The TMX-4815 provides complete electrical isolation for ISDN S/T-Interface and T/E carrier communications up to E2 data rates. The unit is transparent to all AMI (Alternate Mark Inversion) signaling regardless of the specific line encoding, such as pseudoternary, B8ZS, B6ZS, and HDB3. However, the maximum data rate must not exceed 8.448 Mbps because of sampling jitter. The unit has four independent channels with two switches each that allow users to select between different pinouts and interfaces. If the signal received by the far-end equipment is too strong, the TMX-4815 can reduce the transmit level by entering additional attenuation.

The unit can be used in areas of high electrical noise or in and out of RF shielded enclosures. The unit enhances privacy of communications because fiber can not be tapped without being detected and does not radiate any emissions. The fiber optic cable is not susceptible to interference caused by impulse noise, crosstalk, or EMI. The potential problem of creating ground loops or ground offsets is also eliminated because signal ground is not carried over the fiber.

In addition, fiber optic cable offers much longer transmission distances than copper wiring. The distance limitations for both T1 and E1 as specified in ANSI T1.403 is 6200ft (1890m) for T1 and 4800ft (1460m) for E1. However, multimode optics on the TMX-4815 can extend the distance to 2km, while singlemode optics can further extend the distance to 20km. A typical link consists of two TMX-4815, one at each end of the network with a duplex fiber optic cable between them.