I was a user of Tata Docomo service. But I am regraded to say that their service is very poor.
Tata docomo network could not reach distant area like nearby forest area and sea beaches like Puri ( urissa) .
Secondly their customer care service is also very bad.as you cannot talk directly with a exicutive.
3rd the network is very slow! Specially the internet speed is very low.
Their roaming charges are higher than other networks.
For these reasons I rejected the Tata Docomo sim and now I am a jio user.