Notification of extension use

I am trying to track usage of certain public phones (inbound/outbound) by extension. I need run a routine immediately when the outbound call is made or an inbound call is answered.

I have the outbound portion working by using macro-dialout-trunk-predial-hook. Can anyone give me a clue how to do this for inbound on only specific extensions. I foresee it being inserted perhaps where the Follow-Me announcement would be in the dialplan.

Thank you.