After repeated delays, Reliance Jio has finally launched its hugely anticipated offering of free voice calls over its 4G-only network in India. The interruptions temporarily gifted other players some breathing space, but this aggressive move to shift the Indian market towards data-only mobile plans will throw up some real problems for incumbent telco Bharti Airtel and second-placed Vodafone India, which both still pull in the majority of profits from voice and text. Jio is clearly aiming, after all the years of tortuous network building, and recent disputes with the regulator, to be as disruptive as Iliad Free was in France or T-Mobile USA was with its ‘Uncarrier’ launch – which Jio’s resembles. For the first time in India, free voice…