You will like that it does it because the contacts that have already installed WhatsApp on their smartphones are the only ones to whom you can send free SMS to, as the app can't send free messages to non-WhatsApp users.
Ị ga-achọ na ọ na-eme ya n'ihi na kọntaktị ndị tinyeworị WhatsApp na ha smartphones bụ naanị ndị ị nwere ike izipu SMS n'efu, ka ngwa ahụ enweghị ike izipu ozi n'efu na ndị na-abụghị ndị ọrụ WhatsApp.