This paper presents experiments on a PR4 (Partial Response Class 4) transceiver aimed at using existing telephone-grade twisted pairs. The achievable loop length for typical line codes is first estimated for a wide range of bit rates, assuming that near-end crosstalk (NEXT) is the crucial degrading factor on TTPs. It is shown that a PR4 line code makes it possible to transmit 4 Mbps of data over a loop up to 450 meters long. A low-cost transceiver adopting a newly developed timing extraction method, called LDT (Logically Decided Timing extraction) , is implemented and evaluated. It is experimentally confirmed that 4Mbps transmission over existing TTPs was achieved in the presence of crosstalk and impulse noise.