User:Chicolatin

M2M= Movil To Movil ;Used in cellular tecnology,when you have a cellular phone communication between Movil or cellular phones. M2MCNG = Mobile to Mobile from AT&T phone to Cingular phone

Even though AT&T owns Cingular, and the Cingular name is no longer used, some people still have Cingular sim cards (I do) and so when you call them it shows up as M2MCNG. Same can be true if they have their original Cingular phone number (again, I do). Even if the number is associated with another carrier now if the person kept their number when switching carriers, because the number was originally given to Cingular. Cingular content is still used by AT&T (tethering, for example), and is the reason that Cingular hasn't been completely done away with, plus some people don't have any reason to change their sim cards.

Both should be free, and if you are being charged for the Cingular calls (M2MCNG), then you need to call AT&T and have them reimburse you. They shouldn't be charging you, but it is known to happen.