Won't recognise sim

Recently my Iphone 3GS came up with the message to connect to ITunes. So that afternoon I connected it and it said that there had been an error and that it needed a system restore. So I did the restore but now when trying to configure the phone it won't recognise the sim card. This sim still works in other phones and is obviously an error with the Iphone. I can't do the restore again as when I go to Itunes it says there is no sim installed so I cant do anything at all.

Any help would be muchly appreciated!