Connecting external phonenumbers to LYNC

Hello,

I have no idea yet how or what is the right question.

I have installed Lync on my system in Hyper-V which is working. So customers can call us from external (pstn) and we get in on our Lync.
But I would like to have eg 4 PSTNnumbers.
And per department there are 3 (of thos 4 numbers) for different departments and so they should ring on the LYNCusers of that certain department.
eg numbers :
+3211124590 is the general number that should ring at the reception desk.
+3211124591 should ring at the station/user of the secreatry of department A
+3211124592 should ring at the station/user of the secreatry of department B plus her assistent.
+3211124593 should ring at the station/user of the secreatry of department C plus two of her assistents.

Are these just SIP-numbers I have to order and then create 4 dialplans or ??