I'm glad you are at least finding out what is happening.
Can you get an iPad? This may help reduce the strain by having a slightly bigger screen.
Also, think about how you can break up your time on the phone, even taking a 10 minute break after an hour can make a difference.
Apply drops if they feel dry, then close your eyes for 5 minutes.
Then spend 5 minutes focusing on something further away - looking out a window works. As suggested above too, at this time do some eye exercises, looking up, down, left, right, with your eyeballs only.
Get glasses that have glare protection too.
Hopefully the glasses will make heaps of difference, I know I've been there, putting off my next eye check too long, then complaining my eyes are dry and scratchy. doh!