By law even disconnected cell phones can make 911 calls, and cell phones are supposed to let the caller know when a 911 call is in progress, but this type of alert could be dangerous.
Carol (last name withheld) from Austin, Texas, called for help recently when she arrived at some vacant property she owns and found her security chain gone. To her horror, her new Casio G’zOne phone from Verizon Wireless, made an audible alarm when she called 911. It wasn't ear-piercing, but considering how quiet it was, it would have been quite audible several yards away.
Apparently the vandals were already gone, so she was OK. Still, why such a loud audible alarm, that could let criminals where a victim is hiding?
According to Verizon Wireless, the audible tone is required by the Federal Communications Commission. It's another "accessibility" feature that Congress mandated. This is in regards to Section 255 of the Telecommunications Act which requires telecommunications products and services to be accessible to people with disabilities.
Since, as I stated above, the cell phone has to alert the user they have dialed 911, this is the solution for blind people. The loud alert is designed to let blind people know they've dialed 911. But by making it loud, they've created a problem.
It's been confirmed on forums on cell phone-centric websites that this occurs on other cell phones as well, so it looks like the issue is going to become more prevalent. Although Section 255 states there has to be a cue, like most of these regulations, I don't believe it specifies exactly how that cue is given (readers, correct me if I'm wrong).
So before people start blaming the government, perhaps it's the manufacturers and their interpretation that needs fixing. The solution (IMHO): vibrate on an outgoing 911 call. This not only helps blind people, but deaf people as well.