Rdio has never looked like more of an underdog than it does now. The beautifully made but underused streaming music app has never had more competition than it does today, and that competition has never been stronger. Spotify's investment in social and discovery features has blunted Rdio's traditional advantage in product, and the company now has more than 20 million subscribers. More than 11 million people have signed up for the three-month Apple Music trial. Rdio doesn't share its subscriber numbers, but it's safe to say its user base is a small fraction of those.

Two years ago, terrestrial radio company Cumulus invested in Rdio with an eye toward bridging online and offline music. The idea was that Cumulus would promote Rdio on its 500-plus radio stations, and Rdio would help Cumulus develop a digital strategy. So far, Cumulus seemingly hasn't done much besides sell advertising on Rdio's free, ad-supported stations. But tomorrow the companies are getting hitched in a more meaningful way: you'll be able to listen to Cumulus' radio stations inside the Rdio app for Android and iOS. (The announcement was scheduled to go out Wednesday, but Rdio leaked it in their Android release notes.) Music, talk, and sports radio will all be found within the app.

For many fans of streaming music apps, terrestrial radio stations sound like a step backward — they're choked with ads, work from tiny playlists, and lack meaningful ways to interact with them. Rdio can't do much about the first two issues, but it has made the stations interactive: it displays metadata for the song you're listening to in real time, and will show you the most recent 20 songs played on the station. From there, you can download the track to your phone, add it to a playlist, or share it with a friend. If you grew up with a local radio station and playing it reminds you of home, having it in Rdio might be a bonus. Over time, the company plans to add radio stations owned by other companies.

Rdio needs to grow faster

For Rdio, the good news is that Cumulus stations have promised to promote the app on the air with significant frequency. DJs will tell listeners to download the app so they can keep in touch with K-BEEF 107.7 ("The Beef") even when they're not commuting to work. Given how many people still listen to terrestrial radio, it could be a meaningful way to help Rdio build an audience. People love radio apps: the iHeartRadio app, developed by the company formerly known as Clear Channel, has been downloaded tens of millions of times. Clear Channel even renamed itself after the thing, though that was likely driven just as much by its toxic corporate reputation. "There's a big audience we think we can speak to in a meaningful way," says Chris Becherer, head of product at Rdio.

Rdio's challenges go well beyond integrating radio. But most of its problems would be easier to solve if its user base was growing rapidly. If the Cumulus integration gets Rdio there, it will have been well worth it.