Specifications

SIM900 AT Commands Set
SIM900_ATC_V1.01 137 23.06.2010
Test Command
AT+CHF=?
Response
+CHF: (0-1),(0-2)
OK
Response
OK
ERROR
If error is related to ME functionality:
+CME ERROR: <err>
Write Command
AT+CHF=<in
d>[,<state>]
Parameters
<ind> 0 Unsolicited result code disabled
1 Unsolicited result code enabled
(non-volatile)
<state> 0 main audio handset channel
1 aux audio headset channel
2 main audio handfree channel
(volatile)
Reference Note
For this command, please refer to actual model.
6.2.21 AT+CHFA Swap the Audio Channels
AT+CHFA Swap the Audio Channels
Response
+CHFA: <n>
OK
Read Command
AT+CHFA?
Parameter
See Write Command.
Response
+CHFA: (0 = NORMAL_AUDIO, 1 = HEADSET_AUDIO, 2 =
HANDFREE_AUDIO)
OK
Test Command
AT+CHFA=?
Parameter
See Write Command.
Response
OK
+CME ERROR: <err>
Write Command
AT+CHFA=<n>
Parameter
<n> 0 main audio handset channel
1 aux audio headset channel
2 main audio handfree channel