i realise that i'm probably the last person to suss this out.
But i've been meaning to call bt for months now to get home calls diverted to my mobile. I only ever remembered when i was out at work.
But i remembered earlier and went on the net to look and i found this site that tells you how to do it.
www.telephonesuk.co.uk/network_codes.htm#BTCDIV
Have just gotta remember to have a little book and pen on me now.
I believe that BT do charge a monthly (or quarterly) fee to provide Call Divert and the numbers you have linked to are indeed the ones that are used for it. Ideally I would like to prefix the number to which I divert with the number that I use for most of my calls but BT don't seem to allow this. It looks like you have to divert without a prefix (which would usually give you a cheaper deal). I actually think this is wrong because BT are still enjoying a monopoly on calling the number to which the call is diverted. If there was no monthly charge this might just about be acceptable but there is, so it isn't.
Also, you won't need to carry that book and pen with you. You cannot switch Call Divert on and off remotely. You have to do it from your landline phone.