EL SEGUNDO, Calif. — Volunteers for Joe Biden's phone banks have been getting some unexpected pep talks from Hollywood's A-listers.

Starting with Bradley Whitford (The West Wing) and more recently with Kristen Bell, celebrities have been "Zoom-bombing" the occasional phone bank across the U.S. in support of the presidential hopeful as part of a new series by the campaign.

As seen in Bell's viral video with Good Place co-star Ted Danson, the actors take time to speak with volunteers and show their appreciation. And the volunteers are just thrilled by the surprise.

“The reason that they love it is because they’re getting thanked for their great work and volunteerism, and they deserve to be thanked for it," said former Biden speechwriter Mathew Littman, who co-produces each Zoom bomb. "These people are working really hard. So it’s super pleasant, very positive, feel-good, and then it gets released on the Joe Biden YouTube page.”

It takes a great deal of coordination to deliver each Zoom bomb, Littman explained.

"You not only have to get a group of volunteers together — you’ve got to get the campaign production team together, our producers together. Our editors have to have the occasion to do it," he said.

There will be another Zoom bomb released this Sunday, and Littman reports they have others in the works as Election Day nears.

The celebrities involved in future appearances remain a secret, of course. "We have one coming up [with] volunteers in Ohio, I can tell you that," said Littman.

Hollywood remains active in Biden's campaign with its own entertainment phone bank, which Littman helps organize once a week. Talent such as Alyssa Milano and Madam Secretary showrunner David Grae have been involved in weeks past.