GSM Modem Connectivity
In this chapter you can learn how to install and
configure GSM modem connectivity for SMS messaging using the Ozeki NG -
SMS Gateway software.
If you plan to send and receive fewer than 15 000 SMS
messages per day, you can use a suitable GSM device (phone or modem)
attached to your computer with a phone-to-PC data cable. For information
about suitable phones, check out the
Supported Phones page.
The GSM device has to be equipped with a SIM card that charges (preferably)
low rates for SMS messages.
With this setup you can use a computer program such as Ozeki
NG - SMS Gateway to send and receive SMS messages. In this case, the software
uses the attached device to communicate with the GSM network.
If a message is sent out by the gateway running on the computer, it is
first sent to the attached GSM device. Then the GSM device
transmits it to the SMS Center (SMSC) of the GSM service provider,
using a wireless link (Figure 1).
Figure 1 - GSM modem connectivity for SMS messaging
When a message is received, the GSM device
stores the message in its memory or on the SIM card, and sends
a notification to Ozeki NG - SMS Gateway. When the program receives
this notification, it retrieves (reads) the message from the respective
memory cell, and then deletes the message from the device to make room
for the next incoming message.
The advantage of using a cellular modem is that you do
not need Internet connection for SMS messaging. Sending an SMS message
using a cellphone takes about 5-6 seconds. Receiving takes about the
same time. Good software, such as Ozeki NG - SMS Gateway allows you to
attach more than one device to your PC and to use them simultaneously
to increase capacity.
The best option to connect a phone to the PC is to use
a standard RS232 serial cable. To find out more about it, check out
the RS232 Serial Cable and
Industrial Modems page. USB cables, InfraRed and BlueTooth connections
are not as reliable. For information about attaching the GSM device with
a USB cable, visit the
USB Cable page.
Configuration of the GSM modem connectivity
When you have installed a GSM modem driver on your computer,
you can start to install and configure the GSM modem connectivity.
You can install and configure this connection using the
graphical user interface of
Ozeki NG - SMS Gateway. To start the installation,
click the Add button
in the top right-hand corner of the Service providers panel on the left
of the Management Console interface. (To find out how to open this
interface, check out
the QuickStart Guide.)
You can also add a service provider connection by clicking
the Add service provider item in the Service providers menu.
(To find out more about the menu,
visit the Menu page.)
After you have clicked one of these, the Add service
provider panel will show up on the right of the interface. The panel
contains a list of protocols you can install and use for communication with
an SMS service provider.
To select the GSM Modem protocol, click the Install
link in the respective entry in the list (Figure 2).
Figure 2 - Starting to install the GSM Modem connection
When you have installed the GSM Modem protocol,
the Configuration panel will show up on the right of the interface.
The first tab of the panel is the
Device settings tab, which consists of a Connection and an
Identification section (Figure 3).
Figure 3 - The Device settings tab
In the Modem or Port dropdown menu in
the Connection section, select your GSM modem or the COM port
your device is attached to.
In the SMS center edit box, specify the phone
number of the SMS center of the GSM service provider you connect to.
This address is provided by your GSM service provider. Some SMSC addresses
are listed in this documentation. If you do not know the service center
address of your GSM service provider, you can check out
In the Identification section, specify the
telephone number assigned to this connection (the phone number of your
GSM device) and the service provider name in the respective edit boxes.
Note that the phone number to be specified in the Telephone
number edit box is a mandatory value. If you leave the edit box blank,
the sending will be unsuccessful. Please also note that telephone numbers
need to be provided in international format.
To facilitate identification and to avoid confusion, you should
name the connection after the GSM service provider. E.g., if you have set up
a GSM Modem connection with Vodafone, it is advisable to name it "Vodafone".
Also, note that different connections should be given different names.
If you have different connections from the same service provider, you
can use different but similar names for them,
e.g.: "Vodafone1", "Vodafone2" (or something of the like). However, some load
balancing solutions require an identical name for different connections.
For details, visit the Load Balancing
and the Load Balancing for SMPP v3.3
After you have selected a modem or port on "Device settings"
tab, you can configure MMS settings if you wish to send MMS messages. Click
on MMS settings tab. Select "Service provider selection" tab to select a
service provider (Figure 4). If you cannot find your mobile network operator
in the list, you should specify the MMS settings manually
in the "Custom settings" tab (specify "GPRS APN", "MMSC URL", and the gateway
to send MMS messages). Finally, on "Network settings" tab you can specify the
GPRS connection settings.
Figure 4 - Service provider selection tab on "MMS settings" tab
To configure logging, click on Logging tab in
The tab has a Logging and a Log file settings section.
Here, you can choose whether to make the program write log entries about
sent and received messages in human readable format and/or log low level
communication. Choosing the latter option will make the program produce
logfiles containing binary codes representing the communication data.
You should check at least the Log sent and received messages in
human readable format checkbox, as logfiles can be useful in debugging
communication problems (Figure 5).
Figure 5 - Logging options
In the Log file settings section of the tab, you can
make specifications for the size and the number of available logfiles.
Log rotation saves disk space, as it ensures that older (and probably no
longer needed) logfiles will be automatically deleted from the log directory,
which is specified in the Log directory text box. By default, the access
path to the logfiles is: C:\Program Files\Ozeki\OzekiNG - SMS Gateway\Logs
In the Maximum log file size text box you can specify
the maximum size of a logfile. Once this size is reached, a new logfile will
be created. Specify the number of kilobytes for the size of a logfile by
entering a positive whole number. By default, the maximum logfile size is
In the Number of rotated files text box, specify
the maximum number of rotated logfiles that are saved. Specify this number
by entering a positive whole number. By default, the number of logfiles that
are saved is 4 (see Figure 5 above).
If you are content with the default specifications, leave
the text boxes unchanged.
In the Port settings tab, you can modify the GSM modem
initialization and specify the timeout handling commands.
In the Submit timeout edit box you can specify the maximum waiting time
for an SMS Center response confirming that your message has been
successfully submitted. Successful submission means that the SMS Center
has accepted the message for delivery. You can specify the waiting time
by giving the number of seconds in numerical characters representing any
positive whole number. If you are content with the default specification
(30 seconds), leave this edit box unchanged.
You can choose how to consider a message you have sent if there is no
response from the SMS Center after the specified length of time. Select
one of the three radio buttons. Select Sent to consider a message
sent even if there is no response from the SMS Center. Select Not sent
to consider a message not sent if there is no response from the SMS
Then you can enable the following options: Slow down modem communication,
Delay between sending messages (you can specify the exact time),
Disconnect and reconnect in case of timeout (Figure 6).
Figure 6 - The Port settings tab
In the Message handling tab, you can make settings
related to retrieving incoming messages and sending outgoing messages
Figure 7 - The Message handling tab
In Incoming messages section you can enable two check
boxes: Use this connection for receiving messages and Automatically
download MMS messages.
In the Method to use to read incoming SMS dropdown menu,
you can select which method to use to read incoming messages:
CMT, CMGL or CMGR.
Use the CMT method to make the GSM device send a notification about
Use the CMGL method to request the list of incoming messages.
Use the CMGR method to read the content of memory cells one at a time.
The latest standard is CMT.
In Outgoing messages section you can enable or
disable the following options: enable Use this connection for sending
to be able to send out messages; and Request delivery report SMS
if you wish to receive delivery reports via SMS about the status of your
sent messages. Include Service Center (SCA) in PDU and Do not use
PDU mode (leave unchecked if unsure): SMS messages can be received in
two ways: by text mode and by protocol description unit (PDU) mode. If PDU
mode is used, any encoding can be implemented. If you check Do not send
messages to my own phone number you can prevent the program from sending
SMS messages to yourself, i.e. to the phone number of your SIM card. You can
also check Use GPRS if available to send messages option as it
ensures much higher speed.
After you have checked the boxes you wish to use, specify SMS command
to use. You can select CMGS or CMGT. Then select ATDT
or AT+CUSD options for USSD command to use.
The Configuration panel for service provider connections
contains a Connect automatically on startup checkbox (in the bottom
left-hand corner). If it is checked, Ozeki NG - SMS Gateway will automatically
initiate a connection with the SMS Center when the program has started.
If this checkbox is not checked, the connection has to be initiated manually.
In Charset tab you can specify the characterset
handling policy. To Preferred character set you can select UCS2
or GSM7bit. SMS messages can use the GSM 7 bit character set and
the UCS2 character set. The GSM 7 bit character set can be used to send Latin
characters, the UCS2 character set can be used to send international (Arabic,
Chinese, etc.) characters.
In Charset set selection policy line you can select one of the
Best match: Convert to preferred character set if lossless
conversion is possible. (Character substitutions are not allowed.)
Transform: Convert to preferred character set if possible.
(Character substitutions are allowed.)
Enforce: Always use the preferred charset.
(Character substitutions and character losses are allowed.) (Figure 8).
Figure 8 - Charset tab
You can connect a service provider connection by
clicking the green play button beside its name in the panel of
installed service provider connections (Figure 9). To disconnect
a service provider connection, click the red disconnect button
next to the green button.
Figure 9 - Connecting the service provider connection
You can also initiate the connection manually by
clicking the Connect link in the panel of the service provider
connection (Figure 10).
Figure 10 - Links to operations
You can open the panel of a service provider connection
by clicking the name of the service provider connection in the Service
providers panel in the Management Console.
The panel of a service provider connection consists
of three sections.
In the upper section you can find the name of the service provider
connection (with the name of its protocol in brackets).
You can see an icon showing if the service provider connection
is connected. If it is not, the icon is marked with an "x".
To the right of the icon you can find links to perform
Configure: to configure or modify the configuration
of an installed service provider connection. Clicking this link will
take you back to the Configuration panel.
Events: to view the logging of the latest server events
related to the service provider connection. Clicking it will bring up
the Events panel containing the logging of the latest server events.
Connect: to connect the service provider connection with the
Disconnect: to disconnect the service provider connection
from the SMS Center.
Uninstall: to uninstall the service provider connection.
In the middle section of the panel you can see some of
the most important configuration information.
The options that have been (re)activated
during the configuration are marked with a tick.
The options that have not been
activated or those that have been deactivated during the
configuration are marked with an "x".
In the lower section of the panel of the service
provider connection you can read some information about its protocol.
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