This is a running count of cells that had to be substituted on this circuit emulation connection, typically to fill gaps from lost or late cells and keep the emulated bit stream continuous. An admin treats a rising count here as a warning sign of underlying cell loss on the ATM path even though the circuit emulation kept running smoothly. For example, an increasing qbCESStatsReplacedCells count on a T1 circuit emulation link indicates the ATM network is dropping cells that CES is compensating for to avoid a service outage.