NEW ORLEANS—Tuesday afternoon’s keynote session at CTIA Wireless 2012 was a curtain call for four of the participants from last year’s roster, but the Jim Cramer-led discussion certainly had a different atmosphere.

At last year’s show, the CNBC financial journalist sat with three carrier chief executives a short time after the announcement that AT&T was going to pay $39 billion to acquire T-Mobile USA. The explosive news, which continues to have an echo in the industry, electrified the crowd that morning in Orlando, Fla.

Returning to the stage Tuesday afternoon were Cramer, Verizon Wireless CEO and President Dan Mead, AT&T Mobility CEO and President Ralph de la Vega, and Sprint Nextel CEO Dan Hesse. T-Mobile CEO Philipp Humm, who had been scheduled to appear last year but bowed out at the last minute, also was on Tuesday’s panel.

Mead led off the session with a summary of the network and service innovations the U.S. wireless industry has experienced in the last decade. But the Verizon chief warned that the lack of new spectrum is a danger for the future.

“We need additional spectrum to reach the marketplace soon,” he said, adding that Verizon can’t wait long before the spectrum crunch is felt. “We need to get unused spectrum in the hands of those who can make innovations.”

Hesse also noted the impact wireless telecom has had in the U.S. but said it is sad that the industry has the worst reputation of any industry among consumers.

“Wireless service is part of the social fabric of nearly everyone in the country,” Hesse said. “Wireless devices are critical to the way we conduct our lives.”

Hesse said personalization and trust are critical for the future of the industry. He said Sprint and other carriers are trying to build trust with their customers by working with partners on security and privacy.

Humm referred to last year’s AT&T Mobility merger and breakup by saying T-Mobile’s brand suffered because of the failed acquisition. Humm said T-Mobile is intent on relaunching its brand and making 4G service affordable.

Humm got in a dig at AT&T at the end of his speech by showing a new T-Mobile TV ad that showed the operator’s T-Mobile Girl on a motorcycle speeding past an AT&T rider. De la Vega, who appeared after him, rebounded with a magazine study of nine markets which showed AT&T Mobility had the fastest network.

De la Vega said the real challenge for networks is to be innovative. AT&T has a corporate crowd-sourcing program that asks employees to provide innovative ideas. The carrier has 120,000 employees participating in the program and has developed more than 50 innovations they have suggested, he said.

One example he gave is AT&T’s new digital solutions, which starts with home security and later home automation. The service, called Digital Life, was unveiled at the show.

“We believe it will change the way people live, work and play,” De la Vega said of AT&T Digital Life.