BT500 works quite well when paired with Linux. To get the thing working you will need BlueZ stack (already in recent kernels), utilities (bluez-utils.spec) and ALSA Bluetooth driver – snd-bt-sco. There is one issue with BT500 (where you will hear no sound, just single beep at start and end of audio stream) which is handled by sco-mtu patch.

After setting headset in paring mode issue:

[root@tarm ~]# hcitool inq
Inquiring …
00:07:A4:BE:95:EE clock offset: 0x51ed class: 0x200404

Then pair with bt500:

[root@tarm ~]# hcitool cc 00:07:A4:BE:95:EE
[root@tarm ~]#

you will be asked for PIN code (enter: 0000).

[root@tarm ~]# btsco -v 00:07:A4:BE:95:EE
btsco v0.41
Device is 1:0
Voice setting: 0x0060
RFCOMM channel 1 connected
recieved AT*GNMK

From now one there should be second ALSA card available:

[root@tarm ~]# cat /proc/asound/cards
0 [Intel ]: HDA-Intel – HDA Intel
HDA Intel at 0xb0000000 irq 169
1 [Headset ]: Bluetooth SCO – BT Headset
BT Headset 1

Run your favorite application (twinkle perhaps – very nice SIP phone with G.711 support, ideal for connecting to Asterisk PBX) and choose BT Headset in sound setup (available also trough OSS emulation as /dev/dsp1 in my case).

You can view setting using alsamixer or amixer using -c 1 switch:

[root@tarm ~]# amixer -c 1
Simple mixer control ‘Master’,0
Capabilities: volume volume-joined
Playback channels: Mono
Capture channels: Mono
Limits: 0 – 15
Mono: 0 [0%]
Simple mixer control ‘Mic’,0
Capabilities: volume volume-joined
Playback channels: Mono
Capture channels: Mono
Limits: 0 – 15
Mono: 0 [0%]
Simple mixer control ‘AGC’,0
Capabilities: pswitch pswitch-joined
Playback channels: Mono
Mono: Playback [off]
Simple mixer control ‘Loopback’,0
Capabilities: pswitch pswitch-joined
Playback channels: Mono
Mono: Playback [off]

When pressing buttons on headset the commands are sent to Bluetooth dongle and are visible by btsco program. You can put your own script in .btscorc which will be executed when commands arrive. By this method you can for example connect hang up button on headset with skype disconnect button (through skype DBUS API).