The 5500-805 G.703 8448 kbps Interface Module Plug-In enables the 5500A Telecommunications Analyzer to test data communication systems operating at G. 703 8448 kbps rates in accordance with the CCITT G.703 Recommendation. The module provides the capability to transmit and receive data at the 8448 kbps rate, in either HDB3 or AMI line code formats, utilizing bipolar transmission. The mechanical interface between the module and the system under test consists of; BNC type connectors for transmit and receive data, each with a separate grounding lug that permits the user to terminate the coaxial shield if desired; and a 15-pin subminiature D-type connector for transmit and receive data (used by some modem manufacturers) whose pins are in parallel with the transmit and receive BNC connectors.