I have recently bought a Pearl 8120 on the o2 network, and am very pleased with it. It's great.
However, I think it should be capable of operating on an EDGE network, at least it says so on o2's own specification site for the phone. I know that I am in an area with coverage as I have been able to get it on other phones. Is there an option I need to enable, or am I overlooking something that's starring me in the face?!
My signal constantly alternates between EDGE and GPRS. It all depends on the signal strength where you are. I get an excellent EDGE signal on the train for example.
There is nothing you can do to change it I don't think.
It does appear a little odd but perhaps the blackberry picks up the stronger of the two signals. I honestly don't know the nitty gritty details of it all.
I read somewhere that EDGE was not supported on the 8120 on o2, but I'm not sure if that's right, particularly since their own site lists it as a connection for the phone. I might have to go on a day trip and see if it works elsewhere!
My 8120 which has an O2 logo (I'm on the IOM, with manx telecom which are owned by O2) I have picked up edge in the England but I never really payed attention to how it switched.