WhatsApp Business API for lead follow‑up: what you can automate

Rules and rates reviewed on October 17 2026 in Meta’s official documentation, updated September 30 2026. Meta only changes rates on the first day of each quarter: check the source before budgeting.

With the WhatsApp Business API you can automate the first message to a lead, qualification with a few questions, assignment to a salesperson, appointment reminders, and re‑engagement of cold leads. What you cannot do is send a free‑form text first: outside the 24‑hour window you may only send templates approved by Meta. Since October 1 2026, each marketing template to a Mexican number costs 0.0397 USD.

In Mexico almost every sale goes through WhatsApp. The question is not whether to use it, but how to make sure every conversation is recorded and has an owner.

What is the WhatsApp Business API and how is it different from the app?

The WhatsApp Business app is the one you install on a phone: free, meant for one person to answer. The API (Meta calls it WhatsApp Business Platform) connects a number to your CRM or a messaging platform so several people, automations and bots can answer from the same number.

	WhatsApp Business app	WhatsApp Business API
Cost	Free	Pay per delivered message, plus the platform you use
Who answers	The phone holder	A team, automations and bots
CRM connection	Manual	Direct: every conversation is stored in the contact
Messages you start	Free‑form	Only with Meta‑approved templates
Reports	Very limited	Response times, conversations per salesperson, results

Meta lets you connect a number you already use in the app to the API and keep using both; it calls this coexistence and it has limits (for example, groups and calls do not work from that number). For a sales team I prefer a dedicated number that does not depend on anyone’s phone.

What can you automate in lead follow‑up?

Moment	What is automated	Message type	Cost per message in Mexico
Lead arrives from a form	First message in minutes with their name and request	Template (utility or marketing, depending on text)	0.0085 or 0.0397 USD
Lead replies	Two or three questions to qualify and a meeting proposal	Service, within the 24‑hour window	1,000 free per month per number; after that 0.0085 USD
Appointment set	Confirmation and reminder the day before	Utility template	0.0085 USD
Lead asks price, negotiates or complains	Pass to a salesperson with a summary of what was already said	Service	Same as above
Lead stops replying	Reactivation message at 7 or 15 days	Marketing template	0.0397 USD
Lead comes from an ad that opens WhatsApp	Entire initial conversation	Any	Free in the free‑entry window, up to 7 days

The best results come from combining channels. In the flows I build, a lead who fills a form gets an automated call in one or two minutes and, if they don’t answer, a WhatsApp message. Speed of the first contact matters most for conversion, and a system can do it any time. I explain how it works in automatización con IA en marketing.

What is not worth automating?

• Price and negotiation. The bot invites the meeting; the salesperson gives the current price. If the bot gives an old price, the problem is yours.
• Complaints. A angry customer who talks to a bot gets more upset. Hand them to a person in the first message.
• Long interrogations. If the bot asks six questions before offering anything, the lead leaves. Two or three questions, then the meeting.
• Choosing a salesperson. Let the CRM assign based on clear rules, not the bot or the first responder.

How much does the WhatsApp API cost in Mexico?

Meta charges per delivered message. These are the rates for Mexican numbers effective October 1 2026:

Category	Use case	USD per message	MXN per message
Marketing	Promotions, re‑engagement, invitations	0.0397	0.7298
Utility	Confirmations, reminders, request notices	0.0085	0.1565
Authentication	Verification codes	0.0085	0.1565
Service	Free‑form replies within the 24‑hour window	0.0085, after the first 1,000 per month	0.1565, after the first 1,000 per month

The peso amounts are what Meta’s official calculator shows. Utility and authentication have volume discounts.

Three recent changes many guides still miss:

1. Since October 1 2026 Meta started charging for service messages again, which were free from November 2024. Each number gets 1,000 free per month, then charges apply from the 1,001st message.
2. Utility templates sent inside the 24‑hour window are now charged again. They had been free since July 2025.
3. The free‑entry window can last up to 7 days. If a lead writes you from an ad that opens WhatsApp or from your Facebook page button, and you reply within the first 24 hours, messages in that window are not charged.

Example: 400 leads per month

Assume 400 form leads per month. Each receives a utility welcome template and an appointment reminder. Half of them also get a marketing re‑engagement. In total there are 3,200 service replies:

Item	Calculation	USD per month
Welcome and reminder (utility)	800 × 0.0085	6.80
Reactivation (marketing)	200 × 0.0397	7.94
Service replies	(3,200 − 1,000 free) × 0.0085	18.70
Total to Meta		33.44

What you pay Meta is the smallest part. The expensive part is the platform that links WhatsApp to your CRM, which charges separately based on the number of users and the time needed to set it up well.

What is the 24‑hour window?

When a lead writes you, a 24‑hour window opens during which you can reply with free‑form text, audio, images or documents. Each new message from the lead resets the window. When it closes, you can only send an approved template from Meta.

In practice this defines your process: if a salesperson takes two days to answer, they can no longer send a casual “How’s it going?” They must use a template, which costs money and can be rejected by Meta if it looks like spam.

Can I use an AI bot?

Yes, if it assists customers about your business. Since January 15 2026 Meta only allows AI providers to offer general‑purpose assistants, like ChatGPT, where the law requires it. The rule applies to companies whose product is AI, not to a company that uses AI to serve its own customers. Since July 1 2026 there is also a category for messages from Meta’s own AI agent, which is charged per token.

Rules I apply to any sales bot:

• It introduces itself as a virtual assistant. If asked whether it is a person, it says no and that a human advisor will take over.
• It does not give prices, availability or payment terms. It does not invent data that is not in its approved knowledge base.
• It does not create false urgency.
• It hands the conversation to a human when price, negotiation, complaint or any out‑of‑scope question appears, providing a summary so the salesperson does not repeat questions.

How does WhatsApp connect to the CRM?

The most important rule is one person, one salesperson: the owner of the WhatsApp contact must be the same owner in the CRM and in the business. When two systems assign leads on their own, the usual problem occurs: the lead fills a form, the CRM assigns a salesperson, then the lead writes on WhatsApp and the messaging platform gives it to someone else. Two salespeople end up talking to the same person.

To avoid this, decide which system assigns leads and let the other only copy the assignment. Review three numbers in the CRM each week: time to first contact, leads without reply, and appointments booked via WhatsApp. If your CRM does not see what happens in WhatsApp, check cómo elegir un CRM que sí vas a usar; the criteria work for any industry.

What I would do

1. Move sales WhatsApp from personal phones to a dedicated number linked to the CRM.
2. Request the needed templates from Meta: welcome, appointment reminder and re‑engagement.
3. Automate the first contact and reminders, and leave price and negotiation to the salesperson.
4. Measure each week response time, appointments and sales by channel.

If you want me to review how you handle WhatsApp leads, agenda 30 minutos.