It is paying heavily for that obstinacy - with a net 3.2 million users jumping ship to its two domestic rivals over the last 4-1/2 years - but is determined to protect the walled garden of services it has built around its own smartphones.
"We're trying to develop a lifestyle system," NTT DoCoMo CEO Kaoru Kato told Reuters in an interview this week.
DoCoMo is insisting on allowing its own services and apps preloaded on to the device -- something Apple does not allow. Customers and even some higher up executives are urging DoCoMo to cave in and sign an iPhone/Apple deal but the carrier is not showing any signs of backing down.
DoCoMo has in fact created many services for its customers to use, but those services such as photo sharing have been surpassed in popularity by other third party applications such as Instagram or Twitter.
"Unit sales are doing quite well this year but they're still losing customers to other networks," said Hiroshi Yamashina, senior telecoms analyst at BNP Paribas. "If that's the case then they really have no choice but to go for the iPhone."
For now, Google is hoping to retain customers with smartphones running Android with marketing efforts this summer focused on Samsung and Sony devices.
It does not seem like any iPhone deal is near -- but if Samsung's S4 were to pick up ground it could be Apple needing an iPhone DoCoMo deal.