d15 Modem Integration and Application Developers Guide version draft 0.53 Page 115 of 181
2.1.5
AT+CHLD, Call related supplementary services
At Command
Reaction
Remark
at+chld=<mode>
Switching between the active calls
<mode>
0 Ignore the incoming call
1 Switch to second call but hangs
up the first call
2 Switches between the active calls
at+chld=?
+CHLD: (0,1,1x,2,2x)
OK.
RING
ata
OK
at+chld
+CME ERROR: operation not allowed
at+chld
NO CARRIER
at+chld=2
+CME ERROR: operation not allowed
at+chld=0
OK
at+chld=1
OK
at+chld=1
OK
RING
at+chld=1x
OK
NO CARRIER
at+chld=1
OK
NO CARRIER