The .e4 blog has a good new post on power-over-ethernet, which I see as an often overlooked area of SOHO VoIP. It goes into some detail P.O.E. network switches, power management and mid-span P.O.E injectors.
While some of our larger offices have P.O.E. capable network switches I use a couple of simple single-port mid-span power injectors from Aastra. Why? They’re simply a better, and more cost effective solution for my small office. I only need to power a couple of devices over the ethernet, just my Polycom desk phones. However, I need gigabit ethernet bandwidth in a number of places. POE capable gigabit switches were on the expensive side when last I reworked the office network. In contrast, single port power injectors can be had for around $40 each.