AT Command Set
MC35_ATC_01_V05.00 Page 83 of 256 15.07.2002
Test command
AT+CGSN=?
Response
OK
Execute command
AT+CGSN
Response
TA returns identification text for determination of the individual M E.
<sn> OK
Parameter
<sn> IMEI of the t elephone (International Mobile station Equipment Identity)
Reference
GSM 07.07
Note
See also ”AT+GSN Request TA serial number identification”.
Test command
AT+CHLD=?
Response
+CHLD: (list of supported <n>s)
OK
Execute command
AT+CHLD=[<n>]
Response
TA controls the supplementary services Call Hold, MultiParty and Expl icit Call
Transfer. Calls can be put on hold, recovered, released, added t o conversation
and transferred.
OK
If error is related to ME functionality:
+CME ERROR: <err>
Parameter
<n> 0 Terminate all held calls; or set UDUB (User Determined User
Busy) for a waiting call, i.e. reject the waiting call.
1 Terminate all active calls (if any) and accept the other call
(waiting call or held call)
1X Terminate the active call X (X= 1-7)
2 Place all active calls on hold (if any) and accept the other call
(waiting call or held call) as the active call
2X Place all active calls except call X (X= 1-7) on hold
3 Add the held call to the active calls
Reference
GSM 07.07
Note
· This supplementary service is only applicable to teleservice 1 1 (Speech te-
lephony). It is neither possible to put a data or fax call on hold, nor t o switch
from a voice call to a waiting data or fax call.
The classes of waiting calls can be easily distinguished if the URC + CCWA:
<number>,<type>,<class>,,<CLI validity> is enabled. See AT +CCWA in
Chapter 4.9.
· The AT+CHLD command offers a broad range of options according to the
GSM specifications. However, many of these options are dependent on the
SIM card / service provider.
· In conflicting situations, e.g. when a waiting call comes while there are already
held calls, the above procedures apply to the waiting call only. For exam ple,
<n>=0 rejects the waiting call, but does not affect the held calls.