It sounds like your phone is not receiving signal at all times. I think the messages you receive following missed calls comes from Fido's voicemail notification service. I'm not sure why the American Flag shows, though. I, too, received one of those messages to notify me that there was a voicemail left. I think it might have been when Fido switched to a new voicemail system, perhaps?? I usually get voicemail-to-text notifications, but that day I received both the American Flag one as well as the text transcript. I now only receive the transcript version which appears to come from the caller's phone number.