WhatsApp vs SMS for business: what each costs, what each is for, and why reminders go on WhatsApp and codes go on SMS

SMS still works on every phone with no app and no internet, and businesses have sent reminders and codes on it for twenty years. WhatsApp is where customers now reply. The choice is not one or the other; it is which messages belong on which. Here is the comparison, including what each costs.

By Ritchie, ReplyKit · Published 5 September 2026 · 6 min read

Quick answer

SMS costs per message (a few cents each through a gateway, varying by country), reaches any phone, and is one-way in practice; customers rarely reply. WhatsApp replies to inbound customers cost nothing on the free app, support photos, voice and links, and customers answer back, which is what makes reminders with a confirm reply and booking conversations work. Use WhatsApp for conversations, reminders, confirmations and support; use SMS for authentication codes, customers without WhatsApp, and regulated notices that must reach any handset. Marketing on either needs consent.

Side by side Where WhatsApp wins Where SMS wins The split FAQ

Side by side

	WhatsApp	SMS
Cost to reply to a customer	Free on the app; per message on the official API	Per message, typically a few cents via a gateway
Cost to send a reminder	Free on the app within limits; per template on the API	Per message
Reach	Anyone with WhatsApp, which in Malaysia and Singapore is most people	Any phone, no app or data needed
Two-way	Yes, conversational	Technically, rarely in practice
Media	Photos, voice, documents, location, links with preview	Text and short links
Sender identity	Business profile, name, photo, optional verified badge	Sender ID or number; spoofing concerns
Spam rules	Reports restrict numbers; consent required for outbound	Regulator rules and carrier filtering; consent required
Automation	AI agents can converse	One-way sequences
Read behaviour	Read receipts	None

Gateway SMS pricing varies by country and volume; see for example Twilio's SMS pricing. WhatsApp's official API pricing is in API pricing explained.

Where WhatsApp wins

Anything a customer might reply to: reminders with a confirm reply, booking changes, order questions, support.
Rich content: a photo of the product, a location pin, a PDF quote.
Cost for conversations: replying on the app is free.
An AI agent can hold the conversation; SMS has nothing to converse with. The reminder evidence is in reducing no-shows.

Where SMS wins

Authentication codes and security notices, where every handset must receive it.
Customers without WhatsApp or data, including some older customers and feature phones.
Regulated notices where a delivery record on the carrier network matters.
Very high volume one-way alerts where cost per message is predictable.

The split

Message	Channel
Appointment reminder with confirm	WhatsApp
Order and delivery updates	WhatsApp, with SMS fallback for customers without it
Login or payment code	SMS
Customer enquiry replies	WhatsApp
Marketing to opted-in customers	WhatsApp Status or opted-in lists; SMS for opted-in customers without WhatsApp
Emergency or regulated notice	SMS, plus WhatsApp

Where the connection matters: ReplyKit runs on Meta's official WhatsApp Business Platform, so there is no linked-device pairing and no restriction risk from automation. Meta's per-message fees apply only to reminder and follow-up templates sent outside the 24-hour window; replies to customers who message you carry no Meta fee inside it. The trade-offs are explained in why ReplyKit runs on the official platform.

Frequently asked questions

Is WhatsApp cheaper than SMS for business?

Replying to customers on the WhatsApp app is free; SMS costs per message. On the official WhatsApp API, outbound templates cost per message too.

Do customers reply to SMS?

Rarely. They reply on WhatsApp, which is why reminders with a confirm reply work there.

What should stay on SMS?

Authentication codes, customers without WhatsApp, and regulated notices that must reach any handset.

Can I send marketing on SMS or WhatsApp?

Only to people who consented, on either. WhatsApp additionally restricts numbers that get reported.

Can an AI agent work over SMS?

ReplyKit works on WhatsApp and website chat. SMS is one-way in practice and not a fit for conversation.

Reminders that get a reply

WhatsApp conversations answered and confirmed by the agent. 7-day free trial.

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Written by Ritchie, ReplyKitPart of the small team in Malaysia that builds and runs ReplyKit. Writes about WhatsApp automation, AI customer service and small business lead response.

How we know this. ReplyKit customers often arrive from SMS reminder services; the reminder and confirmation comparison below is drawn from that switch, with SMS costs from published gateway pricing. Product figures in this article (limits, prices, per-reply costs) are taken from ReplyKit as it runs today and are re-checked when we update the page. Where we cite outside research, the source is linked below. We sell ReplyKit, so read our product claims with that in mind; we say where a different tool or no tool is the better choice. About ReplyKit.

Sources and further reading

Twilio, SMS pricing (checked September 2026)
Cochrane Review, Mobile phone messaging reminders for attendance at healthcare appointments (Gurol-Urganci et al., 2013) · reminder messages improve attendance compared with no reminder
WhatsApp Business Messaging Policy · opt-in, opt-out and prohibited-use rules every business must follow

ReplyKit is an independent product and is not affiliated with or endorsed by Meta or WhatsApp. SMS and API prices vary by country, provider and volume and change; check current pricing.