The problem
Carrier voicemail is a walled garden: dial in, listen linearly, press 7 to delete, and hope you remember what was said. It cannot be searched, forwarded, or read in a meeting. And on a shared house line, everyone’s messages are in one pile.
What this does
Separate mailboxes — kids, adults, family — each with its own greeting and
its own message-waiting lamp. A ladder that goes unanswered lands in the mailbox
that belongs to whoever it was for.
Messages are delivered to email, with the audio attached. That means they are searchable, forwardable, and readable on a train.
Why per-mailbox matters more than it sounds
The lamp is the useful part. A handset with a lit MWI is telling one specific person that something is waiting for them. On a shared mailbox the lamp means “somebody has a message”, which is the same as no information at all.
mailbox = "adults" on a handset decides which lamp it follows, so a phone in a
shared room can still point at a specific box.
Details worth knowing
Dial *97 from any handset to reach the mailbox that handset is pointed at
— no PIN dance to get to your own messages from your own phone.
Change the PINs. The shipped examples use an obvious placeholder, and
scripts/smoke.sh fails if they are still in place, because a comment saying
“change this” is not a check.
The mailbox is the fallback for everything. House ring, ladder, quiet hours — all of them end in a mailbox if one is configured, and in a polite dismissal if not. Which of those you want is a real choice, not a default.