Dan Farber/CNET

Beats Electronics, the headphone company founded and run by music industry legend Jimmy Iovine, has joined up with AT&T to launch its subscription music service on January 21.

Everyone can try the entire service for free, Beats Music said, AT&T customers can access unlimited song streaming and downloads for individuals across three devices for $10 a month or for up to five family members across 10 devices for $15 a month. AT&T Family customers will receive a 90-day free trial, while individual AT&T wireless customers can get the first 30 days free. It will be part of an AT&T customer's regular bill.

Song downloads will allow customers to listen to music when they're offline, but a download expires when the user's membership ends.

Beats Music will be available for download on nearly all major platforms or from a PC beginning January 21, the companies said. It's supported on iPhone, Android, or Windows Mobile phone.

CNET reported in July that Beats was pursuing a partnership with AT&T to launch its music service.

Striking a deal with AT&T, the country's second-biggest wireless carrier, gives Beats a huge pool of potential customers and a mega marketing machine at its very outset, with single billing removing the hurdle of entering in payment information to sign up as a revenue-generating subscriber.

It's a strategy that some of Beats Music's main rivals -- the likes of Spotify and Deezer -- have used to spread their service globally.

While Beats is entering a market of strong growth, it's also one of intensifying competition. Not only is Beats going up against relative newcomers like Spotify, it will also face entrenched Internet radio service Pandora and offerings from huge tech companies such as Apple's iTunes Radio and Google's All Access.

Beats is seeking to set itself apart by marrying algorithms with curated programming from tastemakers. In a blog post Saturday, Beats Music CEO Ian C. Rogers said Beats Music's competitors "aren't actually 'services,' they're 'servers.'"

Beats Music combines "the trust that comes from excellent handpicked music with the personalization that knows you're an individual and that a handful of stations can't satisfy all listeners," Rogers said.

Iovine founded Beats with musician and producer Dr. Dre and bought MOG, an on-demand subscription service. The intent was to combine that technology and the Beats brand to create Beats Music, also known by its code name Daisy.

Update, 1:47 p.m. PT: Adds details from blog post.