A few adds to what Mike said about level 4 (<20C, <-5F) and colder:
Consider taking a winter survival course if you are going to be winter dry camping. Have multiple contingencies to stay warm. A good 7-9" loft, -40F down bag is a good thing to have when your other heat sources fail. Propane vaporization rates drop rapidly at level 4 temperatures and colder
Cell phones can be used in an emergency, when coverage exists. Triangulation by cell tower, in limited coverage areas, results in very large search areas. GPS coordinates are better. Cell phone apps are available which show your actual GPS coordinates, or sends these to 911 as either a voice call or text message.
Large parts of MT, BC and AB have no cell phone coverage, or where you are may have a pocket of no coverage. A PLB (personal locator beacon, 5-6 oz, and 10-12 cubic inches) will directly send your GPS location to search and rescue personnel via satellite, as well as provide an analog signal to radio direction locate you once they get to the GPS location.
McMurdo - FastFind or
ACR Artex - ResQLink are two that I have.