手机

Chinese has special measure words for many nouns, but 个 is the default that works almost everywhere. With phones, textbooks prefer 部 because it sounds more precise. In daily conversation, people say 一个手机 all the time. The story uses 一个手机 because the narrator is speaking casually. “在北京的一个商店，我买了一个手机。” (At a store in Beijing, I bought a phone.) ── [《苹果十五》](/read/buying-iphone-beijing#s1)

English 'phone' covers everything: the device, the number, the call. Chinese splits these. 手机 is your mobile device. 电话 is a phone call or a landline. If you want someone's number, ask for 手机号 or 电话号码. Saying 你的手机是多少 sounds like you're asking for the physical phone's price or size.

Think of your phone as a box. Apps, photos, and WeChat wallet money are stored inside the box, so you use 里. If something is resting on the glass surface, like a scratch or a sticker, use 上. English says 'on my phone' for both, which is why learners mix them up.

If you're bored and scrolling through videos, that's 玩手机. If you're using your phone to pay, navigate, or work, that's 用手机. Both are correct, but they describe different activities. English 'I'm on my phone' can mean either one, so context decides.