FERPA honestly affects something as simple as contacting a student via phone if it's not a personal mobile number, because you could have a spouse unaware of the fact that their significant other is taking classes. Perhaps, there are valid reasons for that individual to want to keep their education private. So you can't just spout off information about the institution and reason for your call if leaving a message. Your working relationship with the student is essentially private information and should be treated as such -- whether that's calling at risk students about progress or refusing to discuss grades/ progress with a family member -- unless express permission was given.