T-Mobile's new US TV ad for its myTouch 4G smartphone makes its point by mocking the popular iPhone, through a parody of Apple's own long-running "I'm a Mac" advertising campaign.

In the T-Mobile ad, a svelte young woman, outfitted in T-Mobile's characteristic magenta colour, introduces herself as a myTouch 4G. The camera draws back showing a young man on her right, who introduces himself as an iPhone 4, dressed in black, but it's a strained introduction because he's carrying piggyback an older, larger man whom he identifies as the AT&T network. "That'll slow you down," says the woman.

She announces that the myTouch, on T-Mobile's HSPA+ plus network, can offer video chatting almost anywhere (anywhere the network is available), without having to use Wi-Fi. The AT&T network character reminds the others that iPhone 4 can run its Facetime video chats anywhere a Wi-Fi network is available, "like in an airport."

"Suddenly, you feel heavier," says the iPhone 4 character.

T-Mobile now claims its expanding HSPA+ network is the nation's "largest 4G network." The carrier itself remains the smallest of the four main U.S. mobile carriers.

The T-Mobile ad is the latest in a slew of new smartphone ads straining for potential customers' attention. Microsoft is ramping up its campaign for the new Windows Phone 7 phones by stressing a message of how simple devices running its mobile OS will be vs. other smartphones.

Back-and-forth ads between AT&T and Verizon over the past year were particularly aggressive.