Multi-channel Bit Error Rate Testing (MCBERT) measures correctness of data received on T1/E1 lines/timeslots with stored data in a reference file. The application can work in real-time with data currently being received on T1/E1 lines/timeslots, or off-line with data stored in a file. The on-line T1/E1 testing can be done on full or fractional T1/E1 timeslots.