While Nokia remains slightly unpopular in North America, the Finnish phonemaker remains a dominant brand according to the latest figures from International Data Corporation (IDC). The report says the the top three smartphone manufacturers in the world are Nokia, Samsung, and Apple, in that order.

LG drops to fourth place with a 4.1-percent share, leading China-based company ZTE by a mere 0.1%. The Korean electronics company suffered a staggering 42.2-percent loss in the last twelve months. Analysts from IDC say the drop is caused partly by the worldwide rejection of feature phones in favor of smartphones.
The decline of demand for feature phones are mostly felt in its major markets like China, India, and Indonesia.
The consumer behavior toward smartphones, meanwhile, vary by region. Apple’s iPhone 4S was well-received in North America, Australia, Hong Kong, Korea, and Taiwan, while mid-range Android phones (from Chinese companies such as Lenovo, Coolpad, and Huawei) are popular in Mainland China.
Samsung’s Android handsets dominate Central Europe, Middle East, Africa, and the rest of the Asia-Pacific region. Consumers in North America also demand for 4G LTE smartphones as well as BlackBerry phones running on BB OS 7, while their counterparts in Latin America begin to favor the sub-$200 Android models although low-cost features phones continue to rule the market.
source: idc
Obviously, Nokia is the most popular phone maker company and it's has create one image in the customer mind and for that customer have trust on every product of the Nokia because it can provide the cheap service to their customer and increase the customer satisfaction. That's why it is leading smart phone company.