Alteratively to the above, and perhaps depending upon how you receive calls, you can also go to inbound rules and establish a a DID using the number of interest. Then you can follow this link for the rest of the setup.
http://www.3cx.com/forums/display-the-name-associated-with-a-did-when-ringing-queue-28821.html
There will be a few minor variations based upon your need/desire, but the key is that using the caller-id info allows for certain routings to occur and in your case, you can input the number of interest, select the type of mask or number upon which to react, and then direct accordingly.