KOLKATA: India’s largest ever spectrum auction kicks off today with over 2300 Mhz of airwaves on sale at a total reserve price of Rs 5.60 lakh crore.The coveted 700 Mhz (4G) band will be offered for the first time but starting prices are high.No. 1 telco Bharti Airtel and newcomer Reliance Jio Infocomm could spend $1 billion each to augment data capacity. Vodafone India and Idea Cellular , which need to boost 4G holdings, could bid twice that, said Goldman Sachs.Jio’s Rs 6,500 crore deposit is a clear signal that it means business, analysts said. ET looks at what companies want and why.