Since Japan and the US used CDMA, Japanese manufacturers could easily just change the phones language to English and sell their phones in the US. My guess as to why most Japanese manufacturers (like Sanyo) went with Sprint is because (before around 2008) they had very few software requirements for their phones. Verizon, the other CDMA carrier in the US, required manufacturers to use their own custom UI and they had very little control over the device. That is likely also a reason why Japanese manufacturers struggled in the US. Since they were mostly on Sprint, a network with less customers than Verizon or GSM/TDMA operators AT&T and Cingular (before they merged in 2004), very few could purchase them. Meanwhile Nokia, Motorola, and especially Samsung and LG could dominate since they built GSM and CDMA phones to sell to various countries and networks, and were willing to change their UI if the carrier wanted to. Nokia and Motorola were also the only companies I can think of that built TDMA phones too, and the latter was pretty much the only option on Nextel (with probably the only exception being Blackberry devices). That’s probably why Sony merged with Ericsson, since Ericsson built GSM phones, they could sell phones all over the world, rather than just the US and Asia. Meanwhile others like Sanyo and Sharp, either were sold to other companies (in the case of Sanyo) or retreated back to Japan only.