I thought you will be offering this free service but you are charging 5 dollars for it. How can we be sure that the number we get is not used one for whatsapp and other popular services already, It will be good if your can share success stories or feedback from clients.
Quite expensive compared to the service i have used in the past.
https://smspva.com for example just charge $0.2 or $0.5 for phone number verification. I have used them in the past to verify a couple of gmails... Not used them for Whatsapp thou