[plug] [OTish] IP Phones general info?

[Steve Baker]

Hi,

I have several offices around the place (Freo, West Perth, Vancouver, 
soon adding Kalgoorlie, SAfrica, SAmerica) that are connected via IPSec 
net-to-net VPN tunnels using Linux (on topic.. for a second...)

I was thinking about the wonders of VOIP, about which I know little to 
nothing.  I was wondering if I could just plug in IP phones in each 
office, assign an IP address to the phone, tell it to call a phone at a 
particular IP address elswhere on the WAN and it would Just Work ?

Do IP phones in fact actually work this way?

If this is the case, can I get some software on the desktop workstations 
(Windows) and have them talk to the phones, and vice-versa?  I know 
about Skype and such, but those type of protocols don't NAT too well and 
I'd rather have all the traffic go through the IPSec tunnel.

Thanks.

Steve