Billing increment is the way we (and the telecom industry) calculate our rates in order to bill your calls. For example, if you call the Unites States for 10 seconds, you will be charged for 12 seconds (call minimum is 6 seconds, and 2(x)6 seconds since this is a 6 second increment call), instead of the full minute.

If you call Mexico for 10 seconds, you will be charged for 1 whole minute (60 seconds minimum call charge, 60 second increments).