A shared WhatsApp inbox for a small team, and where AI fits

• The WhatsApp Business app with linked devices. WhatsApp’s Help Center says you can use “up to four linked devices and one phone at a time”, and linked devices log out if the phone goes unused for more than 14 days (WhatsApp, linked devices). With multi-agent, part of a Meta Verified or Meta One subscription, you can link up to 10 devices depending on your plan, assign chats and see which agent sent each message. WhatsApp notes it may not be available to you yet (WhatsApp, multi-agent).
• The WhatsApp Business Platform (the API) with an inbox tool. Your number connects to Meta’s Cloud API through a provider, and the team works in a web inbox with personal logins. Assignment, roles and notes come from the tool, not from WhatsApp.
• A custom inbox. The same API, with the inbox built around how you work and connected to your customer record, bookings or orders. It fits when the inbox needs data from elsewhere or your rules are unusual.

The app works for two or three people who can all see every chat. The Help Center describes assigning chats and filtering by “Assigned to you”, not hiding chats from a device, and a filter is not a permission. If a new hire should see only their own chats while the manager sees all, you need the API and an inbox with roles.

The 24-hour window. When a customer messages or calls you, a 24-hour customer service window opens and you can reply freely. When it closes, Meta says “you can only send pre-approved template messages” (Meta, send messages). So a customer silent for two days gets a template first.

The customer who called and you missed. A WhatsApp call to your number on the API opens that window too. A call to your landline or mobile does not, and having their number is not enough: WhatsApp’s Business Messaging Policy (last updated 23 September 2026) lets you contact people only when they gave you their number and you received their opt-in to receive messages from you (WhatsApp Business Messaging Policy). Ask on the phone whether you may follow up on WhatsApp, note the yes, and start with a template.

Groups. Groups created in the phone app do not come into an API inbox. Meta’s Groups API is only for Official Business Accounts, allows up to 8 participants, works by invite link, and “Groups are not available for WhatsApp Business app phone numbers” (Meta, Groups API). Tools that promise to pull your existing groups in usually rely on unofficial connections. WhatsApp’s terms forbid using the service in unauthorised ways, by automated or other means, including making it available to multiple devices outside the tools WhatsApp provides, and let WhatsApp disable or suspend the account (WhatsApp Terms of Service, effective 17 August 2026). We do not use them: the number is what you would risk.

Keeping the phone app (coexistence). Two businesses we spoke to assumed this was impossible. It is not: from app version 2.24.17, a Meta partner can connect your WhatsApp Business app number to the Cloud API while you keep the app. Messages are mirrored both ways, and contacts and up to six months of one-to-one chats can be synced within 24 hours of onboarding. What changes: group chats are not synced, broadcast lists become read-only, disappearing and view-once messages and live location are switched off in one-to-one chats, and calls stay in the app. Linked devices are logged out at onboarding and have to be linked again, and the app’s quick replies, labels and away messages are not available through the API. Messages sent from the app stay free (Meta, onboard WhatsApp Business app users). In version 5 of Embedded Signup, the sign-up flow partners use, released on 20 October 2026, this onboarding is on by default (Meta, Embedded Signup versions).

Photos and documents. The API carries images, video, audio, documents (up to 100 MB) and stickers. A file a customer sends can be downloaded through the API for 7 days (Meta, media), so the inbox has to save its own copy.

Ask any inbox, bought or built:

1. Assignment. Can each chat have a named owner and be reassigned in one step?
2. Restricted views. Can a new hire see only their own chats?
3. Internal notes. Can the team leave notes on a chat that the customer never sees?
4. Handover. When someone is off, do their chats move to a colleague with the history?
5. When someone leaves. Does their access close while the history stays with the business?
6. Who owns the number. The WhatsApp account should sit in your own business portfolio. Meta says businesses onboarded through Embedded Signup “own all of their WhatsApp assets” and have full access to WhatsApp Manager (Meta, Embedded Signup).
7. Export. Can you take conversations and contacts with you if you leave?

• The inbox. Off-the-shelf tools charge monthly, often per user, so the bill grows with the team. A custom inbox costs more up front and nothing per head; which wins depends on team size and time.
• Meta’s messages. Meta charges per delivered message and does not charge for messages customers send you. Since 1 October 2026 your replies inside the 24-hour window are charged too, after 1,000 free a month per number (Meta, pricing). The sums are in WhatsApp service message pricing in 2026.
• AI, if you add it. The model cost of each message the agent writes, and someone to keep its rules current; see what you keep paying for after an AI agent goes live.

One change to plan for: on 21 October 2026 Meta announced that marketing messages sent through the Cloud API end on 13 October 2027 and move to the Marketing Messages API (Meta for Developers). If you plan promotions from the inbox, ask your provider about the move; the announcement does not mention customer service replies.

Several teams we spoke to want the inbox now and AI later, and we think that is the right order. A month in a shared inbox shows who answers what, how fast, and which questions repeat: exactly what an AI agent needs.

The agent then joins the same inbox as one more member of the team. It drafts replies for a person to approve, or answers the repeated questions itself; hands the conversation, with its history, to a named person when a case needs judgement; and logs every question it could not answer, so you know what to add. WhatsApp’s policy requires automated replies to come with “prompt, clear, and direct escalation paths”, such as a transfer to a person in the chat. Whether AI is allowed at all: see is AI allowed on WhatsApp Business?

1. Count who answers, then choose the app (four linked devices, 10 with multi-agent) or the API with an inbox.
2. On the API, decide whether to keep the phone app (coexistence).
3. Move customer conversations out of groups, or accept that groups stay in the app.
4. Collect opt-in for follow-ups and get your first templates approved.
5. Confirm the WhatsApp account is in your own business portfolio.
6. Run it for a month, then pick the questions for an AI agent.

New to the API? Start with what the WhatsApp Business API is, and when you need it.

When we set up a WhatsApp AI agent, the inbox comes first: your own number on Meta’s official API, named people and handover rules, with the agent inside the same inbox. See our WhatsApp customer service AI agent.