What is a GSM modem?
A GSM modem is a wireless modem that works
with a GSM wireless network.
A GSM modem can be an external device,
or a PC Card / PCMCIA Card. Usually, an external GSM modem is connected to a
computer through a serial cable or a USB cable. A GSM modem in the form of a
PC Card / PCMCIA Card is designed for use with a laptop computer, and it should
be inserted into one of the PC Card / PCMCIA Card slots of the laptop computer.
Similarly to a GSM mobile phone, a GSM modem requires a SIM card from
a wireless carrier in order to operate.
||What GSM modem do you suggest for
using with Ozeki NG – SMS Gateway?|
We suggest you to obtain a stable industry GSM modem
in order to work properly.
You can find our officially recommended
GSM modems (and phones), as well as other usable models at:
Recommended modems and phones
||Can I install multiple modems in
Yes, you can use up to 128 modems simultaneously. You
can connect the modems through USB or RS232 ports to your system.
||Can I connect a GSM modem over IP
to the software?|
Yes, you can use IP based GSM modems or IP to serial
If you use an IP based GSM/GPRS modem or an IP to serial converter, it will come
with a driver disk. When you install the driver disk, it will create a serial
port in your system. You can configure this port to be used with your GSM
modem in the GSM Modem configuration form of Ozeki NG SMS Gateway.
||Can I change the sender phone number
if I use a GSM Modem?|
No. If you use a GSM Modem, you cannot modify the
is not a limitation of the software. It is a limitation of the GSM technology.
is no way to specify the sender address from MO (Mobile Originated) SMS messages.
If you use an IP SMS connection (SMPP, CIMD, UCP), you can manipulate the sender
address. In this case, MT (Mobile Terminated) SMS messages are created and MT
messages allow us to change the sender address.
If you send out an SMS message from a GSM modem, the telephone number associated
with the SIM card in the GSM modem will be displayed as the sender address.
||Can I send SMS messages through more
than one service providers?|
Yes, depending on your
license you can install more than one service provider connections, and you can
use these connections simultaneously for both sending and receiving messages.
Ozeki NG has an excellent routing mechanism that allows you to route
messages to the appropriate provider and to the appropriate application. You
can define outgoing routes in the application meaning your application can
select which service provider should be used to transmit the message. You can
also use the routing table of the SMS gateway.
I have only one serial (RS232) port
on my computer. How can I attach more then one GSM phone or GSM modem to the
You can add more serial ports to your system with
USB to RS232 converters.
You can increase the number of serial ports with USB to Serial port
converters. An USB to serial converter is a cable, that is available in
most electronic and computer stores. It is
also called USB to RS232 converter.
On your computer you will probably have 4 (or more) USB ports, so you can attach
at least 4 modems through these ports with the USB to RS232 cable. If you would
like to attach more modems, you can use USB hubs to add more USB ports to your
An USB to Serial (USB to RS232) converter cable comes with a driver disk. When
you install the driver, it will register a COM port in your system. Use
this COM port when you configure your modem in the Ozeki SMS Software.
||If I attach multiple modems, can they
be the same type, or do I need different models? Will there be any conflicts?
You can use the same or you can use different models. We recommend you to use
the same model. There should not be any conflict in either case.
The Ozeki SMS software communicates with the modem through a COM port. It sends
AT commands to control the modem through this port. If two modems are installed
two different COM ports are used for the communication. There will not be any
||I can send SMS messages, but I cannot
receive, what can be the problem?|
You probably use a Symbian based GSM phone, such as a new Nokia model or an
Ericsson phone. You should use a GSM
modem instead, and this problem will be resolved.
If you can send SMS messages, it means your modem is configured properly and
the Ozeki SMS software can communicate with it. The reason you cannot receive
incoming messages is because the SMS software inside your phone "eats" the
incoming messages. This is a common problem for most mobile phones that have
Symbian OS. The only thing you can do is replace your phone to a GSM modem.
I would like to send SMS and MMS
messages from my computer. To do this, can I connect the application to any
mobile phone or GSM modem and which is better if it support both?
Yes you can. Both a mobile phone and GSM modem can be connected to your
computer with a phone-to-pc data cable (or an Infrared or Bluetooth connection)
to send and receive SMS and MMS messages.
If you have a choice, a GSM modem is a better option, because it is more
reliable and will work better in long term operations. There are two main
reasons for this. The first is that it has a less sophisticated software,
that provides less room for error. The second reason is that a GSM modem does
not have a built in battery. If you use a GSM phone the built in battery will
not last for a long time if it continuously
charged. If the battery dies, the phone is likely to stop functioning.
Is your gateway fully compatible
with Huawei hardware SMSCs?
Ozeki SMS software implements the following IP SMS standards: SMPP v3.3, SMPP
UCP/EMI 4.0. If an SMSC can accept a connection using one of these standards,
the SMS gateway can communicate with it.
We do not have experience
with the Huawei hardware SMSCs, but there should not be a problem.
My modem usually works for one or
two hours without a problem, then I see timeout messages in the log. What
causes this problem?
This seems like a hardware problem to me. It is most likely the
problem is with the modem itself, but if you use an USB to RS232 converter it
can also cause the problem.
The problem happens, because the modem fails to respond to the
computer after some time. I recommend you to replace your modem to a
Wavecom Supreme 10 model. It will solve this issue.
To give you a better understanding of how the software works:
The Ozeki SMS software communicates with the attached modem non-stop.
It continuously reads the memory of the modem to find incoming messages.
If it finds an incoming messages it downloads it and deletes it from the
memory of the modem. Some modems cannot handle this continuous communication,
and after some time they freeze or fail to respond. This usually happens on
older modems, if the modem firmware has some bugs.
||When I try to submit a message, I
receive an error. What can be the reason?|
If you can sometimes send messages, other times not, it might be
possible, that your network coverage is unreliable. To overcome this issue
you can configure Ozeki NG SMS Gateway to try to resend the message. To
configure this option, please increase the retry limit, by increasing the
value of the "Max number of tries:" field in the
"Advanced" tab of the "Server preferences" form. There is a good chance, that
the message will be delivered on the second or third try.
If you are never able to submit, there could be a different reason, for example
your SIM card might not have enough money, your SMSC configuration might be
you might not have disabled the PIN code on the SIM. For a complete list of
possible reasons, please read the information on the following webpage:
SMS submit error reasons
||I can send SMS, but I cannot receive with my modem. Why?|
You proably do not use a GSM modem. You should use a modem instead of
a standard handset.
Most standard mobile handsets have an SMS software that was designed to store
and display incoming messages to the user of the handset. Often this SMS software
"eats" incoming SMS messages, and does not forward it to the PC through the
data cable. In this case the Ozeki SMS software, that runs on your PC does not
receive the incoming message.
If your phone model is based on the Symbian mobile phone operating system (most high
end Nokia and SonyEricsson devices) you will not be able to use it for incoming
SMS. Symbian phones never deliver incoming SMS messages and incoming delivery
report to the modem interface of the phone.
Our recommended phone models are listed on the following website:
Recommended GSM devices for SMS messaging.
You might note, that on this page only GSM modems are displayed. We beleive
your best option is to get an Industrial GSM modem, such as a Siemens TC65 or a
Wavecom Fastrack. These GSM modems are very stable and reliable GSM phones. They can
be used to build professional, reliable applications.
In case you decide to choose another model, try to find one that support the
GSM 7.5.0 SMS standard.