Phone call segregation

Hello,

I would only like my cell phone to ring when someone dials my desk phone # or extension directly and not when the main line # is dialed.  It seems like I would accomplish this by turning off the call ques that I am in while leaving the mobile app setting on, but I would have to keep going back to toggle that on and off. I want the main line to function as it does, but segregate the cell phone call when someone calls me directly.....