Noise due to distance is a confusing case that shouldn't really be called noise, but is because it can be reduced by Noise Reduction; it doesn't really exist until an action is picked-- Meaning, Noise due to distance can't stop you from using your commlink at all, but if you decide to send a command to something really far away, your device may be unable to actually perform that action because the Noise would shut off the wireless. I'm not really convinced that's working as intended though. Otherwise, if a R4 Commlink is in a Spam Area creating 4 Noise, and someone turns on a R6 Jammer, the commlink is now facing 10 Noise and its 2 NR simply brings the Noise down to 8, not enough to make a difference in terms of "can I use my commlink yet".
To suppress an alarm, you'd need to think about what the alarm actually is and where it's coming from. If the alarm relies on an outside device telling it to work (like, it only functions when there's a device telling it to sound, and defaults to Off otherwise) then you could use Control Device or Spoof Command to tell that device to stop. Or alternative to send an "all clear" message if that's the case. If you're inside the host and this device isn't slaved to the host, then you'll have to leave the host first. There's reasons for a site to have all their guards' commlinks slaved to the host, and there's reasons to not do that, so it isn't a given which it'll be.
Devices slaved to a host ignore noise in relation to things inside the host. What that means is, you can never receive a penalty from noise on any action you're taking inside a host-- Even if it's targeting a physical device, as long as that device is slaved to the host. It adds to hosts basically being their own little matrix worlds.