mobile.ts

type ConfirmedMobile = string & { __random_transparent_property: never }
type UnconfirmedMobile = string & { __another_random_transparent_property: never }
type CertifiedMobile = string & { __again_random_transparent_property: never }
type Mobile =  // ConfirmedMobile | UnconfirmedMobile | CertifiedMobile :)
    ConfirmedMobile 
    | UnconfirmedMobile 
    | CertifiedMobile

const printString = (p: string) => console.log(`print String ${p}`)
const printConfirmedMobile = (p: ConfirmedMobile) => console.log(`print ConfirmedMobile ${p}`)

printString('foo') 
// ^^^ ok
printConfirmedMobile('foo') 
// ^^^ compilation error: cannot assign 'foo' to type ConfirmedMobile