Not sure if I am missing something, but I won't use a company that tries to con it's users, (non of those numbers are "national rate").;-
"Call Internationally for as little as 4p per minute using our two national rate numbers
0871 504 0700
7 days a week.
0870 068 0700
Weekdays only."
http://www.pre-dial.com/ 0870 0680700;- * This is classified as a Special Services higher rate: BT’s Standard National Call Retail Price for BT customers number. (insert by me, these will cost 6ppm daytime).
* It is provided by Magrathea Telecommunications Limited.
0871 5040700;- * This is classified as a Special Services higher rate: up to and including 10p for BT customers (non-internet) number.
* It is provided by Magrathea Telecommunications Limited.
*
And costs 10ppm [in pence or pounds where 'pm' means 'per minute' and 'pc' means 'per call'].