Music Anywhere is not a new concept. Many companies past and present have offered similar services and historically this has resulted in a number of legal challenges, for example:

• MP3.com ran into serious legal trouble back in 2000 for providing a service called "Beam-it", which allowed users to upload tracks to servers at my.MP3.com for access anywhere. A US judge in UMG v. MP3.com ruled that by running the service, MP3.com had illegally duplicated almost every digital recording ever made. The result was $53m in fines which pushed the company to the brink of insolvency. It eventually merged with Vivendi Universal.

• US company imeem similarly allowed users to share playlists of music uploaded from their hard drives. Imeem struggled with legal issues, including an uneasy relationship with Warner Music. These ended with imeem turning off the upload functionality once it made deals with the majors and only allowing the use of songs from the licensed catalogue. The ad-supported model fell far short of bringing in enough money to pay licence holders. imeem was absorbed by MySpace in 2009

Carphone Warehouse's offering is likely to bring up legal questions similar to the ones that have wrecked previous cloud music services. The difficult point is the copying and redistribution of music not in the licensed catalogue. At present however, the service seems to have the support of the four major music labels, The Orchard and various independents.

Music Anywhere's offer of unlimited online storage is unusual. The company's large catalogue combined with decent recognition software should minimise the number of unrecognised tracks, and so limit the amount of server storage. However, if the recognition software isn't effective, operating costs will soar. By contrast other similar services tend to avoid the possibility of users uploading a theoretically unlimited numbers of tracks, and reducing their exposure to storage costs and legal challenges, for example:

• mSpot similarly allows streaming of a user's PC-based music through an android device. The free version has a maximum online cache of 2GB, enough for about 1,600 tracks, more storage can be purchased.

• nuTsie is another similar free service. nuTsie can only store and playback tracks that it has in its own catalogue and it plays playlists rather than tracks on-demand, but it doesn't have a limit on the number of tracks a user can 'upload'.Didiom allows live music streaming from a user's PC to a mobile device, provided the PC is online. The service costs $0.99 per month or $9.99 per year.Apple also has an equivalent, albeit largely unpromoted, feature as part of its 'MobileMe' suite of services. As part of their $99/£59 per year subscription users can stream music from their 20GB of storage on Apple's servers through the iDisk app.

It's debatable to what extent potentially unlimited cloud storage gives Carphone a competitive advantage. SD cards are cheap and high capacity storage often comes free with high-end phones. In addition, mobile data caps and patchy 3G coverage are likely to seriously threaten the user experience. The 500 track limit on the number of tracks that can be stored on a user's phone is unlikely to be sufficient for the heavy users Carphone Warehouse is targeting with this service.