Yes, that would probably be a good thing. They seriously need to fix the problem of being able to listen to other people's voicemail by merely setting the caller id to the target's cell number and calling them.
Wait is that a thing right now?!
You bet it is, I think the first time I tried this was around 2007 or something like that.
Is that why I need to enter a passcode? I always thought that was stupid.
If you call from another number you get prompted for the passcode. If you call from your "own" number no passcode is needed.
I'm not certain that's the case. At least since I've had a phone (~8 years), I've always had to enter a VM password.