On your bill, directs you to
http://www.ntl.com/home/telephone/tariff.asp
From the 01 September 2004 the cost of calling 0845 and 0870 numbers is changing.
0845 4.50p daytime, 2.25p evening, 1.45p weekend (OUCH!)
0870 7.99p daytime, 3.85p evening, 2.99p weekend
0870 are a stinking ripoff anyway -
http://www.saynoto0870.co.uk