Method and apparatus for conducting surveillance in a SS7 Intelligent Network (IN) or Advanced Intelligent Network (AIN) provides in the case of AIN that an Info Analyzed trigger is armed in an end office switch and notifies a delivery function when a call is processed. The delivery function instructs the end office switch to forward the call to the delivery function, where it is accessed for monitoring forwarded back to the end office switch. A similar method is used to process calls received by the SUS. In the case of IN, the identity of a line card assigned to a subscriber under surveillance (SUS) is changed to a number dedicated to surveillance subjects. Calls originated by the SUS are forwarded to a delivery function, which identifies the SUS based on the dedicated number of the calling party, intercepts call content, and forwards the call back to the end office switch with the called party id aid the original number and id of the SUS. The end office switch then completes the call. A similar method is used to process calls received by the SUS.