The Proximity API for Spokes and Voyager Pro UC v2 headset is available in the current release of Spokes 2.6 SDK.
Note: You need the currently available firmware upgrades for Voyager Pro headset and BT300 dongle from Plantronics.com my headset updater. http://www.plantronics.com/uk/support/myheadset/updater/
Some notes from Ramesh about using it here:
http://developer.plantronics.com/community/proximity-beta/blog/2012/01/27/spokes-headset-proximity
Pat’s draft specification here:
http://developer.plantronics.com/docs/DOC-1132
Known issue 18442 (with workaround):
http://developer.plantronics.com/docs/DOC-1130
Sample apps using proximity on PDC site:
Presence, Proximity and Caller ID Sample.zip:
http://developer.plantronics.com/docs/DOC-1083
How To Get Your Voyager Pro UC to Tweet
http://developer.plantronics.com/blogs/Cary/2012/05/06/how-to-get-your-headset-a-tweeting