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Cli validity – Siemens Brodersen MC55 AT User Manual

Page 204

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MC55_ATC_V04.00

Page 204 of 475

3/17/06

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Notes

• If the active call is a CSD call, and a waiting call is received, then the ME produces a BREAK while still in

online mode, and displays
- the +CCWA URC (as above) when the ME goes back to command mode while the waiting call is still active

and can be accepted;

- or the ^SCWA URC (as above) when the ME goes back to command mode after the waiting call has

ended.

• With the AT+CHLD command, it is possible to establish a multiparty call or to set the active voice call on hold

and then accept a waiting voice call (not possible with fax and data call). See also

AT+CHLD

• Users should be aware that if call waiting is activated (

=1), the presentation of URCs needs to be

enabled, too (

=1).

Otherwise, on the one hand, a waiting caller would be kept waiting due to lack of BUSY signals, while, on the

other hand, the waiting call would not be indicated to the called party.

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

when you attempt to enable call waiting for a

for which the service is not provisioned or not sup-

ported , the setting will not take effect regardless of the response returned. The responses in these cases vary

with the network (for example "OK", "Operation not allowed", "Operation not supported" etc.). To make sure

check the current call waiting settings with

=2.

• The AT+CCWA command has been implemented with the full set of

parameters according to

GSM 07.07. For actual applicability of SS call waiting to a specific service or service group (a specific

value) please consult table A.1 of GSM 02.04

• Despite the specifications stated in GSM 02.04 call waiting is not handled uniformly among all networks:

GSM 02.04, Annex A, provides the following specification:

"The applicability of call waiting refers to the telecommunication service of the active call and not of the waiting

call. The incoming, waiting, call may be of any kind." Nevertheless, networks do differ on the actual imple-

mentation of the service. For example, the activation of call waiting for

4, "fax", causes some net-

works to send a call waiting indication if a call "of any kind" comes in during an active fax call, but others may

(with the same settings active) indicate a waiting fax call during any kind of active call. Thus, the only reliable

way to receive or prevent a call waiting indication under any circumstances and in any network, is to activate

or deactivate call waiting for all tele- and bearer services (

255).

(num)