This object specifies the backward signal indicating the called party's line is free but that the call should not be charged upon answer. This is the toll-free counterpart to ccasBwdRSSubLineFreeWithCharge, so the two signals together determine whether a completed call generates a billing record at all; a gateway that cannot distinguish them risks billing calls, like emergency or toll-free numbers, that should be free. A call to a toll-free customer-service number would typically be answered under this signal rather than the charge-on-answer variant, so no billing record is generated for that call.