If your phone was caught during the arrear lab exam in Anna University, it is considered as malpractice. In such cases, the university can cancel your exam and may even cancel all the exams of that semester. They may also charge a fine or debar you from appearing in exams for some time. You will be called for an inquiry, and after that, the final decision will be given. It’s important to follow the university rules and respond properly to any notice they send.