[Hawk]

My point is that the slider is plastic, and shouldn't interfere with the signal at all. If you try other cases and do not have this problem, then it is clearly the case, but if other cases are doing it too, then I suggest going to Apple and have them inspect the phone. Incase is an approved accessories vendor, and if their cases are now inadvertently blocking cell signal, then it needs to be brought to the attention of both Incase and Apple.