How to determine Phone Model on http-server

[Mr.Y]

I have a script on my http-server, that determines the model of the phone that sends http-requests (POST, for example). I need it to determine what to answer (the answer has to depend on the phone model)
For many years i have been using User-Agent field to solve my task. I know that user-agent can be redetermine in general (by network provider for example).
My question is: "How to determine the http-request sender's phone model without user-agent"?

[wizard_hu_]

I know that user-agent can be redetermine in general (by network provider for example).

HTTPS could be a workaround for the case when a 3rd party would modify the header.

My question is: "How to determine the http-request sender's phone model without user-agent"?

Not really, HTTP is not invented for providing reliable identification of anything.