SMS Gateway

What is an SMS Gateway?

It is a software that makes it possible to send and receive SMS messages to and from the mobile network.

An SMS gateway is a software that is installed to a corporate computer and gives access to an SMSCs. This software offers various interfaces for the corporate office users, IT systems and corporate applications to send and receive SMS messages automatically or manually.

For example Ozeki NG SMS Gateway is an SMS Gateway application.

How does an SMS gateway communicate with the mobile network?

An SMS gateway offers interconnection in several ways. It can connect to the mobile network over the Internet or directly through a wireless modem.

SMS messaging in the mobile network are handled by Short Message Service Centers (SMSCs). These SMSCs communicate with mobile phones through the standard GSM protocol. To connect an SMS Gateway to an SMSC you can use an SMS modem. An SMS modem is a standard mobile phone or a simplified mobile phone, that is called a GSM/GPRS modem. This mobile phone can be attach to the computer with a phone to pc data cable and it can be used to send and receive SMS messages. The advantage of this connection, that it is very easy to setup and it works on all mobile networks. The drawback is that the number of messages you can send through a wireless link is limited. On a standard GSM link, approximately 10 SMS messages can be sent per minute.

Another option is to connect an SMS gateway to an SMSC through the Internet or a private network connection (e.g.: VPN, leased line, etc). Through this connection you can send your messages to the SMSC over the Internet Protocol (IP). The problem with this approach is that SMSCs are developed by different companies and they use their own communication protocol to accept IP SMS connections. For example, Nokia SMSCs can accept IP SMS connections through a protocol called CIMD2. CMG, another SMSC vendor has implemented an SMSC protocol called UCP/EMI, yet another Logice is using SMPP. The best SMS gateway implements all major protocols and gives a hand to deal with this problem.

To setup an IP SMS connection to an SMSC, you need to connect a mobile network operator or an independent SMS service provider. They will tell you which protocol do they support and will give you an IP address (or hostname), a port number a username and a password. You can use this information when you setup the IP SMS service provider connection in your SMS Gateway.

The advantage to IP SMS Connections is that they are fast, they often allow you to send several messages per second. The disadvantage is that it is often hard to sign an agreement with mobile network operators and in general due to administration it takes a long time to setup these connection.

Who are using SMS Gateways?

Mobile network operators, SMS content providers, SMS aggregators, Corporate users and Software developers

Mobile network operators use SMS gateways to interconnect SMSCs with each other to interchange traffic. In this context an SMS gateway acts as a protocol translator for example it translates SMPP into UCP/EMI.

SMS content providers use their own SMS gateway to be able to provide SMS query based services and SMS push services. They use various API's, such as an HTTP SMS API, SQL to SMS API, PHP SMS API to create custom logic to serve content.

SMS aggregators are often called independent SMS Service providers, are providing IP SMS service to their clients. They connect to the one or more mobile networks and they resell SMS messages. These companies are using the built in SMPP server of the SMS gateway, they are interested in billing support and inbound SMS routing and outbound SMS routing.

Corporate users use an SMS gateway mainly for SMS notifications and alerting. A common application in this segment is e-mail to SMS notifications.

Software developers and solution providers use an SMS gateway to save time and software complexity. The developer of an SMS text messaging application often does not want to waste time on implementing several IP SMS protocols, and does not want to work on implementing the complex SMS encoding standards. These developers prefer to use an API, such as the C# SMS API, ASP SMS API, Delphi SMS API or a simple SMS gateway configuration, such a text file to SMS gateway configuration, or an SQL to SMS gateway configuration to send and receive SMS messages. This way they can concentrate on application logic, and can make their work more efficient.

What other functionalities are provided by an SMS gateway?

Store and forward option, SMS routing and cost control.

An SMS gateway is responsible for handling capacity differences between the input and output channels. For example if an SMS application wants to send 10000 SMS messages at once, it will store these messages in a queue and will send them as capacity on the IP SMS service provider connection or GSM modem connection becomes available. This functionality is called store and forward functionality.

SMS routing is also built into most SMS Gateway's to make sure that incoming messages and outgoing messages end up where they should. SMS routing is based on message source and matching patterns, that determine the destination for a message. For example messages containing a certain keyword can be routed to a certain application.

Cost control makes it possible to prevent certain users of the SMS gateway to send too many messages and these feature provide support for billing purposes. Cost control in SMS Gateways is handled by built in SMS traffic logging and SMS accounting systems.

Do I have to pay for SMS if I have my own SMS Gateway?


If you connect your SMS Gateway to the mobile network through a GSM or GPRS modem, you need a SIM card. The SIM card can be purchased from a mobile network operator. The SIM card will have an associated price plan, that will determine the cost of each SMS message.

If you connect your SMS Gateway to the mobile network, through an IP SMS connection, you will have to pay for each SMS message to the mobile network operator or IP SMS service provider, who has given you access (IP address, username, password) to the network.

There is no way to get around this, and send SMS free of charge. (After all if you think about it, somebody has to operate the network and it is not free to operate the network.)


My messages are not received abroad. What can cause this problem?

There are two main reasons why your message might not be reaching its recipient:

  • Incorrect Number Format: You might have used an invalid number format. For international or roaming recipients, you need to use the international number format. You can find more information about international number formats in our FAQ section on SMS number formats.
  • SMS Service Provider Restriction: It's also possible that your SMS service provider restricts sending messages to certain countries or mobile networks. To confirm this, we recommend contacting your service provider directly. Be prepared to provide details about the country and mobile network where delivery is failing.
By addressing either of these potential causes, you should be able to resolve the issue and ensure your messages reach their intended destinations.

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