Mukesh Ambani on Thursday broke open the widely-awaited details of his Reliance Jio venture, billed as the country's largest 4G network. Reliance Jio will not charge for voice calls or for roaming calls within India. Customers should be charged for voice or data, but not both, said Ambani. Reliance Jio's data prices are roughly one-fifth of what customers have been charged so far - one gigabyte of data will cost Rs 50.