iPhone Reception

There are three iPhones in my household, two 3G's and 1 3GS. Does anyone know why the 3GS suffers significantly poorer reception than the other two? It would be great to have a bit of knowledge before I ring O2 and complain. Frequently I have no reception at all and the other two iPhones are just fine. And this in London. Thanks

In December I got a 3GS on O2 having not previously had an iPhone. I have patchy reception in places and put it down to holes in the O2 network rather than problems with the handset.

I'd agree that indoors the 3Gs does seem to perform a little poorer than the 3G.
Not really seen much of a huge different out doors though.

However.. I switched to Vodafone and go the Suresignal.. not 100% in the house all the time.