Siemens AC75 - page 241

AC75 AT Command Set

9.8 AT+CHLD s

AC75_ATC_V01.002 Page 241 of 569 10/30/06

Confidential / Released

Notes

•The AT+CHLD command offers a broad range of options according to the GSM specifications. However, if you

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 command for details on how to display waiting calls.

Example

^SYSSTART

at+cpin="9999"

+CREG: 2

+CREG: 1,"0145","0016"

The mobile is now registered.

at+ccwa=1,1,1

You activate the indication of waiting calls during

voice calls.

atd"1234567";

You make a voice call.

+CCWA: "+491791292364",145,32,,0

You receive a URC indicating a waiting data call.

at+chld=2

You put the voice call on hold.

CONNECT 9600/RLP

The data connection is set up.

hello

+++

With ''+++'' you go in command mode.

at+clcc

You interrogate the status of all established calls.

+CLCC: 1,0,1,0,0,"03038639268",129

+CLCC: 2,1,0,1,0,"+491791292364",145

at+chld=1

The active data call is terminated and the held voice

call becomes active.

at+clcc

+CLCC: 1,0,0,0,0,"03038639268",129