"Is it legal to do small range jammer for mobiles?"

I guess the answer is a big NO for any non-government agency to do one such. And even with the government it is purely on security issues.

This is as much as I read in a newspaper clipping when they reported the failed assasination attempt on a state head. The jammer saved the day for the President.I would not be able to verify the veracity of the statement though.

Raghu