161T-Ratings: Phones rated T3 or T4 meet FCC requirements and are likely to be moreusable with a hearing device’s telecoil (“T Switch” or “Telephone Switch”) thanunrated phones. T4 is the better/higher of the two ratings. (Note that not all hearingdevices have telecoils in them.)Hearing devices may also be measured for immunity to this type of interference.Your hearing device manufacturer or hearing health professional may help you findresults for your hearing device. The more immune your hearing aid is, the less likelyyou are to experience interference noise from mobile phones.Other Medical DevicesIf you use any other personal medical devices, consult the manufacturer of yourdevice to determine if it is adequately shielded from external RF energy. Yourphysician may be able to assist you in obtaining this information. Switch your phoneoff in health care facilities when any regulations posted in these areas instruct you todo so. Hospitals or health care facilities may be using equipment that could besensitive to external RF energy.VehiclesRF signals may affect improperly installed or inadequately shielded electronicsystems in motor vehicles. Check with the manufacturer or its representativeregarding your vehicle. You should also consult the manufacturer of any equipmentthat has been added to your vehicle.Posted FacilitiesSwitch your phone off in any facility where posted notices require you to do so.Potentially Explosive EnvironmentsSwitch your phone off when in any area with a potentially explosive atmosphere andobey all signs and instructions. Sparks in such areas could cause an explosion or fireresulting in bodily injury or even death.Users are advised to switch the phone off while at a refueling point (service station).Users are reminded of the need to observe restrictions on the use of radio equipmentin fuel depots (fuel storage and distribution areas), chemical plants or where blastingoperations are in progress.Areas with a potentially explosive atmosphere are often but not always clearlymarked. They include below deck on boats, chemical transfer or storage facilities,vehicles using liquefied petroleum gas (such as propane or butane), areas where theair contains chemicals or particles, such as grain, dust or metal powders, and anyother area where you would normally be advised to turn off your vehicle engine.