Quite often headaches are caused due to lack of circulation to the head - if this is the case, you might want to try taking cayenne pepper, either in tincture form, mixed with water or juice - or in capsules, to help increase circulation. I would also use some type of cayenne ointment on my neck and at the base of the skull to help relax the muscles and increase circulation - it can also be applied to the temples - just be careful to not get it in the eyes.
If you are using a cell phone that often - you should probably get an ear piece or start using the speaker phone, so that the phone is not directly against your head.