According to General relativity the clocks in our satellites in the atmosphere tick faster than those on Earth, as they are farther from the gravitational well of Earth and are free falling.
According to Newtonian mechanics and Gauss theorem, a hollow massive spherical shell has no net gravitational field at any point inside the shell as the geometry cancels out the pull from each extrema.
I would imagine that this does not change in GR (am I wrong?), an object inside should be free falling. But does time behave different inside the shell and outside very far from the shell?