When you receive a one-time password (OTP) from a bank or a login code from Facebook, that message is not coming from a normal mobile phone. It is sent by an application through an A2P SMS gateway.
What Is A2P SMS?
A2P SMS stands for Application-to-Person SMS. It means text messages that are sent from a software platform to a human user. Unlike P2P (Person-to-Person) messaging where two people are chatting, A2P is one-way or system-driven messaging.
Common examples of A2P SMS include:
- OTP codes for login, registration and payment authorization
- Banking and fintech alerts (balance change, card transaction, cash withdrawal)
- E-commerce updates (order placed, shipped, delivered)
- Appointment reminders for clinics, schools, service centers
- Promotional and marketing campaigns (offers, new product launch, seasonal sale)
How A2P SMS Works – Step by Step
1. User or System Triggers an Event
Everything starts with a trigger. A customer clicks “Login with OTP”, places an order, or your system schedules a promotional campaign. Your application decides that an SMS needs to be sent.
2. Your Application Calls the A2P SMS Platform
Your application doesn’t talk directly to mobile operators. It sends the message to an A2P SMS platform such as an SMS gateway or aggregator using:
- HTTP/REST API – easy for web and mobile apps
- SMPP – telecom-grade protocol for high volume messaging
At OnnetBD IT, our OnSMS gateway accepts both HTTP and SMPP, so you can integrate in the way that best fits your architecture.
3. The Platform Chooses the Best Route
The A2P platform connects to many mobile operators and partners worldwide. It looks at the destination number (country + operator) and chooses the best route based on:
- Delivery speed – for OTP and mission-critical alerts
- Price – to keep your cost optimized
- Quality – whether the route is A2P-approved or a low-quality grey route
- Regulations – whether sender ID and content comply with local rules
4. Message Travels Through the Operator SMSC
Once the route is selected, the message is forwarded to the mobile operator’s SMSC (Short Message Service Center). The SMSC is responsible for queuing, forwarding and delivering SMS to subscribers' phones.
If the phone is switched off or out of coverage, the SMSC may keep the message for some time and retry delivery until it either succeeds or expires.
5. Delivery to the Handset and DLR
Finally, the message reaches the phone and pops up as a normal SMS. Meanwhile, the operator sends a DLR (Delivery Report) back to the A2P platform with a status such as:
- DELIVRD – delivered to handset
- FAILED – permanently failed
- EXPIRED – could not be delivered in time
- REJECTED – blocked by filter or policy
Your application can use this delivery data to monitor performance, measure OTP success rates, and retry or use a backup channel (email, WhatsApp, voice call) when needed.
Key Use Cases of A2P SMS
- Security & Authentication – OTP, 2FA, login verification
- Banking & Fintech – transaction alerts, OTP, fraud warnings
- E-commerce & Logistics – order confirmation, delivery updates
- Customer Engagement – promotions, surveys, reminders
- Government & Education – exam notifications, public announcements
Why Businesses Prefer A2P SMS
- Works on every phone – no app or internet required
- Extremely high open rate (over 90%+ are read within minutes)
- Global coverage with a single API integration
- Supports both transactional and promotional traffic
- Easy to automate from your CRM, ERP, or custom applications
How OnnetBD IT Can Help
At OnnetBD IT, we design complete A2P messaging solutions – from gateway deployment to custom dashboards and routing logic. Whether you are an enterprise, ISP, or telecom partner, we can:
- Deploy and maintain your own A2P SMS gateway (On-prem or Cloud)
- Integrate HTTP/SMPP APIs with your existing software
- Optimize routes for price vs. delivery speed
- Build reports and analytics for OTP success and campaign performance
👉 Want to implement A2P SMS for your business? Contact OnnetBD IT for a consulting session or a full solution demo.