From 2003, small firms in mainland China made cheap mobile phones known as shanzhai ji. Chinese Wikipedia says the name came from their low cost, their good value and their failure to follow the rules of the industry. Before October 15, 2007, when the State Council announced the end of the approval system for phone production, such phones rarely had brands of their own.
One common type was made by a small firm that rented a production license from a licensed maker.
According to the same article, a MediaTek chip of 2006 combined the main board and the software and lowered the barrier to making a phone. Shenzhen’s Huaqiangbei became the largest wholesale market for these phones. Typical features were very loud speakers, two SIM cards in one phone, and phones for the elderly with large characters and large keys.