In the sentence
Whom is she calling?
what type of object is whom?
Is whom an indirect object because she is doing the calling to a person referred to as whom?
In the sentence
Whom is she calling?
what type of object is whom?
Is whom an indirect object because she is doing the calling to a person referred to as whom?
"Whom is she calling?" has only one object and so it is the direct object.
Normally the ditransitive verbs like give, grant, tell etc. take two objects (direct and indirect object).
The verb 'call' is not a ditransitive verb except maybe in the idiomatic expression 'call names' meaning 'verbally abuse someone' (example: He was calling me names because he disagreed with something I'd written).
Direct objects normally answer the question what? and indirect objects answer the question (to/for) whom?
Examples:
His father gave John enough money to buy a bike. ((to)whom? - John = Indirect Object; what? - money = Direct Object)
'Whom is she calling?' is incorrect. That should be 'Who is she calling ?', or 'To whom / with whom is she speaking?' Whom is the residue of a dative case for nouns/pronouns, in older, more inflected versions of the english language