Is there any way to communicate in an emergency when there is no cellphone reception?

My son, who is constructing roads in southern Missouri where there are lots of big hills and deep valleys, just cut his leg while cutting down trees with a chain saw. There is no cellphone service there. He was very fortunate and able to walk a mile or so to his closest neighbor’s, who rushed him to the hospital. Do any of you have any suggestions about how he could communicate with someone in case of another accident when there is no cell phone coverage for miles?