Digicom GSM BULK User manual

GSM Bulk
User Guide
Rev. 1.0 05/2003

2
INDEX
INDEX..................................................................................................................................2
PREFACE............................................................................................................................3
1. INTRODUCTION .............................................................................................................4
1.1 TECHNICAL FEATURES............................................................................................4
1.2 WARNINGS ................................................................................................................5
2. INSTALLATION...............................................................................................................6
2.1 PIN-OUT OF GSM BULK ............................................................................................6
2.2 SIM CARD...................................................................................................................7
2.3 CONNECTION TO THE EXTERNAL ANTENNA.........................................................8
2.4 LED INDICATOR.........................................................................................................9
2.4 CONNECTOR FOR THE VOICE MANAGEMENT ....................................................10
3. FUNCTIONAL EXAMPLES...........................................................................................11
A) PIN MANAGEMENT...................................................................................................11
B) GSM BULK READY TO WORK ..................................................................................12
C) SERIAL CABLE NOT COMPLETED...........................................................................13
D) DATA TRANSFER......................................................................................................13
E) SMS MANAGEMENT (TEXT MODE )............................................................................14
4. AT COMMANDS............................................................................................................17
APPENDIX A.....................................................................................................................38

3
PREFACE
All rights reserved; no part of this publication may be reproduced, stored in a retrieval
system, or transmitted in any form or by any means, electronic, otherwise, without the prior
written permission of Digicom S.p.A. The following installation rules should be respected in
order to have the best working order of the equipment and for the user’s safety.
ENVIRONMENTAL CONDITIONS
Enviromental temperature Relative humidity
from -20 to +55°C from 20 to 80% n.c.
Rapid changes of temperature or humidity should be avoided.
This equipment, including cables, should be installed in an area free from:
•Dust, humidity, heat from direct sun light.
•Objects which irradiate heat. These could cause damage to the container or other
problems.
•Objects which produce a strong electtromagnetic field (loudspeakers, etc.)
•Liquids or chemical corrosive substances.
CLEANING THE TERMINAL
Use a clean and soft cloth. Wet the cloth with water or natural detergent if it is necessary
to remove any stains. Never use chemical products such as petrol or solvents.
VIBRATIONS OR DROPPING
Caution against vibrations and dropping.
WARNING: This is a class A product.
In a domestic environment this product may cause radio interference in which case the
user may be required to take adequate measures.
DECLARATION OF CONFORMITY
We, Digicom S.p.A. registered office at: via Volta 39 - 21010 Cardano al Campo (Varese -
Italy) declare under our sole responsability that the product:
Name: GSM Bulk Type: Modem Dual-Band EGSM 900/1800MHz
satisfies the basic requirement of the below indicated Directive:
•1999/5/CE of March 9 1999, R&TTE
as having been designed in conformity with the requirements of following Reference
Standards:
EN 60950 EN 301 489-1 EN 301 489-7 EN 301-419-1 EN 301-511

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1. INTRODUCTION
Congratulation on choosing digicom GSM Bulk.
GSM Bulk is a GSM Dual-Band modem
(EGSM900/DCS1800), perfect for DATA, SMS,
FAX and VOICE applications.
GSM Bulk can operate also in GPRS.
It has been designed to operate on any
digital GSM network both directly and in roaming.
GSM Bulk is compliant with GSM Class 4
(900Mhz) and Class 1 (1800 Mhz). The dual band
functionality depends on the network. Please refer
to GSM provider for the availability of the service.
1.1 TECHNICAL FEATURES
Power Supply
5 Vdc ±10%
Size
76x48x15mm
Weight
About 40gr
Operating Temperature
From -20°C to +55°C
Storage Temperature
From -20°C to +70°C
Data Interface
RS232 (TTL) : male connector 2x9pin lead-space 2.54
Antenna Connector
Type SMA female connector

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1.2 WARNINGS
Satefy
Read carefully these instructions and notes before powering GSM Bulk. For each situation
please follow the specific instructions.
GSM Bulk is a low power radio transmitter and receiver. When it is ON, it sends receives
radio frequency (RF) signals.
GSM Bulk produces magnetic fields. Do not place it next to magnetic support such as
floppy disks, tapes, et. . Operating your modem close to other electrical equipment such
as television, phone, radios and personal computer, may cause interference.
Interference
GSM Bulk, like all wireless devices, is subject to interferences that may reduce its
performances..
Road Safety
Do not use GSM Bulk while driving. In case of use on cars, it is necessary to check
that electronic equipment is shielded against RF signal. Do not place GSM Bulk over
the air bag or in the air bag deployment area.
Aircraft Safety
Switch off GSM Bulk in aircraft by disconnecting the Power cable. Using GSM
devices on aircraft is illegal.
Hospital Safety
Do not use GSM Bulk near health equipment, especially pacemaker and hearing
aids, to avoid potential interferences. GSM Bulk is a not mobile phone, do not use it
in direct contact with the human body. Switch it off in hospitals, and medical center.
Hospitals or health care facilities may be using equipment that could be sensitive to
external RF energy.
Explosive Materials
Do not use GSM Bulk in refuelling points, near fuel or chemicals. Do not use the
GSM Bulk where blasting is in progress. Observe restrictions, and follow any
regulation or instruction.
Instructions for use
Do not use GSM Bulk in direct contact with the human body, do not touch the
antenna if not necessary when the phone is in use. Use approved accessories and
batteries only. Do not connect incompatible products.

6
2. INSTALLATION
The GSM modem installation must be carried out between a range of temperature
indicated in the manual.
Attention: the power supply voltage must not exceed the indicated maximum
value as this may cause a damage of the product.
2.1 PIN-OUT OF GSM BULK
The following table shows the pin-out connector:
PIN
J5
PIN
J7 SIGNAL DIRECTION ELECTRIC LEVEL
1 - DCD DTE <== DCE TTL 0 = Active
2 27 DSR DTE <== DCE TTL 0 = Active
3 28 RxD DTE <== DCE TTL 0 = Space
4 30 RTS DTE ==> DCE TTL 0 = Active
5 25 TxD DTE ==> DCE TTL 0 = Space
6 13 CTS DTE <== DCE TTL 0 = Active
7 29 DTR DTE ==> DCE TTL 0 = Active
8 - RING DTE <== DCE TTL 0 = Active
9 1-2-6 Gnd - 0 Volt
10 3-4 5Vdc - 5 Volt
11 - - - N.C.
12 15 On/Off DTE ==> DCE
TTL 1 = On
TTL 0 = Off
13 - - - N.C.
14 21-24 Gnd - 0 Volt
(U4) 1 20 Mic ( + ) DTE ==> DCE
(U4) 2 - Mic ( - ) DTE ==> DCE
(U5) 1 12 Spk ( + ) DTE <== DCE
J5 : RS232 [ standard ]
(male connector 2x7pin lead-space 2.54)
U4 : Microphone input [ standard ]
(male connector 2pin lead-space 2.54)
U5 : Speaker output [ standard ]
(male connector 2pin lead-space 2.54)
J7 : RS232 [ optional ]
(male connector 2x25pin lead-space 1.27) (U5) 2 - Spk ( - ) DTE <== DCE
Power supply
Vcc =
Icc =
5Vdc ±10%
350mA typ [1700mA max]
RS232 interface: TTL levels
IN Signal:
TD, RTS, DTR, On/Off OUT Signal: RD, CTS, DSR, DCD, RI
Vih = 2,0 V min
Vil = 0,8 V max
Voh = 2,4 V min
Vol = 0,4 V max

7
In case your application supports TD and RD (transmission and reception) signals only, it
is possible to connect it to the GSM Bulk. In this case it is important to configure GSM Bulk
to ignore the not present criteria.
[For further information on commands, see the chapters “Functional Examples” and “AT
Commands”]
The modem can receive AT commands at the speeds between 300 and 115200 bit/s.
2.2 SIM CARD
Plug-in SIM are supported by GSM Bulk.
To prevent damaging or losing information avoid touching the sim gold area.
Attention: check with your GSM provider if your SIM is enabled for DATA and FAX traffic.
When you ask for these services, the GSM provider will give you two numbers (one for
DATA and the other for FAX calls)
Insert the SIM
Probably the SIM card will be supplied in a card holder
compliant with the devices using the full-size SIM.
1. Remove the SIM carefully from the SIM holder.
2. Turn off GSM Bulk, by disconnecting the power
connector.
3. Discover the SIM slot and press on the release pin with a finger or a pencil.
4. Insert the SIM card into the holder. Be sure the angled corner is top right.
5. Close the SIM holder and press it up to the end. Do not force the SIM holder and
verify the correct position.

8
2.3 CONNECTION TO THE EXTERNAL ANTENNA
To connect the external antenna go on as follows:
1. Turn off your GSM Bulk by disconnecting the power connector.
2. Connect the SMA male connector to the external antenna of GSM Bulk, screwing it
clockwise.
3. Place the antenna and check there is a good quality signal.
You can check the signal:
•Using a cellular phone
Insert the SIM of the GSM Bulk in a cellular phone and check the quality of the
signal.
•Through the Led STATUS (see: “Led Indicator” paragraph)
Power on the modem and verify the STATUS Led. If it is red blinking, it means the
modem is recognized by the GSM network. In this way you can check the signal but
not its quality.
Attention: even if you see the STATUS Led blinking, it may not be sufficient
for data transmission.
•Through the AT+CSQ command (see: “GSM Bulk ready to work” example)
By using this command it is possible to detect a more precise signal. Power on
GSM Bulk, connect it to a your application and send to the modem the command
AT+CSQ.
The modem will answer with +CSQ: x,y; where “x” is the signal quality, “y” is the
BER (Bit Error Rate).
The value of “x” can be included between 0 to 31; the higher value indicates a better
signal.
From 0 to 9 : poor
From 10 to 15 : good
From 16 to 31 : excellent
99 = Unknown or uncalculable
BER values higher than 2 may compromise the good operation of the device. In this
case place the antenna in a better position.
[ For further information on the commands, see the chapters “Functional Examples” and
“AT Commands ]
Attention: for better performances of the antenna, do not fix it directly to the
mechanics of the product or on metal surfaces.

9
2.4 LED INDICATOR
Through a led STATUS indicator you can control the status of GSM Bulk:
LED STATUS DESCRIPTION
STATUS OFF No power supply
ON GSM Bulk is in one of the following status:
- network search mode;
- SIM card not present;
- PIN not inserted;
- emergency mode.
SLOW
BLINKING GSM Bulk detected by the GSM network
FAST
BLINKING GSM Bulk connected to another device
GSM Bulk is ready to work only after it has been registered by the GSM network and with
a good quality signal.
To verify that GSM Bulk is ready for calls and SMS, follow these commands:
COMMAND DESCRIPTION
AT+CPIN? Verifies the presence of the SIM and the PIN code
AT+CREG? Verifies the registration to the GSM network
AT+COPS? Verifies the current GSM operator
AT+CSQ Verifies the quality of GSM signal
[ For further information on the commands, see the chapters “Functional Examples” and
“AT Commands” ]

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2.4 CONNECTOR FOR THE VOICE MANAGEMENT
For the voice functionality, GSM Bulk is equipped with two male connectors 2pin
lead-space 2.54
The modem includes AC coupling and biasing for electret microphone.
Suggested characteristics for the microphone
Biasing : 2V – 0.5mA
Impedance:
2KΩ
Sensitivity: from –40dBm to –50dBm
SNR (Signal to Noise Ratio): > 50dBm
Suggested characteristics for the speaker
Impedance:
150Ω
Power: 10mW
Impedance of the speaker amplifier output in differential
mode is 1Ω±10%
[ For further information on the commands, see the chapter “AT Commands” ]

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3. FUNCTIONAL EXAMPLES
GSM Bulk can be programmed through a set of AT commands for the execution of all its
functionalities.
Here the description of some applications. For the complete AT command set, see the
chapter “AT Commands”.
Attenzione: In the factory configuration the AT commands are managed at 9600 bt/s
only. Before going on with your settings, you must set your terminal emulator (eg.
HyperTerminal) or your application as follows: 9600,8,N,1 then you can modify the
interface speed with the values included between 300 and 115200bit/s with the
command AT+IPR.
A) PIN management
B) GSM Bulk ready to work
C) Serial cable not completed
D) Data transfer
E) SMS Management (Text mode)
A) PIN MANAGEMENT
Due to security reasons, usually SIM cards require the insertion of PIN code. With GSM
Bulk you can insert the PIN code through the AT+CPIN command.
If your application has other security systems, you can disable the PIN request using a
mobile phone.
Examples:
Command: AT+CPIN? (Verify the SIM and the PIN status)
Answer: ERROR (SIM card reading failed)
Answer: +CPIN: READY (PIN code present: SIM ready)
Answer: +CPIN: SIM PIN (PIN code insertion is required)
Answer: +CPIN: SIM PUK (PUK code insertion is required)
Answer: +CPIN: SIM PIN2 (PIN2 code insertion is required)
In case the PIN code is not present, it must be inserted before using the SIM card:
Command: AT+CPIN=4321 (PIN insertion)
Answer: OK (PIN code right)
Answer: ERROR (PIN code wrong)
Attention: remember that if the PIN code is wrongly inserted for three times, the SIM card
will block. To unblock it you must insert the PUK CODE.
[ For further information on the command, see the chapter “AT Commands” ]

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B) GSM BULK READY TO WORK
GSM Bulk can work only after it has been detected by the network and with a good GSM
signal. To verify GSM Bulk is ready to manage calls and SMS, follow these commands:
Command: AT+CPIN?
Answer: +CPIN: READY (SIM is ready)
Command: AT+CREG?
Answer: +CREG: 0,1 (GSM modem is registered by the network)
OK
Command: AT+COPS?
Answer: +COPS: 0,2,22288 (GSM Bulk is registered at operator 22288)
OK
Command: AT+CSQ
Answer: +CSQ: 15,0 (GSM signal: good)
OK
The CSQ value can be included between 0 and 31, where 0 = –113dBm and
31 = –51dBm.
Every unit corresponds to 2 dBm.
From 0 to 9 = not sufficient
From 10 to 15 = good
From 16 to 31 = excellent
99 = unknown or uncalculable
[ For further information on the commands, see the chapter AT Commands ]

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C) SERIAL CABLE NOT COMPLETED
In case your application (eg. PLC) supports only TD and RD signals (Trasmission and
Reception), it is however possible to connect it to the GSM Bulk. In this case you will use a
non-completed serial cable; for this reason it is important to configure GSM Bulk so that it
ignores the serial criteria not present. Usually GSM Bulk, during the communication phase,
checks the following criteria: 108 (Data Terminal Ready) and 105 (Request To Send): to
disable them use the commands AT&D and AT+IFC.
Examples:
Command: AT&D0 (Criterion 108 ignored)
Command: AT&D2 (Criterion 108 managed as per specification)
Answer: OK
Command: AT+IFC=0,0 (Criterion 105 ignored: flow control OFF)
Command: AT+IFC=2,2 (Criterion 105 managed as per specification: flow control ON)
Answer: OK
D) DATA TRANSFER
GSM Bulk can call and be called by analog (PSTN), digital (ISDN) and GSM devices.
Usually DATA connections with analog modems are at 9600bit/s (V.32 protocol); ISDN
connections use V.110 protocol with speed at 9600bit/s. The data transfer with another
GSM device is carried out using V.32 or V.110 protocols.
DATA Calls
Using the ATD command it is possible to make a call. For example, to call the number
0123456789 you must send to the modem the command ATD0123456789<Enter>.
Depending on the AT+CBST command setting it is possible to program GSM Bulk for
analog, digital or GSM calls:
AT+CBST=0,0,1 connection with analog or GSM modems in multistandard (V.32)
AT+CBST=7,0,1 connection with analog or GSM modems only in V.32 at 9600bit/s
AT+CBST=71,0,1 connection with digital or GSM modem only in V.110 at 9600bit/s
Attention: check with your telephone operator if your SIM is enabled for DATA
and eventually for FAX. In fact most SIMs are enabled for Voice (call and
reception) while for DATA and FAX only the call is enabled.
To enable the reception of DATA and FAX traffic it is necessary to ask the
telephone operator that will assign two additional numbers (one to receive
DATA calls and one to receive FAX calls).

14
Examples:
Command: AT+CBST=7,0,1 V.32 call at 9600bit/s
Answer: OK
Command: ATD0123456789
Answer: CONNECT 9600
Command: AT+CBST=71,0,1 V.110 call at 9600bit/s
Answer: OK
Command: ATD0123456789
Answer: CONNECT 9600
DATA calls reception
Generally in GSM Bulk the automatic answer is disabled (S0=0): in this case the modem
will answer only after it received the ATA command.
In case you want to enable the automatic answer, you must set the S0 register with the
number of rings after which to answer (eg. S0=2 automatic answer after two rings).
GSM Bulk factory configuration has the AT+CBST=0,0,1 setting, in this way it will be able
to answer to any call coming from an analog, ISDN or GSM modem.
[ For further information on the commands, see the chapter “AT Commands” ]
E) SMS MANAGEMENT (TEXT mode)
GSM Bulk manages the SMS in TEXT and PDU format.
Send a SMS (TEXT mode)
You find here the necessary commands to send SMS in TEXT mode.
1) Reading and Setup of the Services Center
To activate the SMS management, you must insert the identifier number of the Services
Center for your GSM operator. In the most recent SIM cards, the identifier is already
present in memory: to verify you can use a mobile phone or, with GSM Bulk, you can
act as follows:
Command: AT+CSCA? (reading of Services Center)
Answer: +CSCA: “[phone]”,145 (Services Center present)
OK
If the Services Center number is not present, ask the telephone operator, then insert the
identifier as follows:
Command: AT+CSCA=”[phone]” (eg. TIM Services Center)
Command: AT+CSAS (Save the number of Services Center)
Answer: OK

15
2) Define the mode
Command: AT+CMGF=1 (TEXT mode)
Answer: OK
Command: AT&W (Save the configuration)
Answer: OK
3) Send a message:
Command: AT+CMGS=”[phone]”<enter>
Answer: >
Text: First SMS message with GSM Bulk<ctrl z>
Answer: +CMGS: <sms index>
OK
After you digit your message, press <ctrl z> (Hex =1A).
In this example the message “First SMS message with GSM Bulk” is sent to number
[phone].
Attention: In case of error after you send the SMS, check the identifier of the Services
Center with your Telephone Operator.
Read the SMS (TEXT mode)
The factory configuration of GSM Bulk detects the coming of a new SMS. When an SMS
arrives, GSM Bulk send to the DTE (eg. PC) the following message: +CMTI: “SM”,2 (2
indicates the memory location of the SIM card where the SMS has been stored). To read
the message use the AT+CMGR command:
Command: AT+CMGR=2
Answer: +CMGL: 2,"REC UNREAD","[phone]",,"01/01/75,12:05:46+04"
Second SMS message with GSM Bulk
To display all the messages present in the SIM memory:
Command: AT+CMGL=”ALL”
Answer: +CMGL: 1,"REC READ","[phone]",,"01/01/75,12:05:46+04"
First SMS message with Pocket
+CMGL: 2,"REC UNREAD","[phone]",,"01/01/75,12:06:26+04"
Second SMS message with GSM Bulk
OK
Through the AT+CNMI command it is possible to program the GSM Bulk so as it sends
immediately the received message to the DTE (eg. PC):
Command: AT+CNMI=2,2
Answer: OK

16
With this configuration GSM Bulk sends immediately the message to the DTE, when it
receives it from the network:
+CMT: "[phone]",,"01/01/75,12:06:14+00"
First SMS message with GSM Bulk
Cancel the SMS
For example, to cancel the second message:
Command: AT+CMGD=2
Answer: OK
[ For further information on the commands, see the chapter “AT Commands” ]

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4. AT COMMANDS
GSM Bulk supports a complete AT commands set to configure and test the modem and all its
functionalities.
These commands are based on the following recommandations:
•ETSI GSM 07.07 : Digital cellular telecommunications system (Phase 2); AT command set for
GSM Mobile Equipment (ME);
•ETSI GSM 07.05 : Digital cellular telecommunications system (Phase 2); Use of DTE-DCE
interface for Short Message Service (SMS) and Cell Broadcast Service (CBS);
•ITU-T Recommandation V.25ter : Serial asynchronous automatic dialling and control.
The factory configuration of GSM Bulk accepts AT commands only at 9600bit/s. Before going on
you must set your terminal emulator (e.g. HyperTerminal) or your application with these values:
Bit per second = 9600
data bit = 8
parity = None
stop bit = 1
flow control = Hardware (RTS/CTS)
Use the commands AT+IPR, AT+ICF, AT+IFC to change the modem interface speed and the flow
control.
4.1 COMMANDS NOTES
Please read these before using GSM Bulk:
•The commands always start with AT; it means Attention, and end with <CR> (Hex=0D)
character.
•The answer messages in extended format (ATV1 command) start and end with <CR><LF>
(Hex=0D 0A). If Pocket GSM is programmed to manage numeric answers (ATV0), then the
answer will not have the prefix <CR><LF> and will be ended with the <CR> character.
•To disable the answer messages use ATQ1 command.
•If the syntax of the command is wrong, the modem sends the answer ERROR
•If the syntax of the command is correct but some incorrect parameters are used, the strings
+CME ERROR: <Err> or +CMS ERROR: <SMSErr> are sent with different error codes.
•If the command has been successfully executed, the answer will be OK.
(In some cases, such as AT+CPIN? the modem will return the information requested without
OK)
[ In the “Functional Examples”, and in the “AT commands description”, the characters <CR> and
<CR><LF> have been intentionally omitted.]

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4.2 AT COMMANDS DESCRIPTION
4.2.1 GENERAL COMMANDS
ATA Answer an incoming call
When the modem receives a call, it sets the Ring Indicator signal and sends to the DTE (e.g. PC)
the RING string (or +CRING: <type> if AT+CRC=1). If the automatic answer is disabled (ATS0=0),
the ATA command enables the answer to an incoming call.
Command Possible answers Action
ATA CONNECT
OK DATA call accepted VOICE call accepted
ATD Dial command
This command will dial the number entered after the ATD string. When the modem detects the
carrier from the GSM base station, it will answer with the message CONNECT: at this point the
data transmission starts.
For further information on ATD command, see chapter “Functional Examples”.
Command Possible answers Action
ATD<str> CONNECT
OK
BUSY
NO ANSWER
NO CARRIER
DATA / FAX connection is established
VOICE connection is established
Remote device busy
No answer from the called number
Failed or refused call
<str> Description Examples
Numbers 0...9 National call ATD0123456789
+ International call ATD+987654321
; At the end of the number for the VOICE calls ATD0123456789;
L Redial the last called telephone number ATDL
>”text” Call to the number in the phonebook associated
with the “text” indentifier
(by AT+CPBS command)
ATD>”Digicom”
>mem<idx> Call to the number contained in mem position nATD>SM2
>n Call to the number stored in the position n of the
current phonebook; it can be selected with the
AT+CPBS command
ATD>1
ATE Echo command
When the modem receives a command, it executes the echo of the received characters. With this
command it is possible to enable and disable the echo.
Command Possible answers Action
ATE0
ATE1 OK OK Echo disabled Echo enabled
Default: ATE1

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ATH Hang up
When the modem is on-line after the escape sequence “+++”, this command forces the modem to
disconnect.
Command Possible answers Action
ATH OK The modem disconnects
ATO Back to On-Line mode
If you have to interrupt the data flow temporarily to verify the modem status or some registers
without disconnecting, you can use the “+++” escape sequence. Then send the AT0 command to
return to data mode.
Command Possible answers Action
ATO CONNECT Back to On-Line mode
ATQ Answer messages
This command is used to enable and disable the modem answers.
Command Possible answers Action
ATQ0
ATQ1 OK OK Answer messages enabled Answer messages disabled
Default: ATQ0
ATS0 Auto answer
The S0 register allows to disable (ATS0=0) or to enable the modem autoanswer when arriving an
incoming call.
Command Possible answers Action
ATS0=<n>
ATS0? OK / ERROR OK Auto answer after nrings Reading of S0 register
Default: ATS0=0
ATV Result code format
This command determines the modem response format: verbose code or numeric code.
Command Possible answers Action
ATV0
ATV1 OK OK Result code display as digit Result code display as words
Default: ATV1
ATZ Load user profile
This command will load a user profile previously saved with the AT&W command.
Command Possible answers Action
ATZ OK Loads the user profile

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AT%D Automatic dialing with DTR (C108)
This command allows to activate a DATA or VOICE autocall to the number stored in the first
location of the SIM phonebook; or the automatic sending of an SMS stored in the SIM first location.
The number is dialed when DTR passes from OFF to ON status; the short message is sent when
DTR passes from OFF to ON status.
Command Possible answers Action
AT%D0
AT%D1
AT%D1;
AT%D2
OK
OK
OK
OK
Function disabled
Enables automatic dialing (DATA)
Enables automatic dialing (VOICE)
Enables automatic sending of the SMS
Default: AT%D0
AT&C Data Carrier Detect (C109)
This command defines the management of the DCD (C109) on the modem serial port. If controlled
(AT&C1), the DCD ON indicates the connection with a remote device. If forced (AT&C0) regardless
of the status (connected/disconnected), the DCD is always ON.
Note: Data Carrier Detect can be controlled in DATA and FAX modes only.
Command Possible answers Action
AT&C0
AT&C1 OK OK Data Carrier Detect always ON Data Carrier Detect is controlled and follows
the connection status
Default: AT&C1
AT&D Data Terminal Ready (C108)
This command defines the management of the DTR (C108) on the modem serial port. The DTR
comes from the DTE (e.g. PC) to the modem, for this reason the criterion can be present or
absent. If absent, the modem must be configured to ignore the criterion (AT&D0). If present, the
modem will accept the call only if the criterion is ON.
For further information on AT&D command, see chapter “Functional Examples”.
Command Possible answers Action
AT&D0
AT&D1
AT&D2
OK
OK
OK
DTR is ignored
Modem switches from data to command
mode when DTR switches from ON to OFF.
When DTR switches from ON to OFF, the
modem disconnects.
Default: AT&D2
AT&F Restore factory settings
This command is used to load the factory settings for the command listed in the table.
Command Possible answers Action
AT&F OK Loads the factory configuration
Commands restored with AT&F
Q S0 V %D +CBST +CLIP +CMEE
+CMGF +CNMI +COPS +CR +CRC +CREG +CSMP
+ECHO +ILRR +SIDET +SPEAKER +VGR +VGT