I know the headset is a first-party brand accessory made specifically for the Xbox 360. I don't own this headset so I can't really test it myself, but from the looks of it, I think it's only made to connect the console, nothing else.

Try to see if you can connect it to your PC (through bluetooth) and use as a headset. If it works on PC, then it'll probably work on your smartphone too. Just follow the main procedure.

Video tutorial: http://www.youtube.com/watch?v=vr3_q2fB1II

[EDIT] I was looking at the old headset. As for the new one, I think it could be possible. Just be sure to put it in discovery mode when you're switching between different devices. When it comes to single button bluetooth headsets, it's difficult to unpair once it's already paired to a device. So take note of that and be careful.

// Roth