well a website would work if everyone had the internet, or knew how to use it. i would be surprised if most potential sellers that call me knew how to use the internet.
i use RingCentral. it's $119/year. I get a 800 number as well as different extensions. they also do a good job at call forwarding and you can set up your rules accordingly. if you don't want to get calls to your cell phone at night, while your at home, you can set up the answer rule to send it to your house phone depending on the time of day.
it's also nice because your phone will ring and it will say, "you have an incoming call, to accept, press one" so you pick it up by pressing one or you just listen to the message to see who it easy, you can interrupt at any time.
this is good for me because i use my house line as my biz line. sometimes i'm too busy to take down the info of a seller, so it let's me know it is someone calling the 800 number and to let it go to VM.
there is nothign better than actually answering the phone.