This day has been a long time coming, but at long last Apple (NASDAQ:AAPL) is launching the iPhone on China Mobile's (NYSE:CHL) network on Friday. Ahead of the launch, CEO Tim Cook sat down with The Wall Street Journal to discuss the potential of the partnership. Naturally, he's quite optimistic about getting the iPhone on the largest carrier in the world.

Apple will expand its iPhone distribution by 3,000 points of sale. He also teased that Apple sold more iPhone units into its Greater China segment than ever before. That's certainly impressive, but investors won't have a concrete frame of reference, since Apple doesn't disclose the geographical mix of iPhone sale. Investors won't have to wait long for Apple to report last quarter's overall results, though, which are due out on Jan. 27.

In this segment of Tech Teardown, Erin Kennedy discusses Apple's big launch with Evan Niu, CFA, our tech and telecom bureau chief.