Do not be surprised or offended if I fail to answer my phone.
Partly, I'm just a jerk who sometimes ignores calls, but mostly I actually do miss them, especially on weeknights. During the week I'm often not home until 10:00 or later. I can't say "usually," but it's often enough that if you call me during that window of time and I don't pick up, it probably means my ringer is off. I do listen to my voicemail, and your call will probably be returned the next day.
It's not personal, and I'm not avoiding you.