I can say that the Verizon Airfone's required a credit card to use for anything other than calling our operations control center at Delta (*OCC) or our medical advisors (*PMD)...so if calls were made to relatives of the passengers on board, there would have to be a credit card record of the call. I do not believe you can call 911 from those phones, at least at Delta. We have since have them removed from our aircraft due to complaints about technical difficulties (seemed like they were never working).
I have never seen a cell phone work in flight, although I have seen countless passengers try to find a signal in flight, to no avail. I even tried one myself when I was desperate to get a hold of my mother during an in-flight emergency I wasn't sure I was going to survive. No luck.
This was one of the things that seemed very suspicious to me...cell phones just don't work in flight, no matter the altitude...the speed at which we travel makes it too difficult for the phones to find a tower to route the call through.
http://pilotsfor911truth.org/forum//index.php?s=&showtopic=12&view=findpost&p=10695795