SMPP (Short Message Peer-to-Peer) is a binary protocol used by telcos and high-volume SMS aggregators. REST APIs are HTTP-based interfaces designed for application developers. Both can deliver OTP messages — but they serve different audiences.
SMPP in brief
- Persistent TCP connection to an SMSC or aggregator
- Maximum throughput for bulk messaging at scale
- Requires protocol expertise and connection management
- You still build OTP logic (codes, expiry, validation) yourself
REST OTP API in brief
- Simple HTTP POST requests — works with any language or stack
- OTP lifecycle handled for you: send, check, signed tokens
- Built-in fraud controls and per-success pricing
- No persistent connections or telecom infrastructure to manage
Comparison
| Factor | SMPP | REST OTP API |
|---|---|---|
| Integration complexity | High | Low |
| OTP logic | Build yourself | Included |
| Best for | Bulk SMS at telco scale | App verification flows |
| Developer experience | Ops-heavy | API-first |
Unless you're operating an SMS gateway, a REST OTP API like DoneOTP is the faster path — two endpoints, global delivery, pay per successful verification.