Integrated OTP SMS India: Generate and Verify OTPs With Two API Calls
Add one-time password login and verification to your app, website or CRM without building OTP logic yourself. SMSGatewayCenter generates the code, delivers it by SMS on a DLT-compliant transactional route that reaches DND numbers 24/7, and verifies what your user types back.
What is Integrated OTP SMS?
Integrated OTP SMS is SMSGatewayCenter's one-time password API. You make one call to generate an OTP, which is sent to your user's mobile number by SMS, and one call to verify the code the user types back. It removes the need to generate, store, expire and check OTPs yourself.
Passwords alone no longer give enough security for logins and high-value transactions. A one-time password confirms that the person is who they say they are, and it protects your app or website from fraud and unauthorized access. Typical uses are login, mobile number verification, payment confirmation and member registration for banks, e-commerce and apps.
| Integrated OTP SMS at a glance | |
|---|---|
| API calls | Generate and verify, set with sendMethod |
| Code options | Length such as 4 or 6, type numeric, alpha or alphanumeric |
| Default validity | 300 seconds, changed with codeExpiry |
| Delivery | SMS, with optional WhatsApp or RCS fallback |
| India compliance | Approved sender ID and DLT-registered template |
| Delivery tracking | API response callback to your URL |
| Response format | JSON or plain text |
| Works with | Any HTTP client, a PHP class file, WordPress and Magento |
From mobile number to verified user in six steps
Your server makes two calls. Everything in between, from code generation to SMS delivery, is handled by SMSGatewayCenter.
- Collect the mobile number. Your user enters their mobile number in your app or website.
- Call the generate API. Your server calls the OTP API with sendMethod=generate, the mobile number, your sender ID and the message.
- The OTP is delivered by SMS. SMSGatewayCenter generates a time-based unique code and delivers it to the user's mobile number.
- The user enters the code. Your user types the code they received on your verification screen.
- Call the verify API. Your server sends the mobile number and the code to the OTP API with sendMethod=verify.
- Act on the result. The API returns success or failure, and your app takes the next step, such as logging the user in.
We also provide a PHP class file so you can use the API without the usual development hassles.
Stop building your own OTP logic
Generating, storing, expiring and checking OTPs yourself means four moving parts to maintain. With the OTP API you make two calls.
Generate
sendMethod=generate creates the OTP and sends it by SMS. You set the code length, type (numeric, alpha, alphanumeric) and expiry (default 300 seconds).
Verify
sendMethod=verify checks the code your user typed and returns success or failure.
In India, OTP SMS needs an approved sender ID and a DLT-registered template. Watch it on YouTube
The real endpoint, the real responses
Both calls go to the same endpoint. Authenticate with your account credentials or an API key (see the docs), and URL-encode the message. In the message, $otp$ is replaced by the generated code, and the text has to follow your DLT-registered template. Full parameter lists are in the Generate OTP API and Verify OTP API docs.
Everything you need to verify users by OTP
One platform covers generation, delivery, tracking and verification.
Generate and verify in one place
Create and check OTPs on SMSGatewayCenter's own platform through one API. No third-party OTP service to wire in.
Dedicated OTP route
Dedicated delivery pipes are assigned to OTP traffic, built for fast delivery of time-sensitive codes.
Operator retry
If an operator is down, delivery is retried through other operators so the code still reaches your user.
API response callback
Delivery responses are forwarded to your callback URL. Store them in a database, email them, or write them to a file.
Multi-Channel Fallback
When SMS alone is not enough, retry OTP delivery on WhatsApp or RCS with mapped templates.
Explore fallbackDelivery to DND numbers
As a transactional SMS service, OTPs can be delivered to DND numbers 24/7, as per TRAI regulations.
Configurable codes
Choose the code length, such as 4 or 6, the type (numeric, alpha, alphanumeric) and the expiry. The default is 300 seconds.
Ready-made integrations
Use the HTTP API from any stack, the PHP class file, or platforms such as WordPress and Magento.
WordPress login OTPGlobal reach
Deliver OTPs to networks worldwide, subject to country-specific regulations. Contact our support team for details.
Where one-time passwords earn their keep
Add a verification step wherever you need proof that the person is who they say they are.
Login verification
Confirm it is really your user signing in, as a second factor on top of a password.
Mobile number verification
Check that a number belongs to the user before you save it to their account.
Payment confirmation
Authorize high-value transactions with a one-time code before they go through.
Member registration
Verify new sign-ups on your site or app so only real numbers get accounts.
Build your own OTP logic, or make two calls
The difference is how much you have to maintain.
Doing it yourself
- Generate the codes
- Store them
- Expire them
- Check what the user typed
With Integrated OTP SMS
- Two API calls: generate and verify
- Code length, type and expiry set in the request
- SMS delivery on a DLT-compliant transactional route
- Delivery responses sent to your callback URL
What you need before sending OTP SMS in India
OTP SMS is a regulated message type. Two items have to be in place before your first send.
An approved sender ID
Your sender ID is the name your OTP appears from. It has to be registered and approved before you send.
A DLT-registered template
The OTP message you send has to follow a template registered on the DLT platform.
DLT registration guideA transactional route
OTPs go out as transactional SMS, which is what lets them reach DND numbers 24/7 as per TRAI regulations.
Transactional SMSFrequently Asked Questions about Integrated OTP SMS
Integrated OTP SMS is SMSGatewayCenter's one-time password API. You make one API call to generate an OTP, which is sent to your user's mobile number by SMS, and a second call to verify the code the user types back. It removes the need to build OTP generation, storage, expiry and checking yourself.
Call the OTP endpoint with sendMethod=generate, the mobile number, your approved sender ID and the message, and optionally the code length, code type and expiry. The OTP is created and sent by SMS. When the user enters the code, call the same endpoint with sendMethod=verify, the mobile number and the code. The response tells you whether verification succeeded or failed.
The default validity is 300 seconds, which is 5 minutes. You can change it for each request with the codeExpiry parameter, which takes a value in seconds.
You set the code length with codeLength, for example 4 or 6 digits, and the code type with codeType: numeric, alphabetical or alphanumeric.
Yes. OTP SMS in India needs an approved sender ID and a DLT-registered message template, and the OTP message you send has to follow that template. SMSGatewayCenter provides a DLT registration guide to help you complete this.
Yes. As a transactional SMS service, OTP SMS can be delivered to DND numbers 24/7, as per TRAI regulations.
Delivery is retried through other operators if an operator is down, and delivery responses are forwarded to your callback URL so you can track and resolve issues. If you also use Multi-Channel Fallback, the OTP can be retried on WhatsApp or RCS using mapped templates.
Yes. You write the OTP message in the msg parameter and place the generated code where you want it with the $otp$ placeholder. The message has to follow your DLT-registered template.
Any system that can make an HTTP request, including websites, mobile apps and CRMs. SMSGatewayCenter also provides a PHP class file, and the API works with platforms such as WordPress and Magento.
OTPs are single-use with short expiry times and are delivered through a dedicated gateway, which helps protect against fraud and unauthorized access.
Yes, OTPs can be delivered to networks worldwide, although restrictions may apply based on country-specific regulations. Contact our support team for details.
OTP SMS pricing is listed on the OTP SMS pricing page, which covers the Super High Priority OTP SMS route plans.
Need more answers? Explore our knowledge base.
Add OTP verification to your app
Compare the Super High Priority OTP SMS route plans, or tell us about your volumes and we will help you integrate. You can also write to us at contact @ smsgatewaycenter.com.
