The airport I fly to/from is a satellite airport in an outlying class C. On the sectional the airport is just outside the airspace. When i takeoff from it and transition through the C, i will usually call up approach when im around 200-300 ft below the C. For example in the shelf where this airport is the floor of the C starts at 2300' however ill call up approach around 2000' make 2 way they give a beacon code and will usually identify me or have me ident. So the thing i am wondering is if they can see me on the screen below the C or do i have to be at the 2300' feet before they can say "n123 radar contact..." ?