Hardware: The newly released Snom One Mini ($599) is a small-office/home-office IP-PBX server that draws just 60 kWh of power per year. If you want a completely in-house VoIP setup, you'll need to buy a PSTN gateway to connect VoIP calls to the public telephone network; such devices cost about $250 and up, and require an active landline. The Snom One Mini, however, was designed around the idea of using an external VoIP provider that provides "SIP trunking" services to handle the analog-to-digital signal conversion. Using one of those services would allow you to skip the PSTN gateway.
Finally, you'll need SIP phones. As with the other services discussed here, the phones that Snom sells directly--priced at $70 to $100 each--work best with this system due to their plug-and-play support. Other SIP phones or analog phones with adapters will also work, but they'll require manual configuration with Snom's server software.
Price: Hardware pricing aside, the cost of this kind of VoIP service will vary according to the provider you choose. Skype Connect, for example, costs $7 per channel per month, plus 0.8 cent per minute on outgoing calls. The number of channels you purchase determines how many simultaneous calls the service will support. 8x8 is another popular business-oriented VoIP service provider, but you'll need to request a quote from the company to get pricing information.
Features: The Snom One Mini supports Power over Ethernet, so you don't need an AC outlet to set it up. It supports SIP-enabled devices, and it has no moving parts. In addition, you can configure the Linux-based IP-PBX to include VPN, DHCP, VLAN, and other services.
As for software, the Snom One Mini IP-PBX includes: