3GB - official carier not recognized after pwnage

Hi,

I bought a second hand 16GB white 3G in the US, which has firmware 2.2.1 and modem firmware 02.30.03. I used pwnage for Mac 2.2.5 to activate and jailbreak. My Belgian Mobistar SIM (official iPhone partner) does not work. When I enter pin it does not find a network. What am I overlooking ? My 2G phone works fine with official firmware and this SIM ?

Alain

Iphones are locked to a single partner. If it is an US iphone, it will only work with ATT