Holding a phone to ear or hunching between neck/shoulder are bad practice relating to RSI issues. It clamps down /crowds the area where many nerves & blood flow have to squeeze thru..
Can you get some sort of headset?
Upper body posture is important, take breaks , do opposite stretches , be aware of shoulders rolled/hunched or head forward..
Check the sticky threads more much more detailed info & links
http://neurotalk.psychcentral.com/thread22626.html