It appears that, for what ever reason, the City of Waco has installed a force field that blocks phone usage. That's right folks, NO calls go IN, and NO calls go OUT. Land line and cellular. Not quite sure how they have managed this, but it's true.
When people get with in a 50 mile radius of the wonderful city their phones to not work. You can't even text. Email function is disabled also. It's very sad.
Energy shields usually work by absorbing or dissipating energy. prolonged exposure to such energy weakens the shield and eventually results in the shield's collapse, making the phone systems work again on a limited basis until the shield is repaired. Calls that are able to seep through do so during the time with the shield is at it's weakest.
In addition the shields function in an unexplained manner and serve as a primary protection against weapons fire from enemy vehicles; these shields also generally block the use of transporters while active. Also, inside vehicles, force field generators can seal off vehicle atmosphere from the vacuum of space, as in the case of a hull breach caused by an attack or explosion.
So you see, while there is a down side to the shield (no phone usage) there is an upside as well (your ship, oops I mean VEHICLE is safe from interstellar attack!)
Come on, you KNOW you are LAUGHING your BUTT OFF!