User Guide

AT Command Set
MC35_ATC_01_V05.00 Page 83 of 256 15.07.2002
4.15 AT+CGSN Request product serial number identification (IMEI) identical
to GSN
Test command
AT+CGSN=?
Response
OK
Execute command
AT+CGSN
Response
TA returns identification text for determination of the individual ME.
<sn> OK
Parameter
<sn> IMEI of the telephone (International Mobile station Equipment Identity)
Reference
GSM 07.07
Note
See also ”AT+GSN Request TA serial number identification”.
4.16 AT+CHLD Call hold and multiparty
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 Explicit Call
Transfer. Calls can be put on hold, recovered, released, added to 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 11 (Speech te-
lephony). It is neither possible to put a data or fax call on hold, nor to 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 example,
<n>=0 rejects the waiting call, but does not affect the held calls.