The problem with this device is it only works between two phones with the same hardware attached.. now if you are, for example, having a heart attack, this is of no use at all trying to reach 9-1-1 for Medics to come save our life.
And I for one can only assisst if 1: you let me know you need help and 2: For a short period of time so if help does not arrive, you are .. Late.
On the other hand. Very little of this country is not covered by Ham Radio, A technician license gives you coverage from 10 meters up.. a General or Extra does even better.. This morning I was sitting here in S.E. Ga listening to stations all over eastern USA... (interesting thing,, It was 75 Degrees here, Same as in Upper Michigan just off the lake) I could hear the Michigan station clearly and had say HE suddenly said he needed EMS.. I'd have been on it fast (As it happens my database has the local EMS/Police number in it) (I used to be a Police dispatcher in MI) Likewise he could have made the call for ME. I might add I am only pushing 100 watts into the wire.
I have both made and relayed Emergency calls over the years...