I'm trying to do an analog loop back test but I get an error response to the command AT&T8.The&T8 test (and S18) commands are not used by this socket modem for the the analog loopback test.
&T Local Analog Loopback Test
The modem will perform the local analog loopback test if&T1 is selected. The test can be run only when in an asynchronous operation in non-error-correction mode (normal), e.g., AT&Q6. To terminate the test in progress, the escape sequence must be entered first.
<value>Decimal number corresponding to the selected option.
0 - Terminates test in progress. Clears S16.
1 - Initiates local analog loopback, V.54 Loop 3. Sets S16 bit 0. If a connection exists when this command is issued, the modem hangs up. The CONNECT XXXX message is displayed upon the start of the test.