I've been using a OBi200 to use Google Voice for my home phone service. It works great (even for 911) and I've saved a bundle of money! Unfortunately Google will discontinue XMPP support on May 15, so I had to switch to another VOIP provider. Still at $40/year for service, its much cheaper than if I would have gone with my telecom.
Honestly, telephony can make computers look simple. Programming dial plans is different than any language I have learned. I guess the standard was developed long before there was a basic or COBOL. Strange.
The line signaling is another challenge. And interfacing with POTS (plain old telephone signaling) vs SIP gets pretty hairy.
Asterisk does an excellent job of making it all possible, but it can be a challenge. There are some pre packaged asterisk boxes or DVD with a GUI you might try. Or if you are a massochist like me you can build it from source.
On the other hand I have carried one of my SIP phones with me to China. Plug it into the hotel room Ethernet and dial a "1" to call the extension in my kitchen back home. Unbelievable sound quality. Then the phone rang, it was my niece asking if I was at home.... Uh, no!
It took me a good week to get my first box programmed. But once you learn all the quirks it settles down.
#Aquaponics , explains Matthew, uses fish waste to produce nutrients for plants, and plants to clean up the water for the fish; he's built a system controlled and monitored by a Raspberry Pi and currently populated by goldfish, a sort of tightly managed pseudo-pond. Or, as his friend Geoff calls it, a sudo pond.