Mobile phones > Sony Ericsson > C510

I bought the Sony Ericson C510 phone on eBay. The phone was originally on the 3 network but was unlocked. I put my 02 contract sim-card into the phone, and had big problems trying to get the phone to receive picture messages and work with the internet.

Eventually I got the phone to receive picture messages but it meant that I had to change the firmware. The next problem I had was that now I’m on the sim-free firmware, the phone regularly says "inactive sim" where it would normally say o2.

I took the phone to the o2 store, and they gave me a new sim-card, however that didn’t fix the problem. The guy at o2 suggested that the reason phones say inactive sim is because of a firmware problem. The phone will typically display this message about 5 times a day, and almost always does it when phoning someone.

I have no idea how this problem can be fixed, as far as I know there isn’t any way to install the o2 firmware onto the phone without paying £45 at car phone warehouse!

Any help would be much appreciated.