I was having approx 4-5 drop calls a day without a bumper. Since placing the bumper approx 4 days ago no drop calls with a stong signal. My wife returned her iphone 4 prior to buying a bumper (she just prefers the feel of 3gs better), but was having atleast 10 drop calls a day. Would have loved to see if the bumper would have corrected her phone issue. Many cases out there I guess but the bumper does work very well. Also have invinsable shield to help protect front/back.