User`s manual

AT Command Reference Manual
1048 4-7
S16 - General Bit Mapped Test Options Status
Indicates the test in progress status.
Default: 0
Bit 0 Local analog loopback
0 = Disabled (Default.)
1 = Enabled (&T1)
Bit 1 Not used
Bit 2 Local digital loopback
0 = Disabled (Default.)
1 = Enabled (&T3)
Bit 3 Remote digital loopback (RDL) status
0 = Modem not in RDL (Default.)
1 = RDL in progress
Bit 4 RDL requested (AT&T6)
0 = RDL not requested (Default.)
1 = RDL requested (&T6)
Bit 5 RDL with self test
0 = Disabled (Default.)
1 = Enabled (&T7)
Bit 6 Local analog loopback (LAL) with self test
0 = Disabled (Default.)
1 = Enabled (&T8)
Bit 7 Not used
S17 - Reserved
S18 - Test Timer
Sets the length of time, in seconds, that the modem conducts a test (commanded by &Tn) before returning to the command
mode. If this register value is zero, the test will not automatically terminate; the test must be terminated from the command
mode by issuing an &T0 or H command. When S18 is non-zero, the modem returns the OK message upon test termination.
Range: 0-255 seconds
Default: 0