Re:Benefit for the average home? (Score 5, Informative)

The benifits as I see them:

Multiline. Several people can be calling at once. (Provided the voip provider doesn't mind. Unlimited plans usually forbid this, but per minute plans have no such restrictions.)

Multi-mailbox. You can assign a different mailbox to different members of the household.

Multi-number. You can have multiple phone numbers in different geographic areas. You can even get cheap 800 numbers that cost 2cents/min. All these can be funneled to the same phones.

Telemarketer avoidence. You can have a top-level voice menu that asks people to press 1 for person-a, 2 for person-b etc. If they don't press anything the call is dropped. The predictice dialers that telemarketers use won't press anything, so the call never rings any of your phones.

Per-callerid call-routing. Calls from people you'd rather not talk to can go direct to voice mail or get blocked. (jokingly refered to as the ex-girlfriend option in the asterisk documentation.)

Better voice quality on the voicemail. Most home answering machines compress the crap out of the incoming and outgoing messages. Computer disks are cheap enough and voice only takes 64kbits/sec uncompressed anyway, so you can just keep it in the native telco-format and not lose any voice quality on the messages.

call accounting. If you do consulting, you often want to keep track of how long you spent on the phone with each customer. Asterisk automatically logs every incoming and outgoing call with the exact call start and end times.