BlueAnt X3 Micro and T630

I just picked up a BlueAnt X3 Micro to use with my SonyEricsson T630. It
pairs fine and works ok, people can hear me and I can hear them.

It's a bit crackly though. With the X3 in my right ear and the phone in
my left pocket, reception becomes patchy. If I take the phone out of my
pocket and wave it around in front of my hand everything's fine again.
If I'm in the quiet environment of my house I can sit the phone on my
desk and use the headset a couple of meters away, but nowhere near the
stated 10m range of Bluetooth.

Does the T630 implementation of Bluetooth suck, does the X3 have a poor
Bluetooth antenna/transmitter, have I got a dud unit or is this just the
way it works?

Cheers, Robert.