Plantronics HD Pro and iPhone 4, ios7

I have had recent problem with my earpiece. I can pair, re-pair, or force phone to route audio through earpiece. I cannot force the Plantronics to assume

control of the phone for dialing when I turn the earpiece on, only when I get or make a call, then select the voyager instead of the iPhone. Then it'll work until I put the earpiece down or turn off.

Where is the command to force the iPhone to relinquish control to the Plantronics when it is present and on, in position.

I thought this was supposed to be an automatic fxn of the Plantronics and why it was as expensive as it is.