If mobile phone is not allow in NDA hostel then how can i contact to my parents or other friends ? How is it possible?

Yes, mobiles phones and other electronic items like laptop, DVD player, pendriveare etc not allowed in NDA campus. There is a seperate arrangement of calling for all candidates where calling is allowed according to rules of time by cadets. But many senior cadets sneak them in.

Mobile phones are strictly prohibited inside the campus and checking is done on weekly basis and if you caught by checking officer then you have to face the consequences means harsh punishment of undiscipline.

For more information you can check on official brochure here

http://www.google.com/url?sa=t&source=web&rct=j&url=http://joinindianarmy.nic.in/writereaddata/Portal/Images/pdf/JI_141_C.pdf&ved=2ahUKEwjn69urtbjiAhUg7XMBHeI6DxQQFjAKegQIBhAB&usg=AOvVaw3r0-DTPKWx4QR9Lcl02xYr

Best of luck