Telephone Novels

This is somewhat related to my last post about novels written on Twitter, with mention of Japanese novels written on cell phones (the ones I've seen are pretty fragmentary), however this post concerns novels that are comprised entirely of a phone conversation, and are wholly dialog. Thus far it's a short list, though I'd love to hear of more. I've always been attracted to films that are largely dialog (My Dinner with Andre and Twelve Angry Men come to mind) as well as stories like Hemingway's The Killers or even A Clean Well-Lighted Place. There is something about sheer dialog holding its own without the props of background (or foreground) action that intrigues and satisfies me.
I'm currently reading Nicholson Baker's Vox which consists entirely of a conversation between two people who dialed up a phone-sex matchmaking service. I haven't finished the book, but the confessional nature (two people sitting/lying in the dark talking to a stranger) is compelling, and not nearly as sexual as one might expect. Although the man (anonymity is valued after all) is strangely aroused by Tinkerbell. Anyway, the only other novel that I've read or heard of, that takes place entirely as a phone conversation is Interviewing Matisse, or The Man Who Died Standing Up by Lily Tuck, and it was probably the most infuriating novel I've ever read outside of Creeley's The Island. This novel consists of two women talking past each other for around 140 pages. I couldn't wait to finish it, yet couldn't put it down for fear something might happen. It reminded me of watching Warhol's Sleep in Chicago many years ago, and how there were many comments about not leaving for fear of missing something important. Turns out the most important action was John Giorno rolling over. With regard to telephone novels, I'm sure that William Gaddis would have written one had he thought of it, although his would involve a switchboard.