Apple and Samsung Electronics ended struggling Nokia's 15-year reign at the top of the smartphone sales rankings in the second quarter, researchers said on Friday.

Nokia has dominated the smartphone market ever since its 1996 launch of the Communicator model, but competition from its two nearest rivals and a slump in its own sales sent it straight from first to third place in the three months to June as growth in the sector starts to slow.

Apple sold a record 20.3 million iPhones in the quarter despite the fact that its iPhone 4 model is now more than a year old. Usually success of smartphone models does not last so long.

Apple unveiled its sales last week, but on Friday analysts also estimated Samsung sold 19 million smartphones in the quarter, well ahead of Nokia's 16.7 million as it was able to benefit from booming demand with smartphones using Google's Android software.

Samsung's Galaxy portfolio has proven popular, especially the high-tier S2 Android model, said Neil Mawston, analyst at Strategy Analytics.

Strategy Analytics estimated smartphone market volume grew 76 percent from a year ago in the second quarter. ABI Research was somewhat more cautious estimating market grew 62 percent.