Abstract: A portable self-contained T-carrier network simulating device including multiple modules which are removably mounted and connected and include a first customer premise simulation which includes an actual network smart jack and a repeater, a first T-carrier link simulation which provides conductive isolation between the ends thereof, bipolar violation removal and signal level change control to simulate a fiber link, a switching office simulation including an actual network digital signal cross-connect frame (DSX) and repeater, a second T-carrier link simulation which comprises wire T-carrier link simulation including an actual manhole repeater and line reversal device and also includes a simulation of bridge tap which is accessible from the front panel to simulate variation in the effect of positioning of the bridge tap, and a second customer premise simulation which includes an actual network smart jack and CPE jack.