Abstract: Since a high-speed demand for data transmission is required, Digital Subscriber Line (DSL) is a technology that provides a very high-speed digital data transmission using the regular telephone lines as the transmission media. The most promising of the xDSL technologies is Asymmetric Digital Subscriber Line (ADSL). ADSL was developed to offer a unique service to transport multi-phone line by combining number of plain old telephone signal (POTS) with a moderateamount of data to the client where this service known as Channelized Voice over DSL (CVoDSL). In this thesis CVoDSL system was designed based on a physical layer of ADSL modem with noisy channel where the voice of the telephony signaling is digitized and carried over the DSL physical layer along with the data traffic. The voice channels are multiplexed into the DSL path using a combination of frequency and time division multiplexing. The physical layer of DSL modem was implemented using Discrete Multitone (DMT) modulation technique which makes efficient use of the channel, and maximizing the throughput by sending different numbers of bits on different subchannels. This thesis also investigates the effect of using turbo coding as forward error correction (FEC) with different code rate and find its ability to enhance system performance by using soft decision demodulation (Log Likelihood Ratio LLR) instead of the ordinary hard decision. CVoDSL systems was implemented using Matlab simulink V.(R2007a) to investigate their performance in supplying four telephone lines, where the minimum Bit error rate BER(0.0001833) at signal to noise ratio SNR (32.3) which is considered as the highest value compared with other users. The Turbo code results have shown remarkable coding gains by achieving 8dB from uncoded system for data performance and also achieve 3 decimal points as BER enhancement between first and sixth iteration.