Data Sheet

SIM900 AT Commands Set
SIM900R01_ATC_V1.00 58 15.01.2010
ERROR
Parameters
<type> type of address octet in integer format;
129 Unknown type(IDSN format number)
161 National number type(IDSN format)
145 International number type(ISDN format )
177 Network specific number(ISDN format)
Reference
GSM 07.07 [13]
Note
z The ATD Command overrides this setting when a number is dialed.
3.2.14 AT+CHLD Call Hold And Multiparty
AT+CHLD Call Hold And Multiparty
Test Command
AT+CHLD=?
Response
+CHLD: (list of supported <n>s)
OK
Response
TA controls the supplementary services Call Hold, Multiparty and Explicit
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>
Write Command
AT+CHLD=[<n>
]
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 t he
o t her
(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.