I cancelled SIM unlock and now I cannot unlock the device

When I inserted SIM card into my phone I tapped the "cancel" button, assuming that it would be possible to unlock it later. But I fear that my assumption was wrong. The device is a **Sony Ericsson XPERIA X8**. Sadly I cannot find anything in "Settings" to unlock the SIM. I have tried removing and inserting the SIM card several times, but it doesn't help. Somehow the devices remembers that I selected cancel. I'm not seeing any prompts related to unlocking the device. ---- I can see that the APNs page is empty. There is no Add button on it. Settings -> Wireless & network settings -> Mobile network settings -> Access Point Names ---- Mobile network state Disconnected ---- Firmware version 2.1-update1 ---- Build number 2.0.1.A.0.47 ---- Model number E15i ---- Is it hidden in another app or is there something I have overlooked?