It was set in present-day 1950. Bogey drove a 1949 or 50 Mercury convertible. The apartment complex had a hacienda theme and the phones and decor could have been used to make it look lived-in and pre-war. It's hard to know what they were thinking in 1950. Other places had 202s or Kellogg Redbars. I don't want to give away the ending, but the phone plays a prominent part in how the movie turns out.
Christian, you have a really good eye. Yes, those phones were painted some color. I don't know what color because it was in black and white, but when I looked at some of the movie last night it was plainly obvious that the phones were painted a dark. matte color. The handsets and housings were very dull.
I first thought from the picture that maybe the phones were sprayed with a non-glare coating so they didn't reflect the studio lights, but it was more than that. They were something like dark green or dark red or maybe brown. Like Christian says, they were lighter than the black items like Bogey's suit (in another scene) or Nick Ray's shirt.
