The first phone that harnesses Google Inc.’s ambition to make the Internet easy to use on the go was unveiled yesterday, and it looks a lot like an iPhone.

T-Mobile USA showed off the G1, a phone that, like Apple Inc.’s iPhone, has a large touch screen. But it also packs a trackball, a slide-out keyboard, and easy access to Google’s e-mail and mapping programs.

T-Mobile said it will begin selling the G1 for $179 with a two-year contract. The device hits American stores October 22 and heads to Britain in November and other European countries early next year.

The phone will be sold in T-Mobile stores only in the American cities where the company has rolled out its faster, third-generation wireless data network. By launch, that will be 21 cities, including New York, Los Angeles, Houston, and Miami.

In other areas, people will be able to buy the phone from T-Mobile’s Web site. The phone does work on T-Mobile’s slower data network, but it’s optimized for the faster networks. It can also connect at Wi-Fi hotspots.

The data plan for the phone will cost $25 per month on top of the calling service, at the low end of the range for data plans at American wireless carriers. And at $179, the G1 is $20 less than the least expensive iPhone in America.

Android, the free software powering the G1, is a crucial building block in Google’s efforts to make its search engine and other services as accessible on cell phones as they already are on personal computers. The company believes it eventually might make more money selling advertisements that get shown on mobile devices than on PCs, a channel that will generate about $20 billion in revenue this year.

Both Yahoo Inc. and Microsoft Corp. also are investing heavily in the mobile market in hopes of preventing Google from extending the dominance it enjoys in searches initiated on PCs.