Answered on February 02,2019
Registering Mobile Number with Aadhar
Registering a mobile number with Aadhaar is not mandatory. However, if you want to update your Aadhaar details online, you need to have a mobile number registered with your Aadhaar. The website sends an OTP to the registered mobile number to authenticate your identity before allowing your request for Aadhaar updation. Registration of mobile number with Aadhaar is only for the purpose of authentication.
If you have not registered your mobile number at the time of enrollment, you need to visit nearest Aadhar enrollment centre to register mobile number with Aadhaar Card. It cannot be done online as you need to provide biometric details.
Linking mobile number with Aadhar
Mobile number provided at the time of Aadhar registration is used only for authentication purpose and that mobile number may not be your number. It can be that of relatives or friends number. The primary purpose of linking aadhar to mobile number is to uniquely identify that you are the legitimate owner of the SIM being used. Linking establishes the identity of a mobile number owner. For this purpose, your biometric is also taken.