Using whatsapp messaging to notify users when their order is ready

i'm designing a food ordering experience for a restaurant and we're considering using whatsapp business as a way to notify users when their food is ready. this means users will input their phone number at the cart screen of the app. has anyone here used whatsapp business version and could recommend if this is good way or if there are better methods to notify the user when their food is ready? e.g. push notification