Japan's No. 1 carrier, NTT DoCoMo (NYSE: DCM), just reported a monthly subscriber loss of nearly 67,000. This comes during the month when NTT DoCoMo finally became an official Apple (AAPL 1.27%) iPhone carrier, which should have helped it stem its ongoing customer losses to smaller rivals KDDI and SoftBank. NTT DoCoMo attributed the problem to inventory issues, since it was unable to fully meet demand.

That storyline is peculiar, since the same iPhone model is compatible with all Japanese networks, which suggests that perhaps Apple didn't allocate supply adequately. Ultimately, Apple suffers only if there is unmet demand, since it has less interest in which specific carrier is chosen. 

Hopefully, Apple doesn't do likewise when it inevitably adds China Mobile (CHL) as an official carrier partner, which could happen as soon as next month. Technical hurdles have historically held back a partnership with China Mobile and Apple, but that is no longer a concern.

In this segment of Tech Teardown, Erin Kennedy discusses NTT DoCoMo's woes with Jamal Carnette and Evan Niu, CFA.