This is a read-only text field storing the peer address in the reversed call direction: for an ingress, or inbound, call it holds the called number, and for an egress, or outbound, call it holds the calling number, with a zero-length value if that address isn't available. An admin uses this to see the other side of the addressing for a call depending on its direction, useful for call-detail analysis where the normal calling/called fields alone don't give the full picture. For example, an admin analyzing an outbound call's routing behavior would check this field to see the calling number the far end will perceive, alongside the standard destination address.