I thought you answered questions, not asked them!

;-)

For 0845, 0800 calls use pre-dials 07 access number, using your inc
minutes directly.
For 0870 calls, you could clock up some points/units from your ED50 to
your three number, then use a geographical access number to make a call
from three using qxdial+ at www.qxcall.co.uk and/or use the callback
service using same account/units. (though this access method would cost
you more units per/min)

You will have to confirm that callback will work to a three number
though, but if seriously thinking about using the callback from three,
I suggest changing it/port in an O2/Orange number as it's cheaper for
the system to call. (or use callback from your ED50 directly for peak
times)

There is a geo number to clock up points though it's a very small
amount per/min.

Another option is, if you prefer using pre-dial on ED50, get the points
earned transferred on request to your three number, then use their 0800
access number, but prefixed with an 01/07 call through on three to call
the 0800 access number, thus costing nothing to access pre-dial on
three, though I would not recommend this option due to cost
consideration being high per/min for the 0845/0870 end call. It
wouldn't be so bad if pre-dial had a geo access number, but they
don't.

Assuming to still have/use ED50, and obviously you would dial direct
from you ED50 for any off-peak 0845/0870 calls you make.

It really depends on your usage, amount/length of 08 calls, time of
day, and were you have excess minutes that are not getting used, I've
given a few ideas above though some methods cost more that others, the
best option will always be the one which costs the least and makes the
best use of your minutes, but does not rule out using a mixture of
services above depending on the type of call and length to suit your
needs.

Forgot to mention you can use qxdial for 0800 (at low cost), 0844, and
0871 calls as well : - )

Dan