It is possible to restrict some basic cell phones to calling 911 or numbers that have been set up in advance as speed dial numbers. When my daughter got her first phone we set it up that way and I know that some phones are still that way.

IMO that's why the firefly never caught on. It was possible to do the same thing with a normal phone on the plan you already have.
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"There is not a man of us who does not at times need a helping hand to be stretched out to him, and then shame upon him who will not stretch out the helping hand to his brother." -Theodore Roosevelt