Mobile phones (also known as cellular or cellphones) allow communication from any location via a network of base stations. The information is transmitted from the mobile phone to the base station and vice versa via high-frequency electromagnetic fields.
Radiation intensity is greatest close to its source, i.e. a mobile phone’s antenna. The radiation is only strong while the phone is transmitting, not while it is in idle state. The radiation decreases sharply with distance to the phone.