The mute out put will be trapped and earthed- hence speech comes up. Standard Renault sign when mute is activated.

Remove the stereo and check the outputs on the bottom of the iso block connectors.

The top will have all 8 wires in- this is speakers.

Bottom will have/need. Earth, Live, Switch live.
It will also have Illumination and possibly a remote aerial or 2nd live.

My guess is at some point it will have had a handsfree kit fitted to it and there is remenants of it still attached to the back of the stereo.
Look for a yellow wire maybe if its Nokia..

I dont have any pics to hand I am afraid.

Jake