Bharti Airtel Ltd, India`s largest phone company, will spend Rs.3,500 crore to acquire fourth-generation (4G) spectrum from Aircel Ltd in Tamil Nadu (including Chennai), Bihar, Jammu and Kashmir, West Bengal, Assam, the North-East, Andhra Pradesh, and Odisha telecom zones as it prepares for a high-stakes battle with Reliance Jio Infocomm Ltd.