The phrase "inch smartphone" refers to the size of the phone's screen. It means that the display of the smartphone measures a certain number of inches diagonally.
Sentences with «inch smartphone»
And it's also still a 5.99 - inch smartphone with very minimal bezels — no notch and only a chin. (androidheadlines.com)
You can have this 5.5 - inch smartphone for cheaper, and it has almost everything you need. (techradar.com)
The Mate 8 is a 6 - inch smartphone running Android 6.0 Marshmallow, though you wouldn't know it at first glance. (theverge.com)