I seem to remember a case, possibly in Sweden in the late 90's or early 00's, where a woman was unable to call an ambulance for her husband who was having a heart attack, because of an incoming caller who had not hung up properly (or something along those lines). After some panic I think she ran to a neighbours house where she was able to make the call.

If I remember the story correctly, this resulted in some debate followed by a law change, such that now if the called party hangs up, you have only a few seconds before the connection is broken.

I don't know how it went for the husband though...