I currently have my TX115 set up so that, when it rings, the call is answered as soon as I open the clamshell. This makes me wonder if it's possible to decline a call without opening the clamshell. Would one of the volume keys do it, perhaps? The manual doesn't seem to be much use.
If I can't figure out a way to do it, then I guess I'll have to set it so that I have to press [send] or [end] when the phone is ringing.