Some mobile phones have only one line beside them, while others have two or even three lines.
These wires may be high-frequency coaxial wires used to connect the two motherboards of the mobile phone to transmit power or data, or they may be antennas.
Most mobile phones are generally designed in three stages. The upper part is a large motherboard with a large number of components, the middle part is usually a battery, and the lower part is a small auxiliary board with a microphone welded to the microusb interface of the mobile phone. If there is only one line inside such a mobile phone, it is undoubtedly a high-frequency coaxial line, and the antenna may be designed on the plastic inner shell that protects the motherboard.