How can I have a special notification for a text message from someone not in my contacts?

[AC Question]

I have a Samsung S7 and am looking to have a special notification for when i get a message from a number not in my contact list. For background, I am a volunteer fire fighter and the dispatch system uses a text message to inform us when a call comes in. The problem is that every text message shows as being sent from a new number so, I can't directly flag the number. Right now I'm using a workaround by changing by default notification sound to the new louder alert, and individually changing the notification sounds for each of my contacts.

 

[Dooki]

That is about all you can do.

However, do they use a rotation of numbers? As in, they use 50 different numbers but they all get used again? If so, you might be able to save them all to one contact. It might take awhile to get them all on there but I don't think there is a limit to how many numbers you can save under one contact.