Put an AI agent on your WhatsApp without breaking things

You have a WhatsApp Business number that has been working for years. Inside it sits the history of half your customer base, the colour-coded labels you set up one slow afternoon, and the back-office laptop linked to it. Now you want an AI agent answering on that same number. The question everyone asks at this point is the same one: what breaks? Short answer — less than you fear, but not nothing. Here is the exact list, and what to sort out before anyone presses the button.

You no longer have to choose between the app and the agent

For a long time, "I want an agent on my usual number" got an awkward answer: either the phone app or the API, but the two could not share a number. Which led to the ugly workaround of buying a second number for the agent and asking customers to message that one instead. Nobody ever does.

That's no longer how it works. Meta documents an onboarding mode — you'll see it called coexistence — where your number stays in the app on the phone and is connected to the Cloud API at the same time, which is where the agent lives. One-to-one messages mirror both ways: if the person on the front desk replies from the phone, the agent sees it; if the agent replies, the thread shows up on the phone as though a human typed it. Same number, same history, same front door.

Four things that switch off on day one

Now the honest part. Connecting the number has a toll, and it's written down in Meta's documentation on onboarding WhatsApp Business app numbers. Here's what changes the moment you finish:

• Broadcast lists go read-only. You can't create new ones, and the ones you have stop working for sending. If your way of telling two hundred customers about the September offer was a broadcast list, that gets rebuilt with templates — which is the route that doesn't get your account restricted anyway.
• Every linked device is unlinked. The office WhatsApp Web session, the tablet on the counter: all of it drops during onboarding and has to be re-linked by hand. Up to four are supported, with two that never come back: WhatsApp for Windows and WhatsApp for WearOS.
• Disappearing messages, view-once and live location are turned off in one-to-one chats. If your team shares live location so the customer knows the engineer is on the way, find the replacement before onboarding day.
• Group chats don't sync. They keep working in the app exactly as before, but the agent can't see them or post in them. If half your job coordination lives in a group with the customer and the site manager, that part sits outside the agent's perimeter.

None of the four is a disaster if you know in advance. All four are a bad day if you find out as it happens.

History: six months, one shot, 24 hours

This is the step most people skim, and the one that costs the most later.

During onboarding a screen asks whether you want to share your conversation history. Say no and the agent starts blind — no idea what you promised to whom, or where each thread had got to. It's workable, but it's starting with one hand tied.

Say yes and the last 180 days of messages sync across. With three bits of small print:

1. You only get one attempt. If it goes wrong, you disconnect the account and redo the whole onboarding.
2. Your provider has 24 hours from onboarding to pull that history down. Miss the window and it's the same remedy.
3. Older attachments arrive half-empty. Files from the last two weeks sync properly; anything older shows up as a placeholder, without the photo or the PDF. The text is there.

Practical consequence: this isn't something you start at seven on a Friday evening. Do it with your provider on the phone, the number's handset in front of you, and let the sync finish before you shut up shop.

What stays living only in the app

There's a second list — less dramatic, more treacherous. Things that keep working perfectly in the app and that the agent simply can't see.

Labels, quick replies, greeting and away messages, the catalogue and orders, the business profile, voice and video calls, Channels. None of it breaks. It just lives on one side and not the other.

The trouble starts when you've spent three years sorting customers with a label that says "Quote sent" and you assume the agent knows what that means. It doesn't. That information has to reach it another way: a spreadsheet, your CRM, whatever you quote from.

One detail that shows up on the invoice: what your team sends from the app stays free, while what the agent sends through the API is billed at Cloud API rates. And the 24-hour service window only counts for what goes out through the API — a colleague replying from the phone neither opens it nor extends it for the agent. If someone answers by hand on Monday and you expect the agent to pick the thread back up on Wednesday, it will have to use a template, and templates cost money.

Half an hour of prep before the button

This isn't a project. It's one quiet afternoon and this list:

1. Update the app. Meta requires version 2.24.17 or later on the phone where the number lives.
2. Pick the primary handset and leave it alone that week. Swapping phones mid-process is the fastest way to start over.
3. Write down your linked devices first. They're all coming off, and without the list you'll discover on Thursday that accounts hasn't seen a message in two days.
4. Get what's trapped in your labels out. Note which customers are at which stage: it's exactly what the agent needs and exactly what won't reach it through the channel.
5. Prepare the template that replaces your broadcast lists and submit it for approval with time to spare.
6. Warn the team in one sentence. "Thursday morning we connect the number; the WhatsApp Web session will drop and replies nobody on the team wrote will start appearing." Without that, the first automated reply generates three panicked phone calls.
7. Pick the hour properly. Tuesday or Wednesday morning, with people around. Never a Friday, never the day before a bank holiday.

When not to connect yet

Four situations where I'd wait.

If your day-to-day genuinely runs in groups with customers and suppliers, the agent is watching from outside. Decide first what moves out of the group and into one-to-one.

If the number is on regular WhatsApp rather than the Business app, that's the prior step, and it isn't the same day. Registering that number on consumer WhatsApp later on will disconnect the integration.

If nobody is going to read what the agent replies during the first week, don't connect it. The value is in you approving and it executing; drop the approving half and all you've automated is the risk.

And if the primary phone is headed for a drawer: the integration drops by itself once the primary device goes roughly two weeks without activity. It's a live phone, not a server.

The reassuring part is that the exit is yours to control: from the app itself, under Settings → Account → Business Platform → Disconnect Account, the number goes back to app-only. Being able to leave without asking anyone's permission is the best sign the setup was done properly.

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If this is what you're after — your usual number, your team stepping in when it matters, and someone else absorbing the first reply, the bookings and the same four questions every day — the receptionist is built for it. Onboarding is the boring part; what matters is the week that follows.