Intel MD566X - Manual (Page 37)

56K V.92 Data, Fax, and Voice Chipset
Programmer’s Guide Intel Confidential 37
the same as the test string, then the
DTE-to-modem communication channel is
working properly.
+++AT TIES Escape Sequence is used to return
to command mode.
OK Modem enters command mode.
AT&T0 Terminates any loopback test.
OK Modem aborts analog loopback and stays
in command mode.