I bought a new Sony Ericson Vivaz Pro. I tried to use it without a SIM-card but that was not possible. My old phones I could use when the SIM-card was not in the phone.
The reason I ask is that I was in Japan and my SIM-card and phone did not work there and when I removed the SIM-cartd I could not use the phone for wifi and pictures as the phone insisted on a SIM-card.