14-2 CHAPTER 14: TESTING THE CONNECTIONTesting the BusinessModem usingAT&TnTo perform digital loopback and remote digital loopback testing use theAT&Tn command. You can type in your own data during testing or usethe modem's internal test pattern and error detector. See the followingsections for more detailed information about each AT&Tn command.Example: Sending AT&T5 will deny any requests from remote devices fora remote digital loopback test of your Business Modem.Disable error control (using the &M0 command, see Appendix B,Alphabetic Command Summary) before testing. If the modem isdetecting errors and retransmitting the affected data, your results will beinvalid.For your modem to CommandEnd testing AT&T0Enter analog loopback (AL) mode and send a CONNECTmessage. Data is shown on your screen.AT&T1Enter analog loopback mode and send a CONNECTmessage. The Business Modem sends a internal testpattern to the transmitter and loops the pattern back tothe receiver. No data is seen on your screen.AT&T2Start local digital loopback testing AT&T3Grant a remote digital loopback test of your BusinessModemAT&T4Deny a remote digital loopback test of your BusinessModemAT&T5Start local digital loopback testing AT&T6Start remote digital loopback with self-test and errordetectionAT&T7
