"Is she the one who calls you?"
Translation:Is zij diegene die jou belt?
a). No, you cannot. "Wie" is not used as a relative pronoun, only as an interrogative one.
b). "wie je belt" is a subordinate clause, so the verb comes at the end.
"Is zij degene die je belt" can mean either 'Is she the one who you are calling' OR 'Is she the one who calls you'. If you want to avoid the ambiguity, you can replace "je" with either the subject pronoun "jij" or the object pronoun "jou".