Bonjour William and Chris !
Chris, you are indeed mistaken here: appeler takes a direct object in French:
Tu appelles quelqu'un.
As for your question William, your confusion comes from the difference between appeler [quelqu'un] (to call [someone]), and the reflexive s'appeler (to be called / literally:"to call oneself").
In the first case, you'll use tu appelles (you call)
-> the subject pronoun tu never contracts into t' in written form (though you might have heard it in speech).
In the second case, you will use tu t'appelles (your name is)
-> t' is the contraction of the reflexive pronoun te
I hope that's helpful!
À bientôt !
