Every business sending SMS OTPs is paying a per-message cost that adds up fast at real volume — and most haven’t compared it against what the same OTP costs over WhatsApp.
The actual numbers
WhatsApp authentication messages in India run roughly ₹0.115 per delivered message, against ₹0.15–0.35 for SMS OTP depending on volume and route. That gap compounds at scale: sending 100,000 OTPs a month costs a fraction on WhatsApp compared to SMS — a difference that shows up directly in the infrastructure bill every month, not just a one-time saving.
It’s not only about cost
- Higher deliverability — WhatsApp OTP delivery rates are reported meaningfully higher than SMS, which matters more than the per-message price when a failed OTP means a lost signup or a support ticket.
- Auto-read support — some implementations let the OTP auto-fill without the user manually copying a code, a small UX detail that reduces drop-off at exactly the moment someone’s trying to complete a signup or login.
- One less vendor relationship — if you’re already running WhatsApp Business AI, adding authentication messages is one more thing running on infrastructure you already operate.
The caveat worth knowing
The savings are largest for a domestic Indian user base — international authentication rates are substantially higher than domestic ones, so the math changes for a business with a meaningful share of users outside India. Worth checking your actual user geography before assuming the numbers above apply directly.
Where this fits
OTP and authentication messages are part of what’s covered under WhatsApp Business API Provider — template approval for authentication messages, alongside marketing and utility templates. Tell us your current OTP volume and we’ll work out what switching actually saves.