Linking mobile phone with id is no doubt a nice idea.
What we can do is to allot a AADHAR CARD no to each phone (to prevent any duplicacy)and use NFC technology in phone.
Each phone will have its own no linked to NFC which can be used as identity.
We can further add voice sample to the identity and even walking pattern(every person has a difderent walking pattern).
The encoded information could be brodcasted to readable machines via NFC

It is a good idea to have mobile number as digital identity because penetration of mobile phone is more than landline phone.Govt. has to do some pilot study because some people may not be having the cell phone then provide them free of cost SIM with free incoming facility as prepaid connection,If in some rural family only one member is enough for a family of few member then mapping of one member unique identity is to be done with other members, person with many numbers then first number unique

Why don't you provide us a unique no like security no or personal identity number (pin) which should be verified by our adhar card no , voter id card no or pan card no which can give you all the information about the person .

Developing a device based application and user id for every citizen based on their ADHAR CARD registration.

Have an Online Application of Aadhar for mobile phones and use individual authentication to update the mobile phone numbers. The banks should be involved in the authentication process whose accounts are linked with the people. Also tele operators have to help this movement in updating all the numbers with their respective Aadhar cards and time boundly make it compulsory to update all the numbers with respective Aadhar card and bank accounts.

And Much more many usage of digital Identity for mobile phone at every step of our life in our life every thing will be most as mobile phone is most in our life we can save our data mobile no identity proof & all of our important document for daily usage.

online public services requires digital authentication which can provided through 1. robust facial recognition 2. cryptographically robust digital certificate used in bit coin. database needs highest digital security otherwise it will be national threat

Yes Using Mobile phone as a instrument we aprove our digital identity of every place any time any position.many usage of digital identity as a mobile to save our id proof on mobile and open to it any time any place.we storage our mobile phone as a laptop as computer and our file system.

I doubt that if we take device id as one of the unique parameter ,after factory resetting or changing the device it would not point to the same id.

Easier Internet access is essential first. Making that faster and cheaper in the existing condition will help enabling digital identity. Other than that voice recognition can be used to verify the digital identity