this is interesting, cause delivery reports work on my fone, and im on o2, but as for the network, there is plenty of space as there are roughly about 50,000,000 text messeges going through the o2 network each day, and that isnt even a fraction of what its capacity holds, and im sure if they wanted it, the cost wouldnt break the o2 bank balance.
so as i work for o2, i can tell you that reports do work on the o2 network!!!, either that, or my fone is one of a kind!!!!