GSM modem

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 page

Can I install multiple modems in Ozeki NG?

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 converters.

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 sender address.

This is not a limitation of the software. It is a limitation of the GSM technology. There 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 SMS software

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 system.

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 conflict.

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?

The Ozeki SMS software implements the following IP SMS standards: SMPP v3.3, SMPP v3.4, CIMD2, 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 invalid, 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.

Does Ozeki NG SMS Gateway handle a modem with multiple sim cards?

Ozeki NG SMS Gateway does not support multiple sim cards modem. If you want to use more than one sim cards, you should connect more GSM modems to your Ozeki NG SMS gateway. You can connect the modems through USB or RS232 ports to your system.


I can send, but I cannot receive SMS messages. What can be the problem?

It is also possible, that your Ozeki NG SMS Gateway receives the SMS messages, but you have forgotten to setup an inbound routing rule to forward an incoming message to a user or application.

Check the Inbound routing settings:
http://www.ozekisms.com/index.php?owpn=138

If my Android device supports two (2) sim cards - can I receive SMS messages on both of the SIM cards? Which of the sim cards is the one, that will send the SMS message to a mobile phone?

Ozeki Android SMPP SMS Gateway forwards every SMS messages to Ozeki NG SMS Gateway that arrives on each SIM cards. If you send out the SMS message, that SIM card will send it to the recipient which is in active state on your phone.

Q. Can I use my smart phone as a GSM modem?

No, you can not. But you can install the Ozeki Android SMPP SMS Gateway that makes it possible to connect your Android mobile phone with your Ozeki NG SMS Gateway. It allows you to send or receive SMS messages in your Ozeki NG SMS Gateway.

Can I use my micro SIM card with Sierra Wireless Fasttrack modem?

Yes, you can. You need to buy an adapter that will transform your micro sim card into a normal (mini-SIM - 2FF) sized sim card.

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