Embedded Signup: connect your WhatsApp number without leaving the site

Embedded Signup is Meta's official flow for connecting a WhatsApp number to the Cloud API without leaving the platform's website. Everything happens in a Meta-hosted pop-up: you sign in with your Facebook Business account, pick or create the business, pick or register the number, and come back with the connection done.

Why it matters

Before embedded signup, connecting a number meant creating apps in Meta's dashboard, generating access tokens and sending them to the vendor — usually by e-mail or chat. Slow, and unsafe: a system token travelling outside any vault.

In the embedded flow the authorisation is issued by Meta and delivered straight to the platform's server. You never see or copy a token, and the granted access can be revoked at any time in Business Manager.

What happens at each step

1. Sign in and pick the business — you use the account that administers the company in Meta Business Manager, or create one on the spot.
2. WhatsApp Business Account — the WABA that will hold your numbers, templates and quality rating. It is created in your company's name.
3. Number — register a new one (verified by SMS or call) or migrate an existing one.
4. Confirmation — the window closes and the platform finishes up: it resolves the WABA, subscribes the webhooks that deliver messages, and registers the number on the Cloud API.

After that the inbox starts receiving. If somebody writes to the number, the message shows up in realtime.

Coexistence: keeping the phone app

If the number is already used in the WhatsApp Business app, there is an alternative to a plain migration: coexistence mode. You scan a QR code inside the official flow and the number then works in both places — the app stays on the team's phone and the same conversations appear in the platform.

One technical difference matters: coexistence numbers do not go through Cloud API registration, because the app linkage already covers it. If something asks you to "register" a coexistence number, the configuration is wrong.

Common errors and what to do

"This number is already in use" — the number is active on regular WhatsApp or in the Business app and has to be freed first. Deleting the account inside the app frees it within minutes; or use coexistence, which requires deleting nothing.

The window does not open — the browser blocked the pop-up. The click must come from a direct user action; if a blocker caught it, allow the domain and try again.

"Could not complete the connection" — usually the business is not verified in Business Manager yet, or the signed-in person is not an admin of it. Business verification is a Meta process and takes hours to a few days.

No messages arrive after connecting — the webhooks were not subscribed, or the number was not registered. Reconnecting through the same flow fixes most cases.

After connecting

With the number live, the usual next steps are creating the first templates, inviting the team with roles and, if it fits, granting access to an AI agent. Before that, it pays to understand the 24-hour window — it decides what can be sent, and when.