Coupling

The fact that Jane seems to be able to freely enter wherever she wishes, whenever she wishes is referenced by Steve's line about their life not being "an American sitcom." It is true that many American sitcoms have an overabundance of unlocked doors, where anyone can waltz in and start speaking to the characters at work, but mostly at home. It could also be an in-joke to the fact that Coupling inspired a short lived American sitcom of the same name. Jane also keeps the keys to all of her ex's flats, hinting that she and Patrick may have had more than just a one-night stand.

The Dalek prop is a reference to Dr. Who, the classic British science fiction series and perfect for Oliver's comic book/ collectibles store.

Patrick's dream/fantasy is a direct 'steal' of the television show The Prisoner.

The title makes reference to the characters being on the phone at night, but also to the lines of communication that are opened- for good and ill- during those night-time calls.