I started off as a Phlink user (similar to PhoneValet) and was really disappointed when Phlink stopped being supported years ago. I ended up going with PhoneValet and have happily used it for a couple of years now.
A few months ago PhoneValet announced they were discontinuing the product. Fortunately, they would continue supporting it for a few more months (support ends in June 2012).
So, I started thinking about alternatives. I used Phlink/PhoneValet for its phone tree and time of day announcements. I looked at GoogleVoice (not enough features) and some others that wouldn't fit the bill. Then I started looking into auto-attendant subscription solutions. They sound like they would work great, but they charge you for every minute you use your phone, not just the time you are using the auto-attendant.
I wanted a system I could just purchase and have it be my own. After racking my brain I figured out a great solution... buy an old MacMini and run and old OS on it! No monitor needed.
I could get one from ebay for $100 - $120, but decided to make a call out on Facebook to my friends. I had a friend who was willing to just give it to me as it was just sitting in a closet.
I installed and mounted it in my closet and hooked it up to the network. I used my iMac as a monitor so I could set up file sharing on it and just use screen sharing for the future. Super easy to just screen share with it if you need to access it.
It works great with PhoneValet (just got done this morning with it). Just keep an older OS on it.
To me this was the best solution for me. Maybe one day a better answer system will come along. But, I am up and running and thrilled.
Hope this helps someone. I know I racked my brain over this for months.
NOTE: After I got my MacMini, I found this great website for them that mentioned how to make them run as a PBX using something called Asterisk (opensource). I don't know anything about it, but it might help someone:
http://www.macminiserver.com/can-a-mac- ... -as-a-pbx/