A beeping from dash when turning ignition off

[oro]

I have noticed 4 beeps from the dash area when turning off the engine, [[size=14]b]this does not happen everytine[/b[/size]]. I have not been able to associate the beeps with any particular action as yet.
Any thoughts on what this might be?

[Gaffers]

Depends on whether you have any hands free device and what car stereo you have.

[Danny]

sony stereo head unit?

[oro]

there is a Nokia handsfree kit fitted (I have never used it, don't know how it works) - the sterio is the Phillips + Bose

[TheBoy]

Failing power sounder batteries, and its coming from scuttle area, passenger side

[sluggi]

Faulty power sounder! Batterys proberly dead

[sluggi]

Beaten by tb just

[oro]

Power Sounder batteries, ok, where do I get them from, are they easy to replace, what do they do?
many thanks for diagnosis.
Mike