Can I bring my WhatsApp Business API number from Twilio, 360dialog or Wazzup?
Yes, with the "Bring a number" wizard: the number, its display name, verification and approved templates come along; the old provider works until the move.
Yes. In Connections use Bring a number from another provider. The wizard runs the checks first (your business is verified with Meta, the account has room, two-step verification is off at the current provider), then Meta's own dialog where you enter the number, receive the code by SMS or call, and the number moves into a WhatsApp Business Account that you own. Your old provider keeps working until the move completes, usually a few minutes.
What comes along: the number, its display name, the Official Business Account status, the quality rating and the messaging limits, plus the approved, good-quality templates, which Meta copies without re-approval. What stays behind: the chat history at the old provider and templates that were rejected or pending.
If the number's page at your current provider has no Two-step verification tab, Meta has already retired the PIN for that number: proceed and tick the box in the wizard.