Yellow is more than just a color. It can also be a greeting. I’ve called more than one friend who answered the phone, “Y’ello!”
I found this vintage candlestick telephone in my basement a few months ago. It probably pre-dates “Y’ello”-–

I’m not sure I have all the pieces of this telephone, but these were the basics. It looks so alive — like something Pixar could love. “Luxo Jr” might like to come over to play.
It’s originally from my father’s service station. It was his business phone in my early childhood, and was a relic even then. If you wanted to make a call, you picked up the receiver (or turned the crank? — it’s so long ago I’ve forgotten) and said something like “Hello Bernice, please connect me to the drugstore,” or perhaps the shorter, “Drugstore, please.”
The cabinet it once stood on is in my breakfast room now, holding dishes. It still has the little shelf he tacked onto the side to hold the phone.

Candlestick phone detail: long before phones evolved to be smart. Too bad it’s suffered some damage.
But back to Yellow. I can’t find any agreement on who first answered the phone with a color. Some say Homer Simpson, but I remember at least one friend who answered that way at least a decade before Homer was invented. Here’s one thing I did find:
On March 10 1876, Alexander Graham Bell made the now-famous first telephone call. “Mr. Watson — come here — I want to see you,” he said. Too bad there’s no mention of whether Mr. Thomas Watson said, ‘Y’ello?’ when he picked up.
Tell me — how do you answer the phone?
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For more on the Weekly Photo Challenge: Yellow
and, a concession to the intended subject —