What are Unlocked Gsm Cell Phones?

I-MATE JAQ UNLOCKED PDA Retail Price: $499.99 Sale Price: $169.99 You Save: $330.00

NOKIA N76 PEARL BLACK (UNLOCKED) Retail Price: $849.99 Sale Price: $499.98 You Save: $350.01

MOTOROLA RAZR2 V8 BLACK (UNLOCKED) Retail Price: $544.95 Sale Price: $429.98 You Save: $114.97