Data Sheet

Smart Machine Smart Decision
Reference Note
Factory setting is AT+IPR=0（auto-bauding）. V.25ter
2.2.41.1 Auto-bauding
Synchronization between DTE and DCE ensure that DTE and DCE are correctly synchronized and
the baud rate used by the DTE is detected by the DCE (= ME). To allow the baud rate to be
synchronized, simply issue an "AT" string. This is necessary when you start up the module while
auto-bauding is enabled. It is recommended to wait 3 to 5 seconds before sending the first AT
character. Otherwise undefined characters might be returned.
If you want to use auto-bauding and auto-answer at the same time, you can easily enable the
DTE-DCE synchronization, when you activate auto-bauding first and then configure the
auto-answer mode.
Restrictions on auto-bauding operation
The serial interface has to be operated at 8 data bits, no parity and 1 stop bit (factory setting).
Only the strings "AT" or "at" can be detected when auto-bauding is enabled.
AT+IPR=0 setting to auto-bauding will take effect after module resets.
Unsolicited Result Codes that may be issued before the ME detects the new baud rate (by
receiving the first AT Command string) will be sent at the previously detected baud rate.The
Unsolicited Result Codes
"RDY" and so on are not indicated when you start up the ME while
auto-bauding is enabled.
It is not recommended to switch to auto-bauding from a baud rate that cannot be detected by the
auto-bauding mechanism (e.g. 300 baud). Responses to +IPR=0 and any commands on the same
line might be corrupted.
Auto-bauding and baud rate after restart
The most recently detected baud rate can not be stored when module is powered down.
2.2.42 AT+HVOIC Disconnect Voice Call Only
AT+HVOIC Disconnect Voice Call Only
Execution Response
Command Disconnect existing voice call by local TE from Command line and
AT+HVOIC
terminate call with existing PPP or CSD connection on.
OK
Parameter Saving NO_SAVE
Mode
Max Response 20s
Time
Reference Note
V.25ter
SIM800 Series_AT Command Manual_V1.05 54 2014-07-31