With v2.3 of the Spectracom NetClock Model 9183, users can choose from three oscillators, each of which provides holdover to keep the local time standard on time in the case when the GPS system is turned off, or if the user's antenna is out of service. Another new system reliability feature in NetClock v2.3 is an optional dial-out modem that serves as a backup to GPS. With the modem option on, and the NetClock operating on its local oscillator such as Rubidium, NetClock v2.3 detects the leap second change from National Institute of Standards and Technology (NIST) via dialup, so all devices relying on NetClock for time synchronization also pick up the leap second change at the same time.
