I took the picture to demonstrate why you won't catch my heroine texting her friends or searching for her phone in her pocket. She and her classmates would never get in trouble for bringing phones to school, because that would entail ripping large wooden boxes off walls or sneaking in candlestick telephones that are far from being wireless.
One of the advantages of writing historical fiction set in the fairly recent past—as opposed to say the Middle Ages—is that I often stumble upon items like this phone in everyday places, and I can explore how these contraptions look and feel. Here's another historical device that appears in the novel...found in my good friend's Victorian home she's renting:
Although it looks like elevator controls, it's actually a push-button light switch from the late 1800s. My characters wouldn't be flipping on light switches like we do in modern homes, so I always need to make sure I phrase things the right way when writing scenes involving the technology of the day.
I'm still not sharing the names of these characters who are talking into giant, boxy wall telephones and pushing light-switch buttons. You'll need to wait until I post the official synopsis before learning more about this WWI-era protagonist of mine and the ghost in her life. For now, I'll just leave these little breadcrumbs of information about the novel's historical world. The bigger and better revelations are yet to come...