ADSL splitter is different from telephone splitter. ADSL is using sub-frequency technology to transmit ordinary telephone lines to separate low and high frequency signal. Below 3400Hz of ADSL splitter is for phone; up 3400Hz of ADSL splitter is for Internet. That is using same copper wires to transmit data and voice signals respectively. But the data signal will not pass telephone splitter. It not only provide high-speed transmission but affect the normal telephone use when we are surf the internet at the same time. The function ofADSL splitter is separation telephone lines in the high-frequency signals and low frequency signal. It can be divide into two cases. First, ADSL work in full speed mode (FULL RATE), the phone transient noise (such as hook and hang up) will interfere with the operation of ADSL. In order to prevent this situation, you must install an ADSL splitter. Second, ADSL work in G mode in which the maximum transmission rate will be reduced, but it can save the user separation equipment. There are two forms of ADSL splitter. One  separator only has two interfaces, connecting outline and telephone line. Another is splitter for voice data.