Mount the Dual Provider Inline Switch near the distribution device (see fig.1). If there is an alarm-dialing device the Dual Provider Inline Switch must be located prior to the alarm interface (see fig.2).
Identify the incumbent telephone service line bringing the existing telephone service to the distribution device.
It is highly recommended that you disconnect the incumbent telephone service line at the demarcation point before proceeding.
Cut the incumbent telephone service line and strip the outer jacket off each end leaving the insulated wires. The wires for line one are typically red and green (occasionally blue and white/blue). The wires for line two are typically yellow and black (occasionally orange and white/orange). Check the premise distribution device to identify which wires are used for line one and line two.

Using the butt splices provided, splice the wires on the incumbent telephone service line and the wires on the switch labeled "COMPANY A" (see fig.1).
Using the butt splices provided, splice the wires from the premise distribution device and the wires on the switch labeled "PREMISE WIRING" ( see fig.1 ).
Alternative : Remove the wires from the distribution device and terminate the premise wires on the switch directly to the distribution device.
Plug the incumbent telephone service line back in at the demarcation point and set the switch to the proper position (Company B for EMTA, and Company A for incumbent). Check to see that the telephone is working properly.