Telephone cable is CW1308. Its not "CAT anything". The thin crappy stuff thats not really recommended for long lengths is CW1311CW1308 has 2 pairs and is usually connected to a UK telephone plug or RJ11 (4 pins) CAT5/6 is designed for ethernet & has 4 pairs for connecting to an RJ45 (8 pins)
Quite often CAT5 cable is recommended as the ideal cable to use for ADSL wiring. CAT 5 cable is a twisted pair cable so it is perfectly suitable for the purpose of ADSL. CAT5 cable is designed for Ethernet networking applications that run at much higher frequencies and higher data rates than those of any variant of ADSL. As a result the wire used is thicker and the cable has a higher number of twists per meter than CW1308 cable as it is required for the higher frequency signal. Similarly CAT6 cable has even more turns per meter and even thicker wire is used to account for gigabit Ethernet speeds. There is very little benefit in choosing CAT5 or CAT6 cable over the standard CW1308 cable as the extra twists will not benefit the ADSL signal. CAT5/6 cable is much bulkier than CW1308 as it typically has 4 pairs (8 wires) and is usually supplied in a grey finish making more difficult to hide. Our recommendation is that if you are already installing CAT5 cable for networking and are able to hide it away then it there is no harm in using it for ADSL extension wiring at the same time as you probably have bought a drum of it and have some spare.
