A system is provided for intercepting signals transmitted between a target served by a fiber optic network and a subscriber. A network is described having a phone switch at a central office configured to receive signals for transmission to and from a target, such as the target of a criminal investigation. A signal received at the central office is assigned to an analog circuit, and a monitoring device configured to intercept and monitor the signal is installed along the analog circuit at a location that allows the monitoring of communications without notifying the target that he is under surveillance. After the signal has been monitored, it is converted to a digital signal for transmission. A method is also provided for intercepting a signal transmitted between the target served by a fiber optic network and a subscriber, such that a monitoring device may be installed without alerting the target.