For future reference, there is no SIM card on CDMA-based phones (i.e. phones from Verizon, Sprint, Alltel, MetroPCS, etc.). In any case, I have the n900 sitting on my desk right now without a SIM card inserted. It works perfectly fine on my wifi network. I will be ordering up a data-only SIM card in about two weeks for road testing. If you are interested in what I'm doing, here's my post: http://talk.maemo.org/showthread.php?t=43723