India's largest mobile phone company, Bharti Airtel, said its net profit in the most recent quarter rose 73 per cent from a year ago, despite growing competition and a decline in tariff rates.Improved margins and a record addition of subscribers helped Bharti Airtel post a profit of Rs 16.14 billion in the July-September quarter, up from Rs 9.34 billion last year, Chief Executive Officer Manoj Kohli said.