SMPP protocol

In this page you can find information about the most widely used SMS protocol, the Short Message Peer-to-Peer Protocol (SMPP). You will get an introduction to basic SMS concepts, you will learn how SMS relates to SMPP, and you will find some documents and diagrams that will help you understand this technology better.

What is an SMS protocol?

An SMS protocol is a communication rule set, used for sending short text messages in the mobile telephone network. It is also referred to as a text message service component of a telephone, Internet, and mobile device network. It uses standard messages that are sent through the network that contain all the necessary information (including sender phone number, recipient phone number, delivery report flag, message text, etc) that let mobile devices exchange short text messages.

smpp protocol
Figure 1 - SMPP protocol

How the sms protocol is used?

The SMS protocol is utilized by software applications connected to SMS gateways when office users or automated messaging software send bulk messages to mobile phones and other devices capable of receiving SMS messages. This same protocol is also used to receive SMS messages.

Is SMS a TCP or UDP protocol?

In short SMS is a TCP protocol. To be more precise SMS refers to the Short Message Service (SMS) that is used to transfer text messages in the mobile network over TCP/IP. the protocol used to transfer SMS messages over the Internet is called SMPP protocol. It is a client server protocol that requires an SMPP server such as Ozeki SMS Gateway and an SMPP client.

Figure 2 - SMPP protocol stack

In order to transfer SMS messages through the Internet a protocol stack is set up. This protocol stack uses a TCP/IP channel. On top of this communication channel optionally a security protocol layer is added. This layer is called TLS or SSL. This security layer is responsible for the encryption and decryption of the communication. The security layer is only used if a Secure SMPP server called SMPPS server is used on the server side. In this case both the SMPP client and the SMPP server is required to communicate over TLS. Ozeki SMS gateway support SMPP protocol stacks with and without the security layer.

Over the security TLS layer SMPP is used. It is a communication channel, that is responsible for carrying text messages (SMS messages) over the Internet. SMPP is used by many SMS service providers to exchange SMS messages between each other. SMPP is also used by computer applications to send SMS messages to SMS service providers.

In 2024 another layer is needed above the he SMPP layer, because the SMPP layer does not support multipart SMS transmission. This layer is called the segmentation and reassembly layer. If an application sends a text messages longer than 160 Latin characters or 70 Unicode characters, it needs to be sent in multiple parts. This is called multipart SMS technology. Ozeki SMS gateway adds this messages segmentation layer to the SMS protocol stack so both short and long text messages can be sent reliably.

Download the SMPP protocol specification

The SMPP protocol is defined in a PDF file. The PDF contains the specifications maintained by the SMPP Forum, that acts as a standardization body for this protocol. The SMPP specification is evolving and is labelled by version numbers. The most widely used version is SMPP v3.4.

You may download the SMPP protocol from the following link:
Download SMPP Protocol Specification v3.4 (pdf)

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