Cisco Headset Adapter for iPhone Headset
It's works as advertised. It does exactly what you expect it to. I'm using it with Etymotics Hf2 earbuds and a Cisco 7941 phone. I did confirm that the button on your iphone line mic does not do anything, but I don't think that's a limitation of this adapter. It seems none of the cisco headsets have any kind of button on them, so I guess the cisco headset port doesn't support anything.