If compliance with 5.9.1 is your goal in this, then we do have a spare output on the board which can be used for an alarm output. A suitable resistor and driver is all that would be required. The output would be limited to a critical alarm only though to marry up with other customers requirements. For integration into a tactile alarm you would be well advised to speak directly to Kevin.
You could integrate such an annunciator into the handset as there is room, but that design would still fall under Kevins intellectual property and it is only right he should benifit.

Brent


p.s.
Appologies to Kevin. Post edited.