartus Ⅱ in the completion of the direct use of VHDL language, frequency synthesizer module of the device directly call Library. And then each module and overall simulate in the Quartus Ⅱ  environment, but because of DTMF signals on the network based on analog signal transmission,the final design will be carried out overall in the ModelSim simulation to see the final wave.