This object specifies the backward signal an R2 incoming register sends to indicate it has all the address digits it needs and is now switching over to receive Group B signals, which convey the called subscriber's line condition such as busy, free, or out of order. This signal marks a specific state-machine transition in R2 register signaling, from digit collection to call-outcome reporting, so if it is misconfigured the far end may keep sending address digits the gateway is no longer listening for, or the gateway may never learn whether the called line is actually free or busy. After collecting a complete 7-digit DNIS, the gateway sends this backward signal so the originating exchange knows to stop sending digits and instead await a Group B signal reporting the called subscriber's line status.