This read-only string reports the Automatic Number Identification, essentially the caller's originating phone number, for the call currently active on this port, valid only while connected. Admins use it for live call tracing, such as confirming which caller is tied up on a given port during a support investigation. For example, if a customer calls in reporting a stuck call, support staff can match the reported number against currentAni across the port table to locate exactly which port is handling that caller's session.