LOS ANGELES — In television’s latest quest to discourage viewers from skipping ads, actors from NBC and ABC shows are appearing in character in commercials to interact with products in parallel story lines.

This new kind of commercial further blurs the line between program and advertisement and comes as traditional product placements within shows, an early response to fast-forwarding, have become common.

A series of spots that debuted this week weaves Palm Inc.’s Pre phone more deeply into the story line of two prime-time dramas.

In a “mini-mystery” called “Another Desperate Housewife,” an extra from ABC’s “Desperate Housewives” suspects her husband is cheating after checking his Pre. A voice-over refers to Sprint’s wireless data network, as the phone is offered exclusively through Sprint Nextel Corp. in the U.S.: “This is suspicion, on The Now Network.”

Along its eight-week run, a few dramatic twists and turns will be revealed — over the phone, of course.

Sprint also has a “Heroes” series of dramatized ads on NBC that follows new character Lydia, who is able to identify faces in the shape-shifting tattoos on her body. She uses the Pre to find her daughter, who also has a heroic power.

“It looks and feels and has all the drama and excitement of the show,” said Denise Ocasio, managing partner of MindShare, the marketing firm that helped Sprint create the spots. “It is an entertainment experience. It’s just brought to you by Sprint.”

But not everyone is pleased. Peter Horton, executive producer of the short-lived NBC drama “The Philanthropist,” said a dramatized vignette featuring the assistant and bodyguard of the show’s main character using Microsoft Corp.’s Bing search engine was confusing to viewers because it sometimes introduced a competing plot line.

“I do think it’s at the expense of the viewing experience, I really do,” Horton said.

Microsoft was happier with the results. Danielle Tiedt, a marketing general manager at Microsoft, said the ads did “a great job” of boosting understanding and awareness of Bing.

Networks want to convince advertisers that coupling such creative shorts with a fleet of traditional ads improves the ads’ effectiveness at a time marketing budgets are being slashed.

Such innovation is critical as more consumers fast-forward through ads, easily accomplished with digital video recorders.

Another development two years ago also gave broadcasters the push to keep audiences tuned in during commercials: Instead of basing ad rates on a TV show’s audience ratings, they were set on the number of people watching commercials.

“As a result, cable and broadcast companies are much more interested in making sure they maintain as much of the audience in the commercial break as much as possible,” said David Poltrack, chief research officer at CBS Corp. “That is creating a lot of integrated advertising.”