Sony is going up against Spotify by releasing its first Music Unlimited app for iPhone offering Apple users a streaming catalog of about 15 million songs this week, CNET reported.

The Music Unlimited app will launch by the end of the week after debuting more than 12 months ago on Sony devices.

At CES 2012, Sony initially announced the app would be released in summer.

The Music Unlimited app is only iPhone and iPad at the moment. Spotify released its official iPad app last month.

Other devices that currently feature Music Unlimited include Sony Bravia TVs, PlayStation 3, PlayStation Vita, and Android tablets, and smartphones.

In January 2012, Sony said it had 1 million active Music Unlimited customers, while Spotify is estimated to have up to 18 million monthly users. Both Spotify and Music Unlimited lay claim to libraries of more than 15 million songs.

At CES, Sony Network Entertainment President Tim Schaaff said cloud-based services are still "in an early stage of competition," and that Sony is "getting its skin in the game."