Specifications

ISU AT Command Reference Phase VII AT Commands
Iridium Proprietary Version 2.45
20 June 2011 98
“1X” Releases a specific active call X.
“2” Places all active calls (if any exist) on hold and accepts the other (held or waiting) call.
“2X” Places all active calls on hold except call X with which communication shall be
supported.
“3” Adds a held call to the conversation.
“4” Not supported (Connects the two calls and disconnects the subscriber from both calls
(ECT)).
“4*dirno” Not supported (Redirect an incoming or a waiting call to the specified directory
number.).
“5” Not supported ($(CCBS)$: Activates the Completion of Calls to Busy Subscriber
Request.)
Test Command: +CHLD=?
Test command returns the <n> values supported by the phone. The response is in the form:
+CHLD:(list of supported <n>s)
Note: “AT+CHLD=0” can be used to set UDUB when there is an incoming call, whether or not there is a
current call active (or held), in order to support GSM 02.30 subclauses 4.4.2.3 and 4.5.5.2.
11.10 +XCSI – Extended Call State Information
This proprietary unsolicited announcement was added to allow the 9555 DTE (Application Board) to keep
track of call state during Call Hold and Multiparty operations using AT+CHLD.
Exec Command: none
Unsolicited Announcement:
+XCSI=<overall call_state>,<active call_state>,<held_call
state>,<active index>,<held index>
where:
<overall call_state>:
0 Idle (dialling possible)
1 One single-party call active
2 One multiparty call active
3 Incoming call arriving (otherwise idle)
4 One single-party call active, plus waiting call
5 One multiparty call active, plus waiting call
6 One single-party call held (dialling possible)
7 One multiparty call held (dialling possible)
8 Dual single-party call (one active, one held)
9 Dual call: single party call held, multiparty call active
10 Dual call: single party call active, multiparty call held
11 One single-party call held, plus waiting call