My current way of doing this seems to work part of the time but it is still the best I've found/come up with so far.
I used autohotkey to create a shortcut (ctrl shift alt b in my case) that disables the bluetooth handsfree // support service. I also created one to open up the sound settings window (ctrl shift alt d) so I can force connect/disconnect as needed. Here is the code (you must create an admin-access shortcut to the .bat as a .lnk file)
.bat:
net stop DeviceAssociationService
net stop bthserv
net stop BthHFSrv
autohotkey (also disconnects top two audio devices in your list):
^!+b:: EnvGet, DROPBOX, DROPBOX ;not necessary - I just share
autohotkey scripts across computers and have dropbox stored in
different places hence the environment variable
Run %DROPBOX%\Code\Services\utils\batcommands\bstop.lnk ;replace with
your .lnk address
Run, mmsys.cpl WinWait,Sound
SetControlDelay -1
ControlClick,X96 Y110,Sound,,R
ControlSend,SysListView321,{Down 3}{ENTER}
ControlClick,X96 Y160,Sound,,R ControlSend,SysListView321,{Down
3}{ENTER}
ControlClick,OK return
^!+d:: Run, mmsys.cpl
return
This issue exists for any paired bluetooth device under windows. There is no option to turn auto connect off, like JNK says in the comment under his answer. Super annoying but true. Even if you manually disconnect the phone, but leave them paired, if your windows goes into lockscreen or sleep or anything, it will autoconnect AGAIN after returning from lockscreen/sleep... – Leo – 2017-07-02T10:55:03.193
As you'll have noticed, without the particular make and model of phone all you'll get is generic answers. Please provide the make and model (and ideally firmware revision if you know it). – Cry Havok – 2010-10-20T06:26:29.183
You need bluetooth headset that support HSP http://www.bluetooth.com/English/Technology/Works/pages/hsp.aspx
– None – 2010-10-20T03:14:54.137