GSM modem based wireless links vs IP SMS connections to the mobile network

In this guide you can read about how you can connect your system to the mobile network and which connection method will best suite your needs. You will read about Internet based SMS connections and GSM modem/GSM phone based (wireless) connections. It is strongly recommended to read this article, because it will help you design a well working system.


In general, when you make a decision whether you want to use an Internet SMS connection or a GSM modem the first and most important thing to check is the volume of SMS messages you expect to be sent or received in the system. If you will send or receive less then 12000 SMS messages per day a GSM modem will probably be a good option. If you will send or receive more, you should consider to use some kind of Internet SMS connection.

SMS messaging with a GSM modem/GSM phone

If you wish to connect your system to the mobile network wirelessly, you need a GSM modem or GSM phone, that you can attach to your computer with a data cable. In this case your Ozeki NG SMS Gateway software will operate this phone and will send and receive SMS messages wirelessly. To setup this connection method, you need the following components:

Figure 1 - Prerequisites for Ozeki NG SMS Gateway GSM modem connection

Your checklist (for GSM modem connection):


SIM Card - You can get this from your local mobile network operator.*

Modem - Use a Wavecom, Siemens or Multitech modem.

Data cable - Comes with the modem

Computer - Recommended: Intel P4 3Ghz, 2GB RAM, 500MB HDD, Windows OS

Ozeki NG SMS Gateway - Download it from

*The SIM card will come with a plan, that will determine how much money you will spend on each SMS.

Once you have all the prerequisites, you need to put the SIM card into the phone or modem and you need to attach it to your computer's serial port with a data cable. If your computer does not have a serial port you can use an USB data cable or a USB to RS232 converter. The quick start guide gives you the steps to setup a GSM modem/GSM phone connection, or you can watch the following video: How to send SMS using a GSM modem from a computer.

GSM modem vs GSM phone

When you setup a wireless connection, it is recommended to use a dedicated GSM modem instead of a standard GSM handset. The reason for this is that standard mobile handsets tend to be unreliable. They have a battery, that is likely to fail over time, and their software might not be very stable due to short development cycles. Although standard handsets can be used for sending messages, there is a good chance, that their built in SMS client software will "eat" incoming delivery reports and incoming SMS and MMS messages, and these messages will never make it to the PC through the data cable.

GSM modems are designed for long term use. They have simple, very reliable software that makes SMS and MMS sending and receiving possible. They also have an external antenna giving better signal strength and an external power supply that is not likely to fail.

Advantages of using a GSM modem/GSM phone connection over Internet connections:

  1. If you use a wireless connection to the mobile network through a GSM modem, Internet outages will not stop your system from sending or receiving messages. A wireless connection to the mobile network will work even if a network cable is torn by an excavator at some construction site.
  2. GSM modem based SMS systems are cost efficient. It is very easy to find a price plan, whith low or zero cost SMS tariffs when you purchase a SIM card.
  3. Wireless SMS systems can be setup in a very short time. You can attach almost any mobile phone to your computer with a datacable and you can start sending SMS messages in minutes. Although almost any mobile phone will work, a reliable GSM modem is preferred to have a reliable system.

Disadvantages of using a GSM modem/GSM phone connection:

  1. A single GSM modem can serve up to 12000 SMS messages per day. You can double or triple this number by adding a second or third modem, but this SMS volume still might not be sufficient for every system.
  2. A wireless connection can also fail. For example on new years eve, when everybody is sending new year's greeting SMS to each other the GSM networks might fail to accept messages from mobile devices.
  3. The mobile phone subscription on the SIM card might run out of money. If you use a prepaid SIM card, you will not be able to send SMS messages until you top up your balance.
  4. Only a fix sender address can be used. When you send out an SMS messages the phone number of your SIM card will be the sender address of your messages.

SMS communication through the Internet (IP SMS)

Internet based SMS connections are also called as IP SMS connections. These connections use a TCP/IP link to connect to the Short Message Service Center (SMSC) of a mobile network or an SMS service provider. On this TCP/IP link an upper layer protocol is used to send and receive the messages. In order to setup this solution you need the following prerequisites:

Figure 2 - Prerequisites for Ozeki NG SMS Gateway IP SMS connection

In this case you need to find an SMS service provider who can reach the mobile phones in your area. This SMS service provider should be able to provide SMS service through the Internet. To find such a provider, you can check our website where we list some of them: SMPP SMS Service providers. Once you have found such a provider, you need to sign up for their service to get the connection parameters. You can use these parameters to configure your Ozeki NG SMS Gateway software.

When you select an operator the most important thing is to select one that supports an official SMS protocol. There are 3 official SMS protocols: SMPP, UCP, CIMD2. All of these protocols were designed to serve SMS communication needs. They are asynchronous, high speed, and provide all the functionality SMS communication requires. Some providers will offer SMS service over HTTP. HTTP was designed to serve webpages not SMS. It adds a lot of overhead to SMS communication and is not nearly as fast and efficient as the official SMS protocols. If you sign up for an HTTP SMS service, there is a good chance, that your system will not receive incoming messages and will not be able to handle SMS delivery reports.

The most popular IP SMS protocol is SMPP. Check out the following link on how to configure an SMPP SMS service in Ozeki NG SMS Gateway:

Although not as popular, the UCP (often referred to as UCP/EMI) and CIMD2 will work just as well. The following pages give you setup instructions for these protocols:

If your only option is HTTP, check out this guide to get instructions on how to setup an HTTP SMS Service provider connection:

Advantages of Internet based SMS service provider connections:

  1. High speed. Internet SMS connections can serve up to 500 SMS messages per second
  2. No physical device is needed.
  3. Problems with wireless links, such as low GSM signal strength will not effect your system
  4. Flexible sender address assignment is possible. When you send out an SMS messages you can freely specify the sender phone number.

Disadvantages of Internet based SMS service provider connections:

  1. Can be time-consuming finding the appropriate person and signing a contract with a large mobile network operator to allow your system to connect to their Short Message Service Center (SMSC)
  2. Can be expensive. SMS Service providers often require you a monthly fee or a minimum monthly SMS volume.
  3. Takes more time to setup. Often firewalls need to be opened and parameters need to be negotiated with the SMS service providers.

Switching from GSM modem to IP SMS connection

Our customers often start with a GSM modem connection and a lower capacity software license first and they switch over to IP SMS connection and a higher capacity license when the SMS traffic on their system increases. This switch can be made seamlessly and it does not require any real change. All is needed is a small configuration change in Ozeki NG SMS Gateway: The new IP SMS connection should be configured and SMS traffic should be routed to it from the old GSM modem connection.

Building a fail-safe system

If possible it is best to have both a wireless and an IP SMS connection at the same time and Ozeki NG SMS Gateway should be configured to use the IP SMS connection when available, and if the IP SMS connection fails for whatever reason, the software should switch over to the wireless connection automatically to keep the SMS communication working. This automatic failover switching can be setup by installing two service provider connections and by configuring a backup route in Ozeki NG SMS Gateway.


Is the SMS technology successful, because it can be used by wireless applications?


The success of SMS technology can be attributed to several factors:

  1. Wide Adoption and Compatibility: SMS messaging is supported by all GSM mobile phones, making it a universal platform. This broad compatibility ensures that SMS can reach a vast user base across different devices and networks. You can exchange SMS messages not only with users on the same wireless carrier but also with users of many other carriers worldwide.
  2. Versatility for Wireless Applications: SMS serves as an excellent platform for exchanging information between applications installed on mobile phones. Building wireless applications on top of SMS technology maximizes the potential user base. SMS messages can carry not only text but also binary data (e.g., ringtones, pictures, logos, wallpapers, animations, VCards, and calendar entries).
  3. Billing Support: SMS has native support for billing. Mobile carriers offer reverse billing, allowing convenient payment options. This feature facilitates the development of mobile content delivery platforms.

To sum it up

Whatever your needs are, it is worth to spend some time on picking the appropriate connection method. In all cases Ozeki NG SMS Gateway will be a good choice to manage the connection. If you have Ozeki NG SMS Gateway installed you can check the "Add service provider" link on the Management console to find out more information.

If you don't have Ozeki NG SMS Gateway installed, I recommend you to proceed to the download page:

Download Ozeki NG SMS Gateway!

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