ADSL modems can create multiple channels to transfer data. For this, ADSL modems divide the available bandwidth of a telephone line in one of two ways - Frequency Division Multiplexing (FDM) and Echo Cancellation. The FDM assigns one band for upstream data and assigns another band for the downstream data. Further, the downstream path gets sub-divided into one or more high-speed channels by time division multiplexing. Similarly, the upstream path also gets multiplexed into corresponding low-speed channels. Echo Cancellation enables the upstream band to overlap the downstream band. These two bands get separated by means of local echo cancellation. Both Frequency Division Multiplexing (FDM) and Echo Cancellation techniques enable ADSL to split off a 4 kHz region for POTS at the DC end of the band. | 
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| The download speed ADSL provides is variable, depending on your distance to the central office or to a remote router. The maximum download speed of eight mbps is only possible if you live within one mile of the office. The typical ADSL subscriber can expect download speeds of up to four mbps. | 
