These are not competitors so much as three different jobs, and most businesses need at least two of them.
Reach
WhatsApp is effectively universal among Indian smartphone users, and crucially people actually read it. RCS reaches Android devices through Google Messages without an install, which covers a large share of the market but not iPhones consistently. SMS reaches everything, including feature phones.
What you can actually send
- WhatsApp: templates, carousels, catalogues, buttons, media, in-chat forms, payments
- RCS: verified sender, rich cards, carousels, images, video, suggested replies
- SMS: 160 characters and a link, from a shortcode nobody recognises
How each is charged
WhatsApp charges per template message delivered, at different rates for marketing, utility and authentication categories. RCS in India is charged per session by the carriers. SMS is charged per message and is the cheapest per unit, which is also why it is the most abused and the most ignored.
Comparing them on unit price alone is misleading. The useful comparison is cost per reply or cost per conversion, where WhatsApp usually wins despite the higher unit cost.
A sensible split
- Marketing and conversations: WhatsApp first
- Android users who never engage on WhatsApp: RCS as a second attempt
- Authentication and OTP: SMS remains reliable and cheap
- Critical alerts: send on two channels rather than hoping
- Feature-phone or low-connectivity audiences: SMS is still the only option
Running them together
The practical pattern is WhatsApp as the primary channel with RCS as a follow-up to Android contacts who did not receive or engage, and SMS reserved for transactional messages where delivery certainty matters more than richness.
Running both WhatsApp and RCS campaigns from the same dashboard makes this a targeting decision rather than a procurement project.