BT reference number CW1308 specification twisted pair telephone cable. Solid tinned annealed copper cable suitable for ADSL & normal telephone use. Black outer insulation, 2 pairs. INDOOR USE. Use 5mm cable clips. Sold by the metre & supplied as a SINGLE length, eg, ordering a qty of 10 will mean you receive a single 10m length!
Attenuation will be worse in Copper Clad Aluminium cables due to the higher bulk resistance of aluminium. This provides the risk of greater data loss, as more packets have to be retransmitted. Only use pure copper cable!