One year after storming into India's mobile phone market with free data and voice services, billionaire Mukesh Ambani's telecom unit is gaining momentum against its bigger rivals via a regulatory decision to lower interconnection fees. The reductions that begin Oct. 1 will probably bolster Reliance Jio Infocomm Ltd.'s earnings by 76 percent in the year ending March 2019, Morgan Stanley analysts Parag Gupta and Amruta Pabalkar estimate.