Ok I have found a lot more info now, and know what they are sending me. It seams there is 2 devices available, the one they are sending is a D-Link VA
The D-link is for connection to a router only, while a V-Portal is basically the same as the D-link but also has a 1 port router built in.
They did ask if I had a router, had I said no, I would have been sent the V-Portal, which might have been better. I can buy them from Vonage for £9.99
I always switch everything off at night, including the modem, its done automatically when I switch off the PC (Inteli Plugs) so was thinking it might be better to leave the modem on, and have a phone line on...
However thinking about it, if I go to bed then my answering machine is on anyway, and I will never answer the phone zzzzzzzzzz...
So now if I still switch off everything, the Vonage system has a feature to take a message if it cannot ring me, and the message is emailed to me as well as it being available to listen to online, so no real problem.
Even the mobile phone diverts to voicemail when its off