| • Up to 4 independent T3 or E3 ports configurable as either all T3 or all E3 only • Full-duplex connectivity at T3 rate (44.736 MHz) or E3 rate (34.368 MHz) • Subrate and scrambling support of Quick Eagle Networks (formerly Digital Link), Larscom, ADC Kentrox, Adtran, and Verilink DSUs • Internal or network clock selectable per channel • Line and payload loopback capabilities: – Local and remote loopback at the T3 level – Response to embedded loopback commands – Insertion of loopback commands into transmitted signal Bit-error-rate-testing (BERT) pattern generation and detection per channel – Selectable pseudorandom pattern up to 32 bits long, including all 0’s, all 1’s, 215, 220, 220 QuasiRandom Signal Sequence (QRSS), 223, alternating 0’s and 1’s – 32-bit error-count and bit-count registers – Fully independent transmit and receive sections – Detection of test patterns with bit error rates up to 10-2 • 24-hour history maintained for error statistics and failure counts, at 15-minute intervals • 16- and 32-bit cyclic redundancy check (CRC); 16-bit default | 
