Use a telephone headset
Be careful not to hold your phone between your ear and shoulder. A hands-free device is a great way to talk on the phone without being tempted to hold your phone incorrectly.
Exercise your neck muscles. Keep your neck muscles strong by doing strengthening and stretching exercises frequently throughout the day. One of the simplest exercises to do often is the chin tuck exercise. This exercise helps strengthen the muscles that pull the head into alignment over the shoulders. It also stretches the scalene and sub-occipital muscles.