Twenty-five years ago this week, following a speech by then-Federal Communications Commission Chairman Charles Ferris, C-SPAN host and founder Brian Lamb opened up the station’s phone lines to take live viewer calls. The first call, which came from Yankton, S.D., marked the beginning of what would become television’s first-ever regularly scheduled national viewer call-in program.

A quarter-century later, network officials estimate that more than a half-million viewer phone calls and some 46,000 call-in segments have aired on C-SPAN channels.

Capitol Hill’s hometown television network will celebrate the 25th anniversary of its first viewer call-in this weekend with a 25-hour call-in marathon beginning at 8 p.m. Friday.

Each hour of the marathon will take a look at key events from each of C-SPAN’s 25 years, starting with 1980, and will include interviews with guests who helped shape or cover the highlighted event.

“The idea of a 25-hour call-in program may seem a little crazy, but call-ins are the essence of C-SPAN,” Lamb said in a release. “We couldn’t think of a better way to celebrate a format that’s given a voice to the public and helped shape the political debate.”

The marathon’s first guest Friday evening will be Phil Donahue, who is credited with pioneering the call-in format on television when he launched his show on WLWD-TV in Ohio in 1967. And throughout the wee hours of the night and all the next day a rotating panel of C-SPAN hosts will keep the phone lines open as they interview Washington, D.C., policymakers, including former Speaker Tom Foley (D-Wash.), and prominent Washington journalists, such as Susan Page and Sally Quinn.

Twenty-five winners of an essay contest sponsored by C-SPAN also will participate in the marathon. The winners — young and old, self-proclaimed C-SPAN junkies and more casual viewers — each submitted essays describing why they watch or participate in call-in programs on C-SPAN.

On Saturday evening, the contest’s grand- prize winner Erika Barger, a high school senior from Ormand Beach, Fla., will join Lamb and scheduled guests William Kristol of The Weekly Standard and Frank Rich of The New York Times for a discussion on the war in Iraq.

In her winning essay, Barger, who said she watches C-SPAN’s Washington Journal before heading to school, said her most memorable call-in moment came one morning when Sam Wineburg, a professor at Stanford University, was a guest.

“He stated that students rarely read history books for pleasure and most cannot properly date the Civil War,” she wrote. “As a history buff, I knew I had to call in and let all know that this does not apply to all students. … Sam Wineburg seemed quite surprised that a high school sophomore would be calling C-SPAN on a Friday morning to respond to his comments.

“Since that time, it has given me greater confidence to listen to others’ opinions,” she wrote. “What they have to say is important to them. They desire to be heard, and deserve that chance.”