Oh… What a mistake I made.
I changed the email address on my Apple account. I spent the past two days finding out that it didn't update my log-ins so my messaging, FaceTime, iCloud (calendar, password, and contact updates), all ceased to work or notify me of calls, messages, and backups… seamless became senseless.
It's fixed now, however, it cost me a day of frustration and some missed connections. Words of warning, "Don't change it unless you really need to!"