This read-write object indicates whether to accept and transfer the Calling Party Subaddress Information Element, and the description notes it only takes effect if calling party number delivery is also enabled. Because this subaddress delivery is explicitly gated on ciscoatmSigSupportClgPtyNumDel already being enabled, turning this on while number delivery is still disabled has no effect, a dependency easy to overlook when troubleshooting missing subaddress info on the far end. An admin enabling this object but forgetting that ciscoatmSigSupportClgPtyNumDel is still disabled on the interface would see no subaddress delivered to the called party at all.