Smartphone design is the work of turning bought-in parts into a finished phone that works well. The phone brand buys the main chip from a chip company and usually uses Android as its operating system. It then designs the handset around them, and writes the software that makes all the parts work together. ODM stands for original design manufacturer: a company that designs and builds phones that another brand sells under its own name. Many brands design some models themselves and have others designed by an ODM.
Three kinds of company can be involved. The brand decides what the phone should be, and sells it. An ODM may do the design and building for the brand. A contract manufacturer, called an EMS company (electronics manufacturing services), assembles the phones in its factories. Most phones sold in India are assembled in India, in factories in Noida, Chennai and Bengaluru. A government scheme called the Production Linked Incentive (PLI) pays makers an incentive on the extra phones they make in India.
Imagine a phone brand planning a ₹18,000 5G phone for India. The work usually takes 12 to 18 months.
First, it chooses the main chip, the system-on-chip (SoC). For the chip company, being chosen is a design win. The chip company also supplies a reference design: a sample circuit board and base software that show how to use the chip.
Second, its engineers lay out the circuit board and fit everything into a case about 8 mm thick. The hardest part is the radio. They place the antennas and tune the RF front end for every 4G and 5G band used by Indian operators.
Third, they choose the screen and its touch and display chips, the cameras, the battery and the memory.
Fourth, the software team adapts Android to this exact hardware. It writes the drivers, the programs that let the operating system use each part. It sets up the firmware that controls charging, the cameras and the sensors. It tunes the camera software over hundreds of test photos, adds dual-SIM support and checks every Indian language the phone will offer.
Fifth, the phone is tested. Engineers drop it, heat it to 45°C, and test calls and data on each operator's network. In India, phones must also be certified under the Bureau of Indian Standards (BIS) before they can be sold.
Finally, the phones are assembled in a factory in Noida and sent to shops and online sellers.
Brands that once designed only phones now also design new kinds of device, such as AI hardware devices that answer spoken questions. One phone brand, now part of a large PC maker, designs its phones partly in Bengaluru. Phone design is also one of the few places where chip companies, software engineers and factory engineers all work on the same product. The layers of firmware, apps and servers that a phone connects are explained on IoT architecture.