I got a Vonage VoIP setup, and it has proved to be a pain in the arse, mostly NOT to do with Vonage.
The local phone company obviously doesn't want to lose out, so what have they done? If someone in my area code dials either: XXX-YYYY or XXX-YYY-ZZZZ it is meant to come through (7 digits still work here which is nice).
However, ONLY 1-XXX-YYY-ZZZZ seems to actually work from a local land line in the same area code. The company will NOT route another number through. This is just another PITA things that they are doing to drag their heals. I have also heard that although you are meant to be able to transfer your numbers around, they sometimes make it REALLY hard. :(