Hi Juan,
He is a link to Plantronics website with a list of headsets they support with the SPA525G's.
http://www.plantronics.com/us/configurator/default.jsp?use=Deskphone&wl=&ec=&sl=&spn=&skb=&sds=
The Voyager Legend looks like that may be a good option. Plantronics supports this headset with Bluetooth and as long as you the right phone load with Bluetooth enabled, then you should not have any issues.
Hope this helps.
Regards,
Chris
