Hello Nandini, smart phones Is need of today's world. And now various apps and study material is now available on mobile. So mostly all colleges are allowing cell phones to students. IIT and NiT also encouraging students to use mobile phones in campus. Even if they shares assignments or any study material via mobile. So you can use mobile in campus of IIT and Also inn NIT. But you remember that you should not disturb class due to your mobile. 

I hope it will help.

Thanks.