Michael B. explained :
> I am going to be travelling to London for 8 days. I would like to get the
> CHEAPEST possible pre-paid SIM card for while there. Anyone with
> suggestions? I really only need to RECEIVE calls and yes, my phone is
> UNLOCKED.

It makes no difference whatsoever which Network you use if all you will
be doing is receiving calls.

If people are ringing you it'll be them paying all the charges.

If people will be ringing you from the UK from their landline, it would
make sense for you to have an O2 sim - O2 may be cheaper for them to
call.