Both the HO and N scale layouts have a computer attached and a wireless gadget and the software called JMRI so that you can drive your trains with a mobile phone.
Even George has gotten into it with the purchase the other day of a mobile phone from Big W I think it was, for a princely sum of 30 bucks.
You ask “Why not use my current one?” Well, you can. But I find that if I run the battery flat while driving trains, then I have a problem. Many figure it is easier to just get a phone (no plan or SIM Card required) and use it as a dedicated throttle and I agree.
So as long as it is an Apple phone or a fairly current Android type phone with a roughly 4” screen, then you will be good to go. There are a few at the club who can set it up for you once you have it. Me, I have a preference for Android type phones since they have software called lovely things like Lollipop and Marshmallow and such.