Mindia and the rest of you IP telephony users :p, it is a great technology but be cautious of 911 and emergency calls.
Also make sure you have an alternate route for voice traffic, like a cell phone, keep an analog line, etc. No power, no phone, that sort of sucks. Analog old as sin but has no AC power requirements.
Not sure about the details but I've read several snips where vonage and some other ip telephony services were in some sort of litigations lawsuit deal becuase 911 calls got dropped, or couldn't be routed at all.
Also note that IP telephony phone conversations are recorded, not stored (yet) but recorded. It is a requirement for IP telephony. Every "bit" you speak is written on a hard drive someplace, then near instantly regurgiated to voice. I can post more details if you like :p. No I'm not the ultra paranoid that thinks every current analog converstaion is recorded and analyzed by the NSA.
IMHO IP telephony will become a bane soon enough. Looking forward I'd go so far to say that IP telephony will become a standard or commonplace, as will permenant record of every phone call
(win for thw lawyers tho :p )
EDIT:
Wanted to add a bit on 911. In the US, a 911 call from any analog line can nearly pinpoint your location very quickly. IP Telephony, not so, the call of origin is never your location but some HUB city sometimes in a different state alltogether.