Actually, WhatsApp or any blank Message are unsupported messages which do not show anything inside the message body and look empty. Actually, SMS which is Short Message Service would never be sent empty or blank. SMS always contains a minimum of one character. Some Characters of another language which are doesn't show on the mobile screens but are still sent to other Mobile. He also gets message but nothing is written Blank Message. Simply when people send those types of characters to any person, he or she does not see them and thinks the message is empty.