Phone number requirements
Your number must be able to receive a one-time code by SMS or voice call, and it should be a number your business controls for the long term.
Can I use my existing WhatsApp number?
Often yes. An existing number can be moved to the WhatsApp Business API if it meets the requirements and is not active on the consumer WhatsApp app at the time of migration. Moving a number is a one-way step, so plan it carefully.
OTP verification
During setup, Meta sends a one-time code to the number by SMS or voice call. You enter that code to confirm you control the number. If the code does not arrive, check that the number can receive external SMS or calls and try the voice option.
Number ownership
The number should belong to the business, not to an individual employee. Using a personal number risks losing access if that person leaves, and can complicate quality and template ownership.
Common setup mistakes
Reconnecting or changing a number
You can change or reconnect a number later, but it may affect your customers, templates, quality rating and setup. Treat a number change as a planned migration, not a quick edit.
Why Mersal warns you before you change numbers
When you connect another number or disconnect one, Mersal shows a warning. WhatsApp counts the last 30 days of conversations separately for each business number, so a new number starts with no history. Customers who aren’t in your WhatsApp contact book may appear without their phone number on the new number. See “Changing your WhatsApp number and your Meta contact book”.