I upgraded to an iPhone 5 after my 4 fell into some water. The 4 works perfectly fine except for the ear speaker used during conversations. I figured I can still use the device as an itouch or give to a friend to do the same. Last night I was toying with it a little and noticed that if I take out the sim card its Wi-Fi becomes ridiculously slow for anything. Why is this happening? I thought the sim card only related to cellular usage and I am not understanding why taking it out it would slow down data transfers. I am leaning towards giving it to a friend but dont want them to have a painfully slow experience with it. If I give it away with the sim card, how do I ensure all data has been erased from both the phone and sim?