This read-only DisplayString, up to 255 characters, holds the Calling Party Number information, such as that passed in an ISDN SETUP message by a PBX or switch for incoming calls, used to identify the peer; it is zero-length if unknown or identical to daWanConnectionLocalAddress. An admin uses this to identify exactly which remote number placed an inbound call on this connection. For example, an admin investigating an unexpected inbound connection could read this field to see the actual calling number reported by the switch, rather than relying on the configured peer device's descriptive name.