Specifications

ISU AT Command Reference Phase I AT Commands
Iridium Proprietary Version 2.45
20 June 2011 21
5.25 &Cn - DCD Option
Select how the ISU controls the DCD behavior.
0 DCD is forced on at all times.
1 DCD indicates the connection status (default).
5.26 &Dn - DTR Option (Initial implementation; revised in Phase III)
Set the ISU reaction to DTR signal.
DTR must be ON during on-hook command mode. If DTR transitions from ON to OFF during on-hook
command mode, operation will be locked after approximately 10 seconds. On-hook command mode
operation will resume when DTR is restored ON.
DTR must be ON at call connection.
DTR must be ON during both in-call command mode and in-call data mode. Reaction to DTR ON to OFF
transitions during in-call command mode and in-call data mode is determined by the &Dn setting as shown
below.
0 If DTR transitions from ON to OFF during in-call command mode, and DTR is restored ON
within approximately 10 seconds, the call will remain up. If DTR is not restored ON within
approximately 10 seconds, the call will drop to on-hook command mode.
If DTR transitions from ON to OFF during in-call data mode, the mode will remain in in-call
data mode. If DTR is restored ON within approximately 10 seconds, the call will remain up.
If DTR is not restored ON within approximately 10 seconds, the call will drop to on-hook
command mode.
1 If DTR transitions from ON to OFF during in-call command mode, and DTR is restored ON
within approximately 10 seconds, the call will remain up. If DTR is not restored ON within
approximately 10 seconds, the call will drop to on-hook command mode.
If DTR transitions from ON to OFF during in-call data mode, the mode will change to in-call
command mode. If DTR is restored ON within approximately 10 seconds, the call will
remain up. If DTR is not restored ON within approximately 10 seconds, the call will drop to
on-hook command mode.
2 If DTR transitions from ON to OFF during either in-call command mode or in-call data mode,
the call will drop to on-hook command mode (default).
3 If DTR transitions from ON to OFF during either in-call command mode or in-call data mode,
the call will drop to on-hook command mode and the ISU will reset to AT command profile 0.
5.27 &Fn - Restore Factory Settings
Recall factory defaults.
0 Recall factory default 0.
5.28 &Gn - Guard Tone
Select guard tone.
No action, compatibility only.