There is an issue where if you load a 3rd party building and you hold the alarm button, it will go off as normal (using the custom sound), where as if you were to release it, instead of playing the custom alarm release sound effect it uses the original alarm ending sound effect (which is normally bell1-stop.wav unless it has been manually configured). The best example of this happening would be in BENO's Coalham Hospital where the main elevators (or lifts, if you are not in the US) would activate the phone once the alarm button is released. This happens in both 1.11 alpha and in alpha 10 (1.10). I know for sure that BENO edition skyscrapersim, as well as Alphas 7 & 8 will not have this issue. If someone will fix this, then great!
I don't know how to fix, this topic may been dead...
Try asking someone for Help.