The U.S. government doesn’t seem very troubled, either. The Food and Drug Administration says on its website that research generally doesn’t link cell phones to any health problem. And although the Federal Communications Commission requires manufacturers to include information in user manuals about cell-phone handling, that’s often buried deep in the fine print.

Our recommendation is to reduce your exposure from wireless sources. We advocate what’s referred to as the Precautionary Principle. Basically, this means that because there’s research, lots of it actually, saying the energy that powers our cellphones (RF radiation) could be causing health concerns like tumors and cancer. We ought to take care when using our cell phones and all devices that emit RF, using them mindfully.
A full featured desktop or wall mount corded telephone (no microwaves) combined with a special ultra low EMF headset. You get all the benefits of a normal telephone without putting yourself close to the strong magnetic fields associated with the handset, speakerphone, or phone base. The special headset cord is about 3 feet long and uses a plastic tube to carry the sound to your ear. Absolutely no electronics, wires or magnets are near your ear. Cord provides distance from telephone base and traditional handset, convenient mobility, and can be extended up to 15 feet with option extension cord, sold separately (see below). Tested and approved by Less EMF Inc., dramatic field reduction when the headset is used. Although pictured as white, our current stock is a black phone.
We couldn't find one legit EMF expert online or anywhere else that would recommend a radiation blocking case or anti-radiation case. Not the Environmental Health Trust or Magda Havas, or Joel Moskowitz, in fact his site, safeEMR cautions against scams and claims for radiation protection.  So if a so-called "EMF expert" is recommending any kind of anti-radiation case, they probably aren't that much of an expert. 

The frequency of radiofrequency electromagnetic radiation ranges from 30 kilohertz (30 kHz, or 30,000 Hz) to 300 gigahertz (300 GHz, or 300 billion Hz). Electromagnetic fields in the radiofrequency range are used for telecommunications applications, including cell phones, televisions, and radio transmissions. The human body absorbs energy from devices that emit radiofrequency electromagnetic radiation. The dose of the absorbed energy is estimated using a measure called the specific absorption rate (SAR), which is expressed in watts per kilogram of body weight.