'Sorry, Wrong Number' is a suspenseful noir film from 1948. The movie centers around a bedridden woman who overhears a murder plot on a crossed telephone line and is desperate to prevent it.
Barbara Stanwyck, bedridden, overhears a murder plot on a crossed line and spends the next 89 minutes trying to convince anyone, anyone, that it is hers. The original phone-based thriller. Every later entry on this list is in its debt.
Innovative phone call narrative structure, inducing suspense and paranoia.