Apple has not yet offered a cloud-music service on its own, but a new app available in the App Store hopes to fill that void.

The mSpot music app lets users store up to 2GB of compressed music files in a cloud-based locker, and then stream it to their iPhone or other Internet-enabled devices. It's the same app the company released for the Android back in June, but this time approved for the iPhone.

Users who want more than 2GB can pay $4 a month for 40GB. The size of storage is important because of how mSpot goes about offering this service without music licensing deals. See, this is a true music locker, in which users must transfer copies of their digital music files to the cloud for storage, and then stream from there.

Other music locker services simply scan the song titles in their users' libraries and then match them against a cloud-based server to give access only to songs with a match. There's no transfer of files necessary and the provider needs only host one copy of each song.

In mSpot's case, it actually hosts multiple copies of the same song in each users individual locker. Label sources speaking to Billboard about cloud services in the past have expressed uncertainty over whether they have the legal standing to demand extra payment for this kind of model. It's certainly more expensive of a service to provide, given the need to maintain servers and son on.

mSpot claims more than a million downloads of the Android version of the app and 500,000 registered users, but won't detail how many of those are in active use.