I have heard of some people using phone shoulder rests, they have been around for years. They are basically phone assessories that attaches or rests your phone on your shoulder, and you can talk and listen with out using hands. They come in all different materials including soft Gel cushioned, and are suited for all different sizes, brands and shapes of phones.
Someone I knew used a speak and dial voice activated phone, once you pick up the reciever, the phone does the rest of the work for you. It really does make a difference, no more strain on the neck, shoulder or hands.
There are other ideas out there, such as phones with jumbo key pads and phones with louder / clearer speaker phones.