A communications station (4-i) for a WDM ring network is adapted to insert into an optical fiber (2) packets of optical signals carried by at least one wavelength and having a propagation direction in common with at least one other communications station. The station (4-i) comprises, firstly, optical detection means (17) adapted to observe the traffic in said optical fiber (2) associated with said common wavelength and to deliver detection signals representative of the absence of packets in the optical fiber (2) at the detected wavelength for a duration exceeding a duration threshold and ii) control means (11) adapted, in the event of reception of a detection signal associated with the detected wavelength to determine the remaining time before the end of the current session, and then to instruct the insertion into the optical fiber (2) of a packet awaiting transmission, at the detected wavelength, if the remaining time before the end of the current session is greater than the time necessary for inserting the packet awaiting transmission into the fiber.