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Notes
•
The
command offers a broad range of options according to the GSM specifications. However, if you
AT+CHLD
attempt to invoke an option which is not provisioned by the network, or not subscribed to, invocation of this
option will fail. The responses in these cases may vary with the network (for example "Operation not allowed",
"Operation not supported" etc.).
•
The handling of the supplementary service Call hold and Multiparty varies with the types of calls. This is
because only voice calls can be put on hold, while data or fax calls cannot. The following procedures apply:
With AT+CHLD=2 the user can simultaneously place a voice call on hold and accept another waiting voice,
data or fax call. If the waiting call is a data or fax call, it is also possible to put the voice call on hold. To switch
back from the active data or fax call to the held voice call the active call must be terminated with AT+CHLD=1.
If all active and held calls are voice calls it is possible to switch back and forth with AT+CHLD=2.
•
In conflict situations, e.g. when a waiting call comes while there are already held calls, the above procedures
apply to the waiting call only. For example, <n>=0 rejects the waiting call, but does not affect the held calls.
•
See also the
AT+CCWA
Example
^SYSSTART
at+cpin="9999"
OK
+CREG: 2
+CREG: 1,"0145","0016"
at+ccwa=1,1,1
OK
atd"1234567";
OK
+CCWA: "+491791292364",145,32,,0
at+chld=2
CONNECT 9600/RLP
hello
+++
OK
at+clcc
+CLCC: 1,0,1,0,0,"03038639268",129
+CLCC: 2,1,0,1,0,"+491791292364",145
OK
at+chld=1
OK
at+clcc
+CLCC: 1,0,0,0,0,"03038639268",129
OK
MC55_ATC_V04.00
Confidential / Released
command for details on how to display waiting calls.
Page 207 of 475
The mobile is now registered.
You activate the indication of waiting calls during
voice calls.
You make a voice call.
You receive a URC indicating a waiting data call.
You put the voice call on hold.
The data connection is set up.
With ''+++'' you go in command mode.
You interrogate the status of all established calls.
The active data call is terminated and the held voice
call becomes active.
3/17/06
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