Define the phone requirements
Design the hardware architecture
Select the processor and modem
Choose memory and storage components
Select the display panel
Choose the battery and power management system
Design the main circuit board
Select cameras, speakers, microphones, and sensors
Design the antenna system
Develop the operating system software
Develop the firmware and drivers
Design the user interface
Prototype the device
Test electrical performance
Test wireless connectivity
Test battery life
Test thermal performance
Test durability and reliability
Refine the design
Prepare manufacturing tooling
Source components
Assemble the device
Install software and calibrate components
Perform quality control checks
Package the phone
Distribute the product