Can I use the same number for Sinch's WhatsApp service and a regular WhatsApp account?

No. The process of binding (associating) the number to Sinch's WhatsApp service blocks that number being used to register a regular WhatsApp account.

Similarly, if a number is already bound to a regular WhatsApp account, it cannot be used with Sinch's WhatsApp service.

Learn more about the Sinch WhatsApp Business API.