A2P SMSC

An A2P (Application to Person) SMSC (Short Message Service Center) is a customized network function that is specially deployed for the SMS text messages sent from a software application to a mobile subscriber. Unlike traditional P2P (Person-to-Person) SMS messaging — where two humans text each other—A2P messaging requires a system capable of handling massive volumes, ensuring high delivery rates.
In the world of telecommunications, A2P SMSC is the engine behind every one-time password (OTP), shipping notification, and marketing alert you receive. At the heart of an A2P SMSC is an SMSC that is specially designed and performance optimized for the A2P SMS traffic.

Key Functions of an A2P SMSC

• Billing & Reporting: It generates Delivery Receipts (DLRs), indicating sender whether the SMS was successfully delivered or needs a potential retry.
• Message Buffering: If a recipient is unavailable, the SMSC holds the message (Store-and-Forward) and retries delivery based on a set retry schedule.
• Protocol Conversion: It bridges the gap between internet protocols (used by apps) like SMPP and signaling protocols like SS7 or SIGTRAN (used by mobile networks).
• Throttling & Load Balancing: To prevent network congestion, the SMSC manages the “flow” of messages, ensuring that a massive marketing blast doesn’t crash the system.
• The Rise of “Grey Routes”: In the A2P world, security is a major focus. Historically, some entities used “Grey Routes”—sending commercial A2P traffic through P2P channels to avoid paying higher enterprise fees. Modern A2P SMSCs are equipped with SMS Firewalls to detect and block this traffic, ensuring carriers get paid and users aren’t spammed.

Why “A2P” SMSCs are Different: Standard SMSCs were originally designed for low-volume human to human interactive SMS messaging. However, an A2P-optimized SMSC includes features that standard ones lack:

Benefits of A2P SMSC:

• High SMS throughput through direct connectivity with mobile network operator
• Network errors received from mobile networks can be used to clean-up subscriber database effectively
• Real-time delivery reports.
• Support for efficient incoming and outgoing signaling with support for “moremessagestosend”
• Support for “TCAP Handshake” providing security against possible fraudulent SMS transactions
• Direct connectivity to mobile operator would offer higher capacity with dedicated CPU processing
• Flash SMS is supported
• UCS-2 encoding supported
• MVNO like behavior supported with incoming MT-SMS handling
• Option for M2PA and M3UA connectivity
• High capacity supported with small computing infrastructure
• Transaction logs for capturing details of each SMS transaction
• Small compute machines can be used to handle significant traffic volumes
• Both TRX and TX/RX modes of SMPP connectivity supported
• Multiple simultaneous bind sessions from an SMPP ESME supported