Satellite communications.

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As long as bidirectional voice communication is not required satellite
communication is about as good a medium as there is. 
Amateur radio is another but it requires a skilled operator at each end.
Marine VHF is a mode that should be explored.  The users are attentive and helpful within limits.  The equipment is twelve volt and sealed.

Dish networks equipment is commercially available and moderately portable.  Most hospitals probably already subscribe. Adding an up-link for those occasions when the phone system fails seems a modest added cost.

The few seconds delay in emergency communication looks not to matter much at times of phone failure.


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