"Ask the other caller to hang up" ...?
It has been my experience, that doesn't even work.
If I'm on the phone, and someone else calls me, I click over, talk to them, conclude that call, and then click back to my original call, only to see that other caller is still "on hold" forever. There is no way to make the phone realize that other caller has disconnected. All I can do is click "Hang up on all", which disconnects the other phantom call, and also disconnects my currently active call, which is just stupid.
There's really no way around this?!
I swear I didn't have this problem with my Treo 800w, or Centro, both also on Sprint.