I know this is almost 9 years later, but after watching Dial M for Murder last night I found myself wondering the same thing. I knew, I just KNEW I watched this movie in black and white years ago, except the main character was NOT Grace Kelly. After a few minutes of Google searching I realized I was mixing up Dial M for Muder and Sorry, Wrong Number!!! Both movies have similar plots but different actors and Sorry, Wrong Number is definitely in black and white.