Jennifer Aniston, Jon Hamm sign on for "Stand Up to Cancer"

Jennifer Aniston, Jon Hamm, Halle Berry, Reese Witherspoon and Kiefer Sutherland want to connect with you about cancer.

They are among the stars slated to appear on "Stand Up to Cancer," the hour-long telethon set to air Sept. 5 on 31 broadcast and cable networks simultaneously.

Other celebrity participants announced Wednesday include Pierce Brosnan, Rob Lowe, Will Ferrell, Ben Stiller, Eric Stonestreet and Kareem Abdul-Jabbar.

Rather than the stars staffing phone banks as they have on past "Stand Up to Cancer" telethons, they'll be contacting with viewers by phone and online through Facebook and other platforms from a "digital lounge" hosted by Katie Couric. Fans can sign up for the "We're Calling You" initiative beginning Wednesday at werecallingyou.org.

"We'll have plenty of stars reaching out to donors via social media, thanking them through Facebook messages, digital shout outs, Instagrams and tweets," Couric said. "In other words, this year, we are so 2014!"

"Instead of people calling in with the hope of talking to a celebrity, stars will be calling and sending social shout-outs to viewers at home," Couric said.

The "Stand Up to Cancer" special will also feature performances by Jennifer Hudson, Ariana Grande, The Who, Common & Lupe Fiasco and Dave Matthews.

For the first time, the telethon will include a Canadian co-broadcast, with funds raised benefiting research and awareness programs in Canada.

Funds raised by the telethon support international, inter-disciplinary scientific research aimed at discovering new treatments for various types of cancer. Since its first broadcast in 2008, Stand Up to Cancer has pledged more than $260 million.