The condition that arises when a telephone line or trunk is seized at both ends for different reasons, perhaps causing the collision between an incoming call and an outgoing call, for example. Glare is a phenomenon associated with loop start signaling used to support single-line telephones, multi-line telephones, and key telephone systems (KTSs).When the handset of the telephone is lifted, the electrical loop is completed and current flows across the circuit.The central office switch detects that fact and returns dial tone for an outgoing call, or connects an incoming call, as appropriate. If the user picks up the handset to place an outgoing call at the same time that the central office switch is attempting to connect an incoming call, a collision, or glare condition, occurs. See also ground start, loop, and loop start.