You will create a WhatsApp Business API account when you submit a 360dialog signup form. If you already have a 360 Client Hub account you can submit multiple phone numbers to a same WABA by following these steps.
How to find the WhatsApp Business Account ID
The WhatsApp Business Account ID (or WABA ID) is shown in the WhatsApp Accounts page:
A Phone Number always needs to be associated to a WhatsApp Account so this accounts can send and receive messages.
For WhatsApp Business API accounts, this number needs to be registered and verified during the signup process with the BSP. If you already have a 360 Client Hub account you can submit multiple phone numbers to a same WABA by following these steps.
A single WABA can contain up to 25 different phone numbers. This limit can be expanded to 120 numbers on request. Within your company, you may have separate WABAs for different divisions. You can have unlimited WABAs under a business manager.
How to manage phone numbers
If you created your account via Embedded Signup, you can see the phone numbers that are registered under a specific WhatsApp Account directly from your Business Manager:
In this page, you will be able to see the status of this number.
To add a new phone number in a WhatsApp Business API account, please do not use the Meta Business Manager. This setup will not work. A new WhatsApp Business API number should always be added from the 360 Client Hub dashboard.