Bharti Airtel has appointed Manish Tiwari as global chief ­information security officer (CISO) and senior vice-president (VP). Tiwari joins Airtel from Microsoft India, where he was the company’s key external strategist, spokesperson and ­cybersecurity adviser on all aspects of IT risk management and information assurance. Tiwari replaces Siva Sivasubramanian, who has rejoined Australia-based telecom company Singtel Optus as its CISO. Sivasubramanian worked at Singtel Optus for almost 11 years before moving to Bharti Airtel in mid-2014.