The country's second-largest mobile operator said testing of 4G services has commenced successfully and it has partnered with leading global technology infrastructure service providers for the network rollout."Vodafone India confirms that it will launch its 4G services by the end of the calendar year 2015. Important data markets, including Mumbai, Delhi, Kolkata, Bengaluru and Kochi, will be part of the first wave of the rollout," the company said in a statement.