Check with your wireline service provider to see if they offer voice activation services on their end so you don't need to upgrade the wireline phone. You would then dial one number out (add it to speed dial) and then say who you want to call.

Sometimes voice activation is more trouble then its worth. My parents have bad vision so I bought this "
Big-Button Phone" from radio shack (Model: 43-172, Catalog #: 43-172). They can see the numbers and also see the red light flash when calls are coming in.