http://www.thephone.coop/home/phone-only/#/call_tariffsThis is interesting (to me at least).
The "Caller Plus" tariff has a lower rate for calling
local 01 and 02 numbers compared to that for calling
national 01 and 02 numbers. It's a while since I have seen a tariff with distinct local and national rates. I don't know if "local" means "same and immediately adjacent area codes" as used by BT long ago, or is restricted to just "same area code".
Additionally, calls to 03 numbers are charged at the same rate as calling
local 01 and 02 numbers. On this tariff, and where a distant company has both an 01 or 02 and an 03 number advertised, it is cheaper to call the 03 number than the 01 or 02 number!
03 is cheaper than 0870 at all times.
03 is cheaper than 0845 in the day and the same price as 0845 during evenings and weekends.
0870 is charged at the same rate as a national 01 or 02 call at all times.
0845 is more expensive than 0870 during the day.
0870 is more expensive than 0845 during evenings and weekends.
0845 is the most expensive during the day.
0870 is the most expensive during evenings and weekends.
03 is always the cheapest.
Calls to 0843, 0844, 0871, 0872, 0873 numbers look to be a couple of pence more expensive than BT's capped rates across the board, and a few pence cheaper than Virgin Media prices.