Complex sentence: Disconnect Supervision is a term in telephony, describing a situation whereby the called party indicates to the telephone exchange that the call is being disconnected by the called party by allowing loop current to flow in the line.
Split into simpler sentences: Disconnect Supervision is a term in telephony describing signaling between the telephone exchange and a connected party used to indicate that the connected call is being terminated. For example the called party may indicate to the telephone exchange that the call is being disconnected by the called party by allowing loop current to flow in the line.