Other phones can even get the tag from the tower.  These are common
in China.  China SIMs are usually charged differently depending on
whether the phone is being used in its "home" area or somewhere else,
so the towers typically broadcast an alpha tag which includes the area
so you can tell what you'll be charged.

One US phone I've had was capable of displaying those tags from the tower,
though I can't remember which.

Dennis Ferguson