WhatsApp Business API is the version of WhatsApp built for companies that serve many customers. Unlike the regular app or WhatsApp Business on a single phone, the API supports multiple agents, integrations, templates and automation.
This guide explains what the WhatsApp Business API is and how it differs from the regular app. For the steps and costs in Costa Rica, go to WhatsApp Business API in Costa Rica.
API vs the regular app
- Regular / Business app: a single device, manual handling, no integrations.
- WhatsApp Business API: multiple agents in one inbox, approved templates, bots, and a connection to your CRM or platform.
What it is used for
Customer support, appointment and payment confirmations, notifications, OTP codes and campaigns. With a flow bot you can automate answers 24/7 and hand off to an agent when needed.
Templates and opt-in
To start conversations (outside the 24-hour window) you use templates approved by Meta. And you always need the customer's opt-in to message them. All of this is managed from the platform.
How to get started
You need an enabled number and a WhatsApp Business account. At TelHarbor we set it up and connect it to your inbox. See the Business WhatsApp page.
The 24-hour window, explained
This is the rule that confuses people most and blocks the most messages. It works like this: when a customer writes to you, a 24-hour window opens during which you can reply with free text, images and whatever else you need. After 24 hours without the customer writing again, the window closes.
With the window closed, you can only start the conversation with an approved template. Try to send free text and the message simply does not arrive. This is the source of almost every "I messaged them and it never got there".
The practical consequence: if an agent leaves a conversation unanswered until the next day, they cannot just pick it up; they have to reopen it with a template. Which is why having an approved re-engagement template ready in advance pays off.
Templates: how they get approved and why they get rejected
A template is a predefined message with variables. It goes to review and is usually approved within minutes or hours. Rejections happen for fairly consistent reasons:
- Promotional text declared as utility.
- Variables at the very start or end of the message, or two variables in a row.
- Content that makes no sense without context ("Hi {{1}}, your {{2}} is ready").
- Spelling mistakes or unclosed formatting.
- Promising something the category does not allow.
Tip: write the template as if the reader knew nothing about your company, because the reviewer genuinely does not.
Categories and why they hit the invoice
- Utility: confirmations, order updates, appointment reminders. The cheapest.
- Authentication: one-time passcodes.
- Marketing: promotions and campaigns. The most expensive and the strictest on consent.
- Service: replies inside the 24-hour window the customer opened.
Declaring the wrong category is not only a cost issue: send marketing under a utility category and it gets recategorised or rejected.
Mistakes that cost customers
- Messaging people who never consented. Beyond being blocked, it generates spam reports that damage the number's quality rating.
- Mixing personal and company numbers. A number connected to the API can no longer be used in the regular app.
- Having nobody on the other side. WhatsApp creates an expectation of fast replies; an open, unattended channel is worse than none.
- Automating everything. A bot should filter and handle the repetitive part; there must always be a way through to a person.
Frequently asked questions
Can I use my current number?
In many cases yes, if the number is not already in the WhatsApp app; it gets enabled for the API.
How many agents can handle it?
Several at once, from a single inbox, with the history of each conversation.
Can it be automated?
Yes. With menus, flow bots and auto-replies, with handoff to an agent.
Can I use my current WhatsApp number?
Yes, but connecting it to the API stops it working in the regular app. That is why many companies prefer a dedicated number.
Why is my message not reaching the customer?
Almost always because the 24-hour window closed and you are sending free text. Outside the window only approved templates get through.
How long does template approval take?
Usually minutes to a few hours. Rejections are typically about a wrongly declared category or text that makes no sense without context.
Do I need a bot?
Not mandatory, but it helps: it filters the repetitive part and answers after hours. It should always leave a route through to a person.