This thread may be long dead but for those who might be trying the same thing, some notes from the AudioManager docs may be useful. It looks like the missing element is the startBluetoothSco() command but there are restrictions on the use of this channel. From the Android Dev site here:
public void startBluetoothSco () Since: API Level 8 Start bluetooth SCO
audio connection.Requires Permission:
MODIFY_AUDIO_SETTINGS.This method can be used by
applications wanting to send and
received audio to/from a bluetooth SCO
headset while the phone is not in
call.As the SCO connection establishment
can take several seconds, applications
should not rely on the connection to
be available when the method returns
but instead register to receive the
intent ACTION_SCO_AUDIO_STATE_CHANGED
and wait for the state to be
SCO_AUDIO_STATE_CONNECTED.As the connection is not guaranteed to
succeed, applications must wait for
this intent with a timeout.When finished with the SCO connection
or if the establishment times out, the
application must call
stopBluetoothSco() to clear the
request and turn down the bluetooth
connection.Even if a SCO connection is
established, the following
restrictions apply on audio output
streams so that they can be routed to
SCO headset: – the stream type must be
STREAM_VOICE_CALL – the format must be
mono – the sampling must be 16kHz or
8kHzThe following restrictions apply on
input streams: – the format must be
mono – the sampling must be 8kHzNote that the phone application always
has the priority on the usage of the
SCO connection for telephony. If this
method is called while the phone is in
call it will be ignored. Similarly, if
a call is received or sent while an
application is using the SCO
connection, the connection will be
lost for the application and NOT
returned automatically when the call
ends.See Also stopBluetoothSco()
ACTION_SCO_AUDIO_STATE_CHANGED
Note that I have not tested this, I’m just passing along a lead I found in researching a similar project. I think Jayesh was close to the solution and the restrictions above may have been what was keeping it from working.