Prevent iPhone from dialing 911 I have a family member who has dementia. Their iPhone was taken away because they kept dialing 911. I gave the family member an iPod Touch, but they really want an iPhone. I took the SIM card out of the iPhone, but discovered that it is still possible to call 911. 

Is there a way to disable the 911 dialing functionality of the iPhone in the United States?
No, you cannot disable it for an US iPhone as US law requires that all cell phones be able to call 911 even if no SIM-card is inserted.

You would need to obtain a foreign iPhone. For example in the EU the emergency services are typically not dialed with 911 but rather 112.