A handy plastic opening tool helps separate the SIM card reader from the rest of the motherboard.

The Nexus S is unlocked right out of the box and can be used with a Quad-band (850, 900, 1800, 1900) GSM carrier and is Tri-band HSPA (900, 2100, 1700) compatible.

For you AT&T customers out there, just a quick reminder that the Nexus S does not support the 850 MHz and 1900 MHz HSPA frequency bands required for 3G mobile data.