I am using a Plantronic Voyager PRO or Nokia HS-36W headset.
Parring is ok as well as call pick-up and release.
But after some use it drops calls at pick-up.
It also goes from BT headset (blinking headset lamp) to headsset jack (steady lamp) at pick-up.
Only a power recycle of the SPA525G will recover for BT headset use.
To me it clearly seems to be a FW bug.