Chart above is from a Western Electric catalog. It doesn't include all Western Electric colors, or all of the colors made by other phone manufacturers.
Some phone colors -- such as black, white, ivory, light blue, green and beige -- were identical, whether made by Western Electric (ATT), Cortelco (ITT), Comdial (Stromberg-Carlson), or Northern Telecom (Nortel).
The red phones from ATT are darker than most red phones from the other companies.
Some red phones are described as "cherry red." Cherries come in different colors, so we say "dark red" and "bright red."
Older red phones from Northern Telecom are dark like ATT. Newer ones are bright red.
Most ATT yellow phones are lighter than the harvest gold used by other companies, but some are just as dark.
Northern Telecom originally used the same yellow as ATT, and later switched to harvest gold.
ATT "Design Line" phones were made in some colors not used for standard phones.
Some standard styles were made in unusual colors, such as teal blue, for just a few years.
ATT didn't make ash-colored phones, which were big sellers for the other phone makers.
Northern Telecom called ash "chameleon" or "chameleon gray" because it seemed to blend in anywhere.
Ash (or chameleon) is a light warm gray, like the color of a cigarette ash, or many PCs of the 1980s and 90s.
Some ITT phone boxes were labeled "ash-almond" in the 1980s because almond was a popular appliance color, and most people outside the phone business did not understand what "ash" was.
Phone color can change over the years, due to cigarette smoke, strong light, and airborne chemicals. Light blue may look like turquoise. White may look like yellow. Ivory may look like beige. Sometimes different parts of the same phone may have different color shifts.