Jio sim, it is sim launched by reliance company, it is free sim in India with 4g data . The reliance is providing us 6 months of free 4g internet, free calling and free chat or messaging with friend. When they launched the jio sim, it was the fastest 4g sim in India, it speed is fantastic among all sim but after reliance told that jio sim is for all 4g mobile phone, the Indian people buyed it and then the speed of the jio sim is reducing day by day. In some places it work perfectly, but in some area it is very slow. But now also it is a fastest 4g sim in India. So go and buy the sim and enjoy the speed of real 4g. Thank you