With essere the sentence means the action is done to her. Avere (avrà chiamato) would mean she was doing the calling.
I'm pretty sure it has to have an object. Mi avrà chiamato should work for "She will have called me." To make this intransitive, I think you have to use telefonare. Sarà telefonata. (Which might also mean "It will be telephoned.")
If the verb has avere in the perfect (its transitive) then essere turning up means its passive. If the verb has essere in the perfect (its intransitive) then its the future perfect "will have" stuff.
If the verb is like passare that can be either transitive or intransitive then I get stuck :-(