Young mathematicians dive into the number line to discover decimals and how the numbers infinitely get smaller in between. They click the zoom button a few times and learn that the number line doesn't just stop at integers. Includes a...
But maybe you're not sure exactly what that means. An unlocked cell phone is one that is not tied into a certain carrier's network: It will work with more than one service provider. Most cell phones and smartphones are tiedâor lockedâto a certain cellular carrier, such as Verizon Wireless, T-Mobile, AT&T, or Sprint.
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.