Engage Voice meters calls per minute. The price per minute depends on the type of transport (such as inbound domestic, inbound toll-free, or outbound domestic) and the actual discount applied on the customer account. Suppose that the rate per inbound domestic minute is USD $0.01 per minute — in this case, Engage Voice will meter calls based on this rate. However, when you receive your bill, the invoice has aggregated the minutes and bills the minutes into 10-minute chunks. There is no rounding of call durations into ten minutes chunks.