MODEL RELEASED. Woman using a mobile telephone, thermogram. The thermogram shows the emission of infrared radiation, displaying it as colour-coded surface temperatures. The range shown is from 23 degrees Celsius (purple), through blue, green and red, up to 35 degrees Celsius (yellow). The woman's face is warm compared to the phone and her hair and clothing. A mobile phone is a portable device that is used to send and receive voice, text and picture data as low-intensity microwaves.