The FOI-4605 provides complete electrical isolation for 4-wire S/T-Interface ISDN communications. The unit 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.

A typical link consists of two FOI-4605, one at the network terminal and another at the terminal equipment with a duplex fiber optic cable between them.