Hey, I'm an apprentice electrician and was asked to do some phone work. I found the problem and fixed this by replacing an old phone receptacle. But when I changed it the wires weren't red, green, black, and yellow coming in it was black red and white. The black was on the green and the red on the red but the white was just connected to the receptacle. (It was a one line receptacle)So in the new receptacle I put the black on the green and the red on the red but I also put the white under the white screw. I just want to know what the white was doing in the receptacle and if it's going to do any harm where I connected it. The line seems to work fine but I can't find out what that white was for anywhere.

Thanks in advance