iphone 2g and sim use

Hi,

I jailbreaked and unlocked my 2g iphone...all seemed to go successfully i.e. no errors.

I am now able to use all features of the iphone...but the sim is not been recognised so i cant make calls.

I just want to ask...if you unlock and jailbreak the 2g iphone can u insert any sim into the iphone which will automatically be picked up...or do u have to activate the iphone when the sim is put in. Its just that i thought the iphone would work in the way a normal phone works where u can put in sim after sim and they are automatically picked up without needing to connect to a pc.

Thanks...