Bayonet-type locking and unlocking system for a circular connector with audible indicator of locking which comprises: - a socket comprising at least one lug; - a plug body that is inserted into the socket; - an external ring comprising an axial slot on the lower wall of the external ring, said external ring comprises at least one unblocking ramp; - an unlocking lug; - a locking ring comprising at least one locking ramp, said locking ramp is comprised of three parts, an axial part, a helical part and a circular part; said system is characterised in that it comprises: - in the axial slot of the external ring is inserted an intermediate washer driving the rotation thereof, and that the slope of the unblocking ramp is suitable for cooperating in the unlocking phase with an unblocking lug of a locking piece; - in the locking ramp locking ring slides in translation a lug of the socket; - the lug of the socket slides successively during the locking in the axial part, the helical part and the circular part of the locking ramp; - a locking piece comprising at least one blocking tooth, at least one unblocking lug and at least one guideway; said locking piece is mobile in axial translation with respect to the locking ring by the intermediary of the guideway and of a guide slot, the unblocking lug of the locking piece is suitable for cooperating with the unblocking ramp of the external ring in the unlocking phase only; - said system comprises an unlocking position wherein the blocking tooth of the locking piece is positioned in the guide slot leaving the lug of the socket free to translate to the helical part of the locking ramp; - said system comprises a locking position wherein the blocking tooth of the locking piece is positioned in the guide slot blocking the position of the lug of the socket in the circular part of the locking ramp; - an intermediate washer inserted into the external ring; said intermediate washer has a peripheral key linked in rotation by the axial slot of the external ring; said intermediate washer also has a side key linked in rotation by the housing of the locking ring in the locking phase. - a socket comprising at least one lug; - a plug body that is inserted into the socket; - an external ring comprising an axial slot on the lower wall of the external ring, said external ring comprises at least one unblocking ramp; - an unlocking lug; - a locking ring comprising at least one locking ramp, said locking ramp is comprised of three parts, an axial part, a helical part and a circular part; - in the axial slot of the external ring is inserted an intermediate washer driving the rotation thereof, and that the slope of the unblocking ramp is suitable for cooperating in the unlocking phase with an unblocking lug of a locking piece; - in the locking ramp locking ring slides in translation a lug of the socket; - the lug of the socket slides successively during the locking in the axial part, the helical part and the circular part of the locking ramp; - a locking piece comprising at least one blocking tooth, at least one unblocking lug and at least one guideway; said locking piece is mobile in axial translation with respect to the locking ring by the intermediary of the guideway and of a guide slot, the unblocking lug of the locking piece is suitable for cooperating with the unblocking ramp of the external ring in the unlocking phase only; - said system comprises an unlocking position wherein the blocking tooth of the locking piece is positioned in the guide slot leaving the lug of the socket free to translate to the helical part of the locking ramp; - said system comprises a locking position wherein the blocking tooth of the locking piece is positioned in the guide slot blocking the position of the lug of the socket in the circular part of the locking ramp; - an intermediate washer inserted into the external ring; said intermediate washer has a peripheral key linked in rotation by the axial slot of the external ring; said intermediate washer also has a side key linked in rotation by the housing of the locking ring in the locking phase.