if you are linking it for the first time,must go to enrollment centre to get the mobile update.firstly fill the aadhar update form along with photocopy of aadhar card mentioning only mobile to update.
if you are to update or change the mobile number , can be done online.but exiting number linked to aadhar, is functioning.This because OTP is sent to authenticate the updation.then the new number can be updateed.
