Can a business be banned only from the Calling API?

No. A ban impacts the entire WhatsApp Business Platform.

Types of Restriction:

1. Full WABA Ban (Severe Violation): If the misuse of the Calling API (e.g., repeated calls without consent, harassment) is deemed a severe violation of the Business or Commerce Policy, the entire WABA can be permanently shut down, impacting both messaging and calling.
2. Feature Restriction (Targeted): Meta reserves the right to temporarily or permanently revoke access to a specific feature, such as the Calling API, if misuse is isolated to that feature but not severe enough for a full WABA ban. This means the business could potentially lose the ability to place or receive calls via the API while still being able to send and receive messages.
3. Automatic Revocation (System): As noted in Q4, the system automatically revokes the permission to call a specific user after four consecutive unanswered Business-Initiated Calls. This isn't a ban but is a targeted restriction on your ability to call that particular user.

Conclusion: Misusing the Calling API can absolutely lead to losing the ability to use that feature, and if the behavior persists or is severe, it puts the entire WABA at risk of a complete ban.