Iridium Extreme - SIM Card Error - Insert a Valid SIM card

This error is most commonly caused by the SIM Card tray not being locked into position. Once you have placed the SIM in the door, and the door hinged back into the phone, you must slide the tray into a locked position. There is an arrow on the SIM tray indicating the way to slide to unlock/open the tray. Sliding the tray opposite the arrow will lock the tray.