AT&T is swapping cute kids for helpful nerds in its latest TV campaign, debuting Sunday night when seeds are decided for the March Madness NCAA college basketball tournament.

The new work marks the end of the carrier's popular, precocious-kid-starring "It's Not Complicated" series, which has been running since November 2012.

The new campaign will play on an old slogan, "Nothing But Network." Rather than focusing on claims about the breadth or strength of coverage, "Better Network" will highlight the nuts-and-bolts of the wireless infrastructure, said Chad Harris, executive director-marketing at AT&T Mobility.

"We're finding that consumers are curious to know why the network does or doesn't work," he said.

The campaign will get heavy rotation during the Final Four, set to take place in Dallas, AT&T's backyard. AT&T is toning down its war with T-Mobile with fresh print and digital ads introducing its "Building You a Better Network" campaign.

In the ads, two nerdy AT&T engineers, tweak the network cells inside an office and antenna inside a stadium, detailing the process endearingly to onlookers.

The campaign arrives after a contentious week for the major U.S. carriers. Masayoshi Son, chairman of Sprint, visited the U.S. to lobby for a potential merger with T-Mobile. He spent considerable time thrashing the wireless networks of the carriers, including his own, and pledged a "price war" with AT&T and Verizon Wireless if allowed to acquire T-Mobile.

For over a year after a failed merger attempt, T-Mobile and AT&T have been at each other's throats with ads. The wireless operators use the GSM technology, meaning they can steal customers from each other more easily than Verizon or Sprint.

While AT&T is toning it down a bit, T-Mobile spokeswoman Paula Gottlob said her company's ads, including those directed at AT&T, "will continue to run their planned media course."

AT&T is going heavy in the Dallas area in and around the stadium that carries its name. When the Final Four begins in April, AT&T will blast fans with ads plastered across the city from the time they leave the airport to the minute they arrive at AT&T Stadium.

AT&T is also sponsoring the NCAA March Madness Live app, designed for fans live-streaming the games. It's also sponsoring an app for TV host Conan O'Brien that allows users to hand-pick the camera angles during the show's live broadcast, if they want to tune in on their phones.

For the "Better Network" campaign, AT&T is sticking with BBDO, the agency behind the "It's Not Complicated" spots.