How to restore iPhone backup without a SIM card?

So a while back my sister gave me her iPhone as she was getting herself a new phone. I had been using this iphone without a sim card and had no problems, except the memory was getting pretty full so I backed it up and planned on doing a factory reset and then restoring my phone from the backup. I used to do this with my iPod many times and it worked without a problem. Only thing, after the phone had been completely restored I realized that it can t connect to iTunes if it isn't activated, and I can t do that without a SIM card. I m kind of freaking out here because I have no other way to access anything and I'm wondering if there's any way to restore my backup without having a SIM card???