Add key to header in all page

You can't use a header with the name 'mobile'.
For a complete list of headers, see:
https://developer.mozilla.org/nl/docs/Web/HTTP/Headers

But why do you need a header to pass a value to a model?
You can include the code in the url, like this:

http://website/test/test_value/0910000000

Your controller (test) gets the value as a parameter for the function test_value:

PHP Code:

public function test_value($mobile) 
{
   //Based on the url in the example, $mobile has the value '0910000000';
} 


Or, you can assign a value to a session variable for later use:

PHP Code:

$this->session->mobile = '0910000000';
redirect('....'); 


After a redirect to another page, your controller can read the value like this:

PHP Code:

$mobile = $this->session->mobile; 


And then, you can pass this value to your model to check the corresponding data.

I cannot pase field in url because i use header key in all model that i send it from app to api
Finally i decide to use session that you suggest me
Thanks