- SMS reaches any mobile phone; WhatsApp needs the app, data and customer opt-in.
- WhatsApp supports richer messages and replies; SMS is plain text.
- Both need approved templates and consent in India.
- Using both gives better coverage than either alone.
Reach and delivery
SMS works on every handset with network coverage, with no app or internet connection. WhatsApp reaches only customers who use it, have data access and have agreed to receive your messages. For a customer base that includes feature phones or low-data users, SMS is the dependable baseline.
Content and conversation
| Factor | SMS | WhatsApp Business API |
|---|---|---|
| Reach | Any mobile phone | Customers on WhatsApp who opted in |
| Format | Plain text, short | Text, images, documents and buttons |
| Replies | Limited, usually a keyword | Two-way conversation with your team or a bot |
| Approval | DLT headers and templates | Meta-approved templates |
| Best for | OTPs, short alerts, fallback | Tracking, returns help, support |
Consent and rules
Both channels need permission. For SMS, follow TRAI rules including DLT-approved templates. For WhatsApp, customers must opt in and business-initiated messages use templates approved under the correct category; Meta's documentation describes the requirements. Record when and how each customer agreed.
A practical setup
- Collect the customer's number and consent at checkout, with separate wording for WhatsApp.
- Send order confirmation and shipping updates on WhatsApp for opted-in customers.
- Send the same key updates by SMS to everyone else, and OTPs by SMS.
- Use WhatsApp replies for returns and delivery questions, handled by a team or bot.
See order notifications, the WhatsApp Business API and bulk SMS services.
Sources and further reading
Rules and platform requirements change. Last reviewed . This guide is general information, not legal advice.