What is SMPP

The Short Message Peer-to-Peer (SMPP) protocol is an open, industry-standard communication protocol designed to provide a flexible interface for transferring short message data between a Message Center (such as a Short Message Service Center (SMSC), GSM Unstructured Supplementary Services Data (USSD) Server, or other types of message centers) and SMS application systems like WAP Proxy Servers, Email Gateways, or other Messaging Gateways. SMPP uses the client-server model of operation, despite "peer-to-peer" in the name.

External Short Message Entities (ESMEs) are non-mobile entities that communicate with an SMSC to send or receive messages. An ESME is a type of Short Message Entity (SME) that operates outside the mobile network. It can establish an application layer connection with an SMSC over a TCP/IP or X.25 network.  The connection is often made over the Internet and can use SMPP over TLS or a VPN to secure the connection. SMPP has been assigned TCP port 2775 by IANA, although other port numbers are often used as well. Once connected, the ESME can send and receive short messages to and from the SMSC, as well as query, cancel, or replace previously submitted messages using SMPP.

Network technologies that are supported:

SMPP Release v3.4 ensures compatibility and wide applicability by supporting a range of Digital Cellular Network technologies. The supported technologies include:

• GSM (Global System for Mobile Communications)
• IS-95 (CDMA - Code Division Multiple Access)
• ANSI-136 (TDMA - Time Division Multiple Access)
• iDEN (Integrated Digital Enhanced Network)

Where SMPP is Used?

SMPP is widely used across various industries due to its scalability and reliability. It is extensively employed for:

• Voicemail Alerts: Enables SMS notifications for new voice messages, originating from Voice Processing Systems (VPS), to inform customers promptly.
• Information Services: Allows mobile subscribers to request information such as currency rates, share prices, and weather updates and receive results via SMS.
• Booking Confirmations: Used by hotels, restaurants, and taxis to send instant SMS confirmations, providing more immediate notifications than email.
• Two-Factor Authentication (2FA) & OTP: Facilitates the secure transmission of One-Time Passwords (OTPs) to verify user identities during logins and transactions.

SMPP’s versatility makes it suitable for a wide range of other applications, including marketing campaigns, emergency alerts, and telemetry services.

How SMPP Works?

The SMPP protocol is based on the exchange of request and response Protocol Data Units (PDUs) between the ESME and the SMSC over an underlying TCP/IP or X.25 network. SMPP defines a data structure and a set of operations for exchanging short messages, specifying how an ESME application should interact with an SMSC. Each SMPP operation consists of a request PDU and a corresponding response PDU, with the exception of the alert_notification PDU, which does not require a response.

SMPP offers a comprehensive suite of two-way messaging capabilities, including the ability to send messages to single or multiple destinations, receive messages from other SMEs, query the status of short messages, and cancel or replace stored messages on the SMSC. Additionally, SMPP supports scheduling message delivery, setting delivery priorities, defining data coding types, and associating service types with messages.