VOIP and PSTN - can I just have one phone?

[#1]

Hi,
I've a BT (soon to be plus) analogue phone line.
I have plus broadband.
Is there anyway I can connect my existing PSTN phone so it can make and receive PSTN calls, and can make and receive VOIP calls, without having to connect via a PC?
It maybe I need a new phone or box to control whether its routed via PSTN or VOIP (VOIP at peak, PSTN at all other times), but prefereably I would want that to be controlled by whatever I would need to plug into my router.
Is this what I want?
http://www.sipgate.co.uk/voipshop/c460ip
Thanks in advance,
Steve

[#2]

Yes you are correct , you need a box called a VOIP Adapter ( or ATA ). The Siemens one you quote will certainly work and also includes a Dect Phone IIRC. I'm pretty sure that someone has got that one working with Plusnet, check some of the other posts.
There are lots of ATA's out there have a look at http://www.broadbandbuyer.co.uk/default_ShopGroup.asp?ShopGroupID=96
that provides a useful explanation.
To be able to use it for PSTN and VOIP you need one with FXS and FXO ports. If you are willing to use your existing phone you can pick up ATA's from £20 upwards on Ebay.

[#3]

Brilliant, thanks very much for the info.
I shall look around at the reviews/prices, and will need one which allows lowest cost routing rules to be set up.
Not sure about which voip provider to go with yet though - will take a look around.
Thanks,
Steve

[#4]

Hi Steve
I have the siemens 460ip dect phone its brillant.  Very very easy to setup base stations about £80 and extra handsets are about £39 each.
You can make a pstn call on 1 handset and get an other voip phone number on an other.
Come and have a look on the beta voip trial to find out more or pm me anytime for help
Regards
Puddy
ps dont forget you can choose any std code in the uk and free 240 mins of free voip calls with plusnet (depending on tarriff)