They can still call 911 by holding down the 9 key:
Authorities tracked down a 4-year-old girl who called 911 nearly 300 times last month by offering to deliver McDonald's to her suburban Chicago apartment.
Unbeknownst to her mother, the girl used a deactivated cell phone to call dispatchers 287 times in June—sometimes as often as 20 times a shift.
Dispatchers heard the child's voice but could only track the phone's signal to the apartment complex.
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Under federal law, deactivated cell phones still must be able to access 911. Many deactivated phones will contact an emergency call center if the user holds down the nine key.