OTP SMS (One-Time Password) is the backbone of digital authentication in India - used for login, payments, KYC, and account recovery. This guide covers compliance, routing, and integration best practices.
DLT Requirements for OTP
Every OTP message in India must be sent through a DLT-registered transactional template with an approved sender ID (header). Promotional templates cannot be used for OTP.
- Register your business entity on the DLT portal
- Approve a transactional sender ID (e.g. SMSTKE)
- Register OTP template with variable placeholder for the code
- Map template to your SMS provider (SMSTAKE)
OTP Message Best Practices
- Keep OTP length 4 - 6 digits; expire within 5 - 10 minutes
- Include brand name and purpose in template text
- Use secure fallback channels for high-risk verification flows
- Rate-limit resend requests per phone number
- Use webhooks to confirm delivery before showing errors
API Integration Example
Send OTP via SMSTAKE REST API with your DLT template ID:
POST /v1/messages/send
{
"to": "+919876543210",
"channel": "sms",
"sender": "SMSTKE",
"message": "Your OTP is 482910. Valid 5 min. - SMSTAKE",
"dlt_template_id": "1207165123456789012"
}OTP Delivery Performance
Choose a provider with priority transactional routes and direct operator connectivity. SMSTAKE targets sub-second dispatch and 99.99% delivery for OTP traffic across Jio, Airtel, Vi, and BSNL.
Fallback option: Voice OTP when SMS delivery fails - available on the same SMSTAKE platform.