That very much depends on the locale for the latter. If I call 911 and either hang up after they answer or if you say that it is not an emergency but rather a mistake or test, they'll still arrive where I am.
Can they get your location if you call 911 and hang up from a cellphone?
Where I live (in Canada), one time I did some test using a VOIP application, I have no idea why or how, but it caused a call to 911 (I didn't even saw the call...). They called some minutes later to see if everything was alright and when I said it was probably my test using VOIP that caused that, they understood instantly, like it wasn't unusual.
I started Dash911 and more recently MultiAlert911. In every case we've test called a PSAP, as long as we clearly started the call with "this is a non emergency VOIP test call" we had no problems.
