Almost every confusing thing about WhatsApp pricing comes back to this one rule. Once it clicks, the rest is obvious.
The customer opens the door. While it is open you can talk freely and for free. When it shuts, you can only knock with a pre-approved template, and knocking costs money.
How it works in a normal day
Every message in that exchange is free, and the customer’s second message pushed the deadline another 24 hours out. A conversation that runs all afternoon costs nothing.
What happens after 24 hours of silence
Say the customer goes quiet and two days later you want to tell them their order shipped. That is now outside the window, so you need a template — a message format Meta approved in advance — and it is charged per delivery.
| You want to… | Inside the window | Outside the window |
|---|---|---|
| Answer a question | Free | Template required, charged |
| Send a photo or price | Free | Template required, charged |
| Send an order update | Free | Utility template, charged |
| Send a promotion | Not appropriate unasked | Marketing template, charged |
Why this shapes the whole business case
A shop that answers enquiries lives inside the window nearly all the time, so its WhatsApp bill is close to zero. A business built on blasting promotions lives outside it and pays for every message. The platform is deliberately priced to reward the first behaviour.
If your plan is "answer everyone who messages us, fast", WhatsApp is one of the cheapest sales channels available. If your plan is "message thousands of people who never asked", it is not.