Bad reception can be caused by many things. The most common problem is the distance to the closest tower. Cell waves, like any frequency wave, degrade with distance. They are weaker the further they are from the tower.Interference with cell signal can also cause interference. This can happen because of certain building structures such as steel walls or concrete exteriors. The signal could be affected by other frequencies, like cell phone, radio and TV signals.Last but not least, signal strength can become a problem if there are many people in the same location using the same mobile service. The bandwidth has been split to allow for multiple users.