Businesses today have three main ways to send messages to a customer's phone: classic SMS, WhatsApp and RCS (Rich Communication Services). Each has different strengths, and choosing well can lift delivery, engagement and conversions while keeping costs in check.
Quick comparison
| SMS | WhatsApp Business API | RCS Business Messaging | |
|---|---|---|---|
| Reach | Every mobile phone, no internet needed | Users who have WhatsApp (the large majority of smartphone users in India) | Supported Android phones in the default messages app; support on other devices depends on carrier and country |
| Content | Text only | Text, images, documents, buttons, lists | Images, carousels, suggested replies and buttons |
| Branding | Sender ID only | Business name, logo and profile | Verified brand name, logo and colour |
| Two-way chat | Limited | Yes, built for conversations | Yes |
| Best for | OTPs and must-deliver alerts | Support, updates and conversational journeys | Rich promotions and interactive journeys |
When to use SMS
SMS is the most universal channel. It works on every phone, with or without data, which makes it the safest choice for OTPs and critical alerts. In India, business SMS must be registered on the DLT platform before it can be sent.
When to use WhatsApp
WhatsApp is ideal when you want a conversation — answering questions, sending invoices, confirming bookings or running a chatbot. Customers already use it every day, so read and reply rates are typically high. Read our WhatsApp Business API guide for how it works and how pricing is structured.
When to use RCS
RCS upgrades the default messaging app with app-like features: brand logo and verified sender, image carousels, and tappable buttons such as "Track order" or "Pay now". It is a strong fit for promotions, product catalogues and interactive journeys — without asking customers to install anything. Where RCS is not supported, providers can fall back to SMS automatically.
The smart setup: combine channels
- Send OTPs by SMS (or WhatsApp authentication messages) for maximum reach.
- Run support and order updates on WhatsApp, where customers can reply.
- Use RCS for rich promotions on supported devices, with automatic SMS fallback.
- Track delivery and response for each channel and shift volume to what performs best.
Not sure which channel fits your business? Book a free consultation or explore our RCS messaging service.
Frequently asked questions
What is RCS messaging?
RCS (Rich Communication Services) is the upgraded version of SMS. It lets businesses send branded, verified messages with images, carousels and buttons inside the phone's default messaging app.
Is RCS better than SMS?
RCS is richer and more interactive, but SMS reaches every phone. Most businesses use RCS where it is supported and fall back to SMS automatically everywhere else.
Should I use WhatsApp or SMS for OTPs?
SMS has the widest reach and works without internet, so it remains the safest default for OTPs. Many businesses add WhatsApp authentication messages as a second option.
Need help with this?
Our senior team can scope it with you in a free 30-minute call — no salespeople, no pressure.