How does an SMS gateway work

What is the SMS gateway

An SMS gateway is a communication system that allows you to send and receive SMS messages from a computer, application, mobile phones or IoT devices (Figure 1). The most important feature of the SMS gateway is that it can send and receive a large amount of SMS at the same time. This is achieved by connecting the SMS gateway directly to the mobile service provider's SMSC (SMS Service Center) via the Internet. This connection is also called an IP SMS connection or SMS over IP.

ip sms gateway
Figure 1 - SMS sending over the Internet

What is SMS protocol

The SMS protocol, or Short Message Service protocol, is a communication protocol. The SMS protocol is a set of rules that define how mobile phones, modems, IoT devices, and SMS gateways communicate with each other. In the case of SMS over an IP connection, it describes the rules for communication between the SMS gateway and the SMSC. The SMS protocol is relatively simple.

The SMS protocol specifies the format of SMS messages, the procedures for sending and receiving messages, and the error handling mechanisms that are used.

Supported SMS protocols

SMS messages are typically limited to 160 characters in length, but some carriers support longer messages. SMS messages can be sent to any mobile phone in the world, regardless of the carrier. The SMS protocol is one of the most widely used communication protocols in the world. It is a simple, reliable, and secure protocol that can be used for a variety of purposes.

Ozeki SMS Gateway supports the following SMS protocols: SMS modem, SMPP, UCP, CIMD2, HTTP/HTTPS. There are unique mobile service provider protocols such as MTN that also support them.

The SMS protocol is a vital part of the mobile communications infrastructure. It allows mobile phone users to communicate with each other and with a variety of other services.

SMS Gateway Operation

SMS gateways connect to physical mobile communication devices (SMS modem, mobile phone, IoT devices) or the SMSC (Short Message Service Center) to send and receive SMS messages.

The SMS gateway connects to physical mobile communication devices or the SMSC during sending and receiving. Modern SMS gateways, like Ozeki's SMS communication system, are highly scalable and can handle many connections at the same time, with sending and receiving working in parallel. When sending a message, the SMS gateway passes it to the SMS device or SMSC, which delivers it to the recipient's phone. When receiving a text message, the SMS gateway passes it on to other applications or clients connected to the SMS gateway, which process the message or display it on the client's screen.

What does an SMS gateway do?

An SMS gateway is a software application or hardware device that enables computers and other devices to send and receive SMS messages. It acts as a bridge between the SMS network and the internet, allowing applications to communicate with mobile phones and other SMS devices.

SMS gateways perform a variety of functions, including:

Connecting to SMS applications and clients: SMS gateways connect to SMS applications, such as marketing automation platforms and customer support systems, as well as SMS clients, such as web-based interfaces and mobile apps.

Connecting to modems, IoT devices, and the SMSC: SMS gateways connect to modems, IoT devices, and the SMSC (Short Message Service Center), which is the central hub of the SMS network.

Sending and receiving SMS messages: SMS gateways receive messages from SMS applications and forward them to the SMSC, and vice versa.

Handling notification messages: SMS gateways can handle notification messages, such as two-factor authentication codes and order updates.

Putting messages into a message queue: SMS gateways can put messages from different applications into a message queue, which ensures that messages are sent in a timely and efficient manner.

Carrying out load sharing: SMS gateways can carry out load sharing, which distributes the processing of messages across multiple servers to improve performance and reliability.

Scheduling timed SMS messages: SMS gateways can schedule timed SMS messages, such as appointment reminders and marketing campaigns.

Writing a log file: SMS gateways can write a log file of their activity and events.

Handling messages with different character encodings: SMS gateways can handle messages with different character encodings, such as ASCII and Unicode.

Rewriting the sender's phone number: SMS gateways can rewrite the sender's phone number, if necessary.

Features of an SMS gateway

  • Scalability: SMS gateways can be scaled to handle large volumes of messages.
  • Reliability: SMS gateways are highly reliable, ensuring that messages are delivered on time and in full.
  • Security: SMS gateways use encryption and other security measures to protect messages from unauthorized access.
  • Flexibility: SMS gateways can be integrated with a variety of connections, applications, and systems.


SMS gateways are a critical part of modern communication, enabling businesses and organizations to reach their customers and employees via SMS. SMS gateways offer a number of advantages over other communication channels, including reliability, reach, cost-effectiveness, and flexibility.

SMS gateways are used for a wide range of purposes, including marketing, customer support, two-factor authentication, and IoT applications.

SMS gateways are essential for businesses and organizations that need to communicate with their customers and employees in a reliable, cost-effective, and flexible manner.


What makes this technology so successful?

It's simplicity and it's availability.

SMS continues to be a wildly successful communication tool across the globe. The sheer volume of daily SMS messages exchanged is staggering, making it a key revenue stream for wireless carriers. But what makes this seemingly simple technology so enduringly popular?

The answer lies in its very simplicity. All you need is a phone number and a message – it's the essence of written communication. There's arguably no easier way to send a quick text to someone. Additionally, SMS boasts near-universal compatibility, working seamlessly across all mobile networks. This widespread accessibility is a major factor in its global success.

Is this technology successful, because SMS messages can be sent and read at any time?


The near-universal presence of mobile phones makes SMS incredibly convenient. We carry these devices with us constantly, allowing us to send and receive text messages anytime, anywhere – in the office, on the bus, or even at home. Unlike phone calls, SMS offers asynchronous communication. You can send a message whenever it's convenient, and the recipient can read it at their leisure, even if they're unavailable or their phone is off. This flexibility is a major advantage. The SMS system acts as a reliable message broker, storing your text until the recipient's phone is back online or they switch it on, ensuring your message eventually reaches them.

Is the SMS technology successful, because it is more polite?


SMS offers a welcome escape from the urgency of phone calls. You can send a message without the expectation of an immediate response, allowing for more thoughtful communication. Plus, texting is the epitome of discreet communication. Unlike a ringing phone that can disrupt a meeting or a quiet environment, texts can be read silently and privately. This makes SMS perfect for situations where a phone call would be disruptive, yet you still want to stay connected. It's like having a silent conversation that fits your schedule.