Technical information

Call Control
3-26 AT Commands Reference Manual January 31, 2007
Note: Only voice calls can be put on HOLD.
A precondition for the multi-party service is that the G24 is in control of one active call
and one call on hold. In this situation, the G24 can request the network to begin the MTPY
(Multi Party) service. Once a MTPY call is active, remote parties may be added,
disconnected or separated (removed from the MTPY call, but remain connected to the
served mobile subscriber).The maximum number of remote parties is 5.
In this command, the term CALL refers to a single or MTPY call.
A single Active call is considered a MTPY call with one call index numbered as 1.
The following table shows the +CHLD parameters.
Command Response/Action
+CHLD=<n> If the call is terminated:
OK (approve request was submitted)
NO CARRIER
If the call state is changed (link, split, from active to hold, and so on):
OK (approve request was done)
If the call is terminated and another call is answered:
OK (approve request was submitted)
NO CARRIER
OK (call answered and is now connected)
Command
Type
Syntax Response/Action Remarks
Test
+CHLD=? +CHLD: (list of supported <n>s)
OK
The Test command returns <n> values
supported by the G24 to the terminal
Table 3-10: +CHLD Parameters
<Parameter> Description
<n> Call hold operation:
0 - Releases all held calls
OR
Sets User Determined User Busy for a waiting call
1 - Releases all active calls and accepts the held or waiting call
1x - Release specific call x, where x is the serial number of a call participating in an
active MTPY call.
2 - Places all active calls on hold and accepts the held or waiting call
2x - In the case of an active MTPY call, places all active calls on hold, except for call
x. Call x remains active.
3 - Adds a held call to the conversation - MTPY
Note: "Held calls" or "active calls" means a held or active single or MTPY call. There
cannot be two or more different held/active single/MTPY calls.