User Manual

GM47/GM48 INTEGRATOR’S MANUAL
296
LZT 123 7263 R1A
19.11 AT+CHLD Call Hold and Multiparty
This command allows control of the following call related services:
• a call can be temporarily disconnected from the ME but the
connection is retained by the network;
• multiparty conversation (conference calls);
• the served subscriber who has two calls (one held and the other
either active or alerting) can connect the other parties and release the
served subscriber's own connection.
Calls can be put on hold, recovered, released, added to conversation,
and transferred similarly as defined in 3GPP TS 22.030.
This is based on the GSM/UMTS supplementary services HOLD (Call
Hold; refer 3GPP TS 22.083 [5] clause 2), MPTY (MultiParty; refer
3GPP TS 22.084 [22]) and ECT (Explicit Call Transfer; refer 3GPP TS
22.091 [29]). The interaction of this command with other commands
based on other GSM/UMTS supplementary services is described in the
GSM/UMTS standards.
Note! Call Hold and MultiParty are only applicable to teleservice 11.
It is recommended (although optional) that test command returns a list
of operations which are supported. The call number required by some
operations is denoted by “x” (e.g. +CHLD: (0,0x,1,1x,2,2x,3)).
Description Command Possible Responses
Request call related
supplementary
services
AT+CHLD=<n> • +CME ERROR <err>
•OK
•ERROR
Show if the command
is supported
AT+CHLD=? •+CHLD:(listof
supported <n>s)
• +CME ERROR <err>
•OK
•ERROR
<n> Description
... Integer type; equals to numbers entered before SEND
button in GSM 02.30 [7] subclause 4.5.5.1
0 Releases all held calls or sets User Determined User Busy
(UDUB) for a waiting call
0X ReleasesaspecificcallXfromaheldmultipartycall
1 Releases all active calls (if any exist) and accepts the
other (held or waiting) call
1X Releases a specific active call X