Asking a person's name in different forms

Question

Are these grammatically correct?

1. Vous êtes Philippe ?
2. Est-ce que vous êtes Philippe ?
3. Il est Philippe ?
4. C'est Philippe ?

Answer 1

All but the third one are correct French, but none of them is asking a person's name.

1 and 2 are asking someone if he is Philippe (and not someone else). (Are you Philippe?) Alternatives are C'est vous, Philippe ?

4 is asking someone if someone else is Philippe. (Is he Philippe?)

To ask someone if his name is Philippe, you might say:

(Est-ce que) vous vous appelez Philippe ?

C'est Philippe, votre prénom ?

and to a third person:

(Est-ce qu') il s'appelle Philippe ?

Note that Il est Philippe ? is a typical non native speaker mistake. You can say Il est Français or il est médecin but that doesn't work with a first name.

Answer 2

The first two are used if you are asking the person directly. The third is mainly used if you are asking someone else about Philippe, but it is more or less not the best formulation. The fourth could be used in both cases.

Two more ways could be used if you are talking to Philippe directly.

Etes-vous Philippe?

Or in an inquisitive tone:

Monsieur Philippe?