This is a regression from bug 717434 and it makes us not hear the dial tone.
Created attachment 593689 [details] [diff] [review]
So, the regression was that an outgoing call was not marked the active call, and so we weren't turning audio on. The fix I'm proposing here also changes the value of navigator.mozTelephony.active in these situations, but IMHO to the right value.
Landed ages ago, forgot to mark RESOLVED/FIXED.