You could have googledIf you google "representations of the Calkin algebra" which would have led, you tofind the 1967 paper of Sakai which answers your question in the negative: It says that the Calkin algebra has a type III factor representation. By the Lemma of Schur, however, every irrducible representation is a type I representation and a direct sum of more than one irreducible is not a factor.