What will show up on my caller ID?
This answer varies on the facility, but most will show up as "Unknown," "Unavailable," a series of zeroes, or "Out of Area." So, go ahead and answer those calls until you learn which ones are from your loved ones. If it's a bill collector or a telemarketer, you can always hang up, but we know no one wants to miss those calls!!
Here in California, CDC uses globaltellink and my caller ID says "GTL".