Short answer
No single channel is best for every message. SMS reaches almost any mobile number and suits OTPs and essential alerts, but in India it must follow TRAI's DLT rules. WhatsApp suits two-way conversations with customers who use WhatsApp and have agreed to hear from you, and Meta charges per message. RCS adds rich cards and buttons in the phone's default messaging app, but only where the phone, network and your launched agent support it. Many businesses use SMS as the base and add RCS or WhatsApp where they help.
The same order update on three channels
Your order 12345 has shipped. Track it at example.com/t/12345 - Your Store
Your order 12345 has shipped and should arrive by Friday.
Your order has shipped
Side-by-side comparison
| SMS | RCS Business Messaging | WhatsApp Business API | |
|---|---|---|---|
| Where it arrives | The phone's SMS inbox | The default messaging app, mainly Google Messages on Android | The WhatsApp app |
| Who can receive it | Almost any mobile number | Customers whose phone, app and network support RCS, on networks where your agent is launched | WhatsApp users who have given you their number and opted in |
| Sender identity | A DLT-registered header with a category suffix | Brand name and logo; a verification mark after brand verification and launch | Your business display name and profile |
| Content | Text only: up to 160 GSM 7-bit characters, or 70 Unicode characters, per segment | Rich cards, carousels, images, video, suggested replies and actions | Text, media, documents, buttons and lists |
| Two-way chat | Customers generally can't reply to an alphabetic header | Yes - replies go to your agent | Yes; outside the 24-hour customer service window you must use approved templates |
| Rules and approvals | TRAI DLT: entity, header, template, consent and PE-TM chain | Brand verification and launch approval by Google and/or carriers | Meta's policies, opt-in and template approval |
| How it is priced | Per SMS segment, set by your provider | Billing models set by carriers and providers; confirm with your provider | Meta's per-message charges by category and country, plus provider fees |
SMS length depends on encoding: a message using only the GSM 7-bit alphabet fits 160 characters in one SMS, while any Unicode character - such as Hindi text or an emoji - lowers the limit to 70. Longer messages are split into segments. Our RCS guide explains encoding and segments in more detail.
Which channel should you choose?
Choose SMS when
- You need to reach almost every customer, whatever their phone
- You send OTPs or essential alerts
- A short text and a link are enough
Choose WhatsApp when
- Customers want to reply and chat
- You run support or order conversations
- Your customers use WhatsApp and have opted in
Choose RCS when
- Images, carousels or buttons help the customer act
- Many of your customers use supported Android phones
- You can plan an SMS fallback for everyone else
Combining channels
You don't have to pick one. Common combinations include:
- RCS with SMS fallback: send a rich message where RCS is available, and a plain SMS to everyone else. Fallback has to be configured, and the SMS needs a DLT-approved template.
- SMS for OTPs, WhatsApp for conversations: keep time-critical codes on SMS and move support to WhatsApp.
- One opt-in record: track which customers have agreed to which kind of message, so each channel follows its own consent rules.
A note on costs
Each channel is priced differently. SMS is usually charged per segment, so long or Unicode messages can cost more. For WhatsApp, Meta charges per delivered template message by category and country. From 1 October 2026, Meta also charges for service messages after a free tier of 1,000 per business phone number per month - see our WhatsApp pricing guide. RCS billing models are set by carriers and providers. We don't publish RCS prices here because they depend on the account and network.
Not sure which channel fits?
Tell us what you send, who you send it to and what you want customers to do next. We will help you compare SMS, RCS and WhatsApp for your use case.
Discuss Your Messaging RequirementsExplore each channel: Bulk SMS | RCS Messaging | WhatsApp Business API
Sources
Checked on 30 September 2026. Rules and prices change, so confirm current requirements with the official source before acting.
- TRAI - TCCCPR (Second Amendment) Regulations, 12 February 2025 (PDF)
- 3GPP TS 23.038 - Alphabets and language-specific information (GSM 7-bit character set)
- Google for Developers - RCS for Business: send messages
- Google for Developers - RCS for Business: verify and launch your agent
- Meta for Developers - WhatsApp Business Platform pricing
- Meta for Developers - Get opt-in for WhatsApp