A thought: Do you have "anonymous call rejection" enabled on your voice options page?
I haven't used that feature so I don't know whether there's a record in the call details info when that is the reason a call is rejected. It's also unclear why an alarm company would not be providing caller id. I can confirm that NMR blocked calls do show up as "blocked" rather than "external" in the "Type" column of the voice usage details page.
I haven't used that feature so I don't know whether there's a record in the call details info when that is the reason a call is rejected. It's also unclear why an alarm company would not be providing caller id. I can confirm that NMR blocked calls do show up as "blocked" rather than "external" in the "Type" column of the voice usage details page.