A couple of minor things:
There are other Obi devices like the 110 and the 1xxx series but including them might complicate the simple explanation.
The Obi202 has a router built in and also supports Wifi in case you don't have a hardwired connection nearby.
Although Google is a great way to get free service, often times a Voip account with a different provider can be easier to set up. Many problem here in the forums are Google-based.
Still, a great video.
