Specifications

SIM900 AT Command Manual
SIM900_AT Command Manual_V1.03 57 12/24/2010
Call Transfer. Calls can be put on hold, recovered, released, added to
conversation, and transferred.
Note These supplementary services are only applicable to tele service 11
(Speech: Telephony).
OK
If error is related to ME functionality:
+CME ERROR: <err>
Parameter
<n> 0 Releases all held calls or sets User Determined User Busy
(UDUB) for a waiting call
1 Releases all active calls (if any exist) and accepts the other
(held or waiting) call.
1x Releases a specific active call x
2 Place all active calls on hold (if any) and accept the other
(held or waiting) call.
2x Places all active calls on hold except call X with which
communication shall be supported.
3 Adds a held call to the conversation.
4 Connects the two calls and disconnects the subscriber from
both calls(ECT)
6 Swap operation(retrieves the held call and holds the active
call). Not applicable for calls engaged in a multiparty
operation(+CME ERROR returned)
6x Retrieves the specified held call x. Not applicable for calls
engaged in a multiparty operation (+CME ERROR
returned)
7x Holds the specified active call x. Not applicable for calls
engaged in a multiparty operation (+CME ERROR
returned)
8x Releases the specified call x (whatever its state).
9x Aborts MO speech call x setup without releasing other
calls. Possible if OK result code is sent before call is
connected: allowed if *PSCSSC mode = enabled and
+COLP = disabled.
Reference Note
3.2.15 AT+CIMI Request International Mobile Subscriber Identity
AT+CIMI Request International Mobile Subscriber Identity
Test Command
AT+CIMI=?
Response
OK