Masayoshi Son, who is also CEO of a Japanese carrier, says the network quality in the US "is not something you should be proud of," and directly calls out his rivals.
The carrier continues its torrid pace of subscriber growth amid stiff competition in the wireless business.
The microblogger's executives say they have no idea when they could see "significant" additions to its monthly active users metric.
AT&T tops expectations for its second-quarter earnings, and manages to grow its base despite losing core phone customers.
But the nation's largest wireless did post a profit for the second quarter and phone subscriber growth that topped expectations.
The company's announcement follows a report from research firm TrendForce revealing that Huawei is now China's top smartphone brand.
Also coming soon: Skylake, the code name for Intel's sixth-generation Core processor aimed at PCs, is slated to drop during the second half of 2015.
After two quarters as the leader of the pack, Apple has dropped to third place in the world's largest smartphone market, says research firm Canalys.
From autonomous warfare to still-distant sentience, artificial intelligence in 2015 is nothing like we expected. Here are three things every geek who dreamed of a robot future needs to know.
In 2014, the Swedish music-streaming service's revenue reportedly rose 45 percent to $1.1 billion, but attempts to build out products nearly doubled its operating loss.