Modern technology has facilitated many things in human life, including the subject of buying and selling online, especially buying and selling over the mobile phone, and the spread of this type of sales through mobile technology. Unfortunately, many people are in legal prohibitions, Gharar, cheating, etc. Therefore, legal scholars must study and examine them in some detail. From this point of view, the researcher discusses the opinion of the scholars and the shar'i rulings so that the Muslim is fully aware of the provisions of this modern method. And be aware in his dealings with others.