Should I say "in cell phone" or "on cell phone"? Can you suggest to me which one to use? How about the mobile too, "in mobile" or "on mobile"? I'm always confused about it.
You always call on phone and not in. On the other hand, you have memory in the phone where you store phone numbers, pictures etc. That is why, we call built-in memory and not built-on memory. We generally refer features of the phone as in the phone but call on the phone.
So, if you are concerned about telling someone to contact you, you say, "Contact me on my phone."