We are tourists from abroad. Brought an old iphone 4 with us to put prepaid sim card into. We purchased a prepaid sim from a Koodo store in Calgary (Market Malls), and activated the service. To test it, we phoned a friend in Calgary and it worked. Next day we went to Banff and had no service. A week later we returned to Calgary, and still the phone says no service. Have tried switching the phone off and on, and re-inserting the sim. It says "searching..." and then says: "No service". This is near Calgary airport. We logged into our prepaid account and everything seems fine there.