All.... I got the solution...
The solution though appears to be weird, but it worked for me.
The problem analysis:
I upgraded my phone to ios 10 with face time activated and sim inserted in it, the information data related to sim ID seems to get corrupted with the upgrade and hence every time I restart it tries to activate and activate as well but not able to save the activation information.
Solution:
I tried another sim card and that worked in without the problem, hence i asked my operator to replace my Sim card and since the sim will come with new sim id the problem resolved for me.