New to VoIP,
There is a product on the market that is exactly what you are looking for. It is the QTelNet IP-1301 phone. It is a 2 in 1 phone VoIP and PSTN. If you are using VoIP through a 3rd party company versus setting up your own network you will have to do a little configuration. I use it on my desk in my office .. it is nice to only have one phone for both. I did a search on Google and it looks like it is $579.00 USD at http://telephonymarketing.com/~telephon/cgi-bin/cart.cgi/000133.html?id=q39q9GPq