Abstract: A method, system and apparatus for the transparent monitoring of selected telecommunications sessions in an intelligent switched telephone network is described. The method involves conditioning the network to enable the monitoring of all telecommunications sessions originating from or terminating to any selected subscriber address. The network is conditioned by the installation of monitored trunks with translation tables, linksets and routesets which route all calls to be monitored through the monitored trunk groups. After the network has been conditioned, call monitoring can be accomplished with minimal datafill changes to the translation tables of the telephone switching system that serves the subscriber address. The monitored trunk groups are preferably loop-back trunk groups, but they may be dedicated inter-office trunk groups as well. It is also possible to designate a central switching point to monitor calls for a plurality of satellite switching points.