226-721-5700 called and CallerID said "Unknown Caller". Dead silence when I answered the call. I held down the * key for 15 seconds and they were disconnected. I've been called by the Canadian Diabetes Clothesline people before and they were legit. I wonder if this call was from a robo-caller that was falsely ID'ing as them and was checking lines to see if they're in service. I think most calls that say nothing at all are bots doing that.