Cell Parts. Your body is made of about 10 trillion cells. The largest human cells are about the diameter of a human hair, but most human cells are smaller -- perhaps one-tenth of the diameter of a human hair.Run your fingers through your hair now and look at a single strand. bacteria is a single, self-contained, living cell. An Escherichia coli bacteria (or E. coli bacteria) is typical -- it is about one-hundredth the size of a human cell (maybe a micron long and one-tenth of a micron wide), so it is invisible without a microscope.
A cellular phone that uses the Global System for Mobile (GSM) network and can access multiple cellular phone service provider networks is called an unlocked GSM phone. A locked cell phone is sold by the cell phone service provider and cannot be used with any other provider.
For example, if AT&T paid for the phone, AT&T would lock it so it could only be used on AT&T and not T-Mobile. This lock is called by several names including: Sub Lock or SPC Lock or Sim Lock. Now that you know why the cell phones are locked, I will discuss how to tell if your cell phone is locked or unlocked. First, you must determine if your phone is a GSM phone or a CDMA phone. This is easy to tell, if the phone uses a sim card (a small piece of plastic that you put in the phone, see picture below), it is GSM, if it doesn't, it is CDMA.