Bells Are Ringing (1960)

Ella Peterson works in the basement office of Susanswerphone, a telephone answering service. She listens in on others' lives and adds some interest to her own humdrum existence by adopting different identities for her clients. They include an out-of-work Method actor, a dentist with musical yearnings, and in particular playwright Jeffrey Moss, who is suffering from writer's block and desperately needs a muse.