The FOI-2971 and FOI-4972 provide complete electrical isolation for 2-wire telephone communications. The FOI-4972 supports standard analog phones, STU-III (secure telephone unit) phones, STE (secure telephone equipment) phones, fax machines, and modems and supports Caller ID.

The units can be used in areas of high electrical noise or in and out of RF shielded enclosures. The fiber optic cable is not susceptible to interference caused by impulse noise, crosstalk, or EMI. Privacy of communications is also enhanced because the fiber optic cable does not radiate any emissions. FiberPlex recommends “R” units for high security applications because the units have added filtering and shielding for RFI suppression.

In addition, fiber optic cable offers much longer transmission distances than traditional telephone line cord wiring. Multimode optics on the units can extend the distance to 2km, while singlemode optics can further extend the distance to 20km. A typical link consists of an FOI-2971 connected to the POTS line and an FOI-4972 at the subscriber’s phone with a duplex fiber optic cable between them.

Flexible Mounting and Powering Options

The FOI-2971 and FOI-4972 are part of the FOI line of products designed for ruggedized mil applications. They are housed in the familiar FOI shielded can enclosure. For standalone applications they can be powered by adding a PSQ‐4909 AC supply or a PSQ‐4920 DC power supply (not included). Optionally, up to 8 FOI units can be mounted on CMA chassis adapters and installed in an RMC‐3101 or RMC‐2101 rack mount chassis. The units are powered redundantly by a common back plane connection.

Parameter Name	Parameter Value
Signal type	analog electro-optical
Other characteristics	for fiber optics