Hmm, I haven't actually tried this, but since the board is 12VDC, you could probably power your demo with a single 12V lantern battery (or two 6v lantern batts in series). That'd get you lamps, buzzers, intercom.. might even handle powering the 12V ring generator (a PowerDsine) as well for bells and everything. A portable PBX, lol.
Or maybe you can re-purpose some of those 12V rechargeable lithium batts many screw guns use, which probably have more amp hours, and is easy to recharge. I actually have a 12V screw gun with a pair of batts.. I guess I should try a test to see how long I can run a couple of phones this way.. will follow up if I can.
