Siemens MC55 - page 231

MC55 AT Command Set

9.8 AT+CHLD s

obil

MC55_ATC_V01.05 Page 231 of 469 2/10/04

Confidential / Released

1X Terminate a specific call X (X= 1-7). The call may be active, held or waiting.

The remote party of the terminated call will receive a "NO CARRIER" indica-

tion. Parameter X is the call number <idx> of the targeted call in the list of cur-

rent calls available with AT command AT+CLCC.

2 Place all active calls on hold (if any) and accept "the other call" as the active

call:

• If a call is waiting, the waiting call will be accepted.

• Otherwise, if a held call is present, the held call becomes active.

2X Place all active calls except call X (X= 1-7) on hold. P arameter X is the call

number <idx> of the targeted call in the list of current calls available with AT

command AT+CLCC.

3 Add a held call to the active calls in order to set up a conference (multiparty)

call.

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 "Operat ion not allowed",

"Operation not supported" etc.).

• This Supplementary Service is only applicable to Teleservice 11 (Speech telephony), that is, voice calls can

be put on hold, while data or fax calls cannot. For example, with AT+CHLD=2 you can simultaneously place a

voice call on hold and accept another waiting voice call. But it is possible to place a voice call on hold in order

to accept a waiting data of fax call, and afterwards recover the voice call. In this case, the only difference over

speech telephony is that the data or fax call needs to be manually acc epted via ATA (see example below).

• 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 hel d 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.

RING

You now receive the RING of the data call.