If you believe the revenue estimates of Juniper, the value of mobile music was worth $3.1 billion in 2010 and will rise to $5.1 billion in 2015. In fact, mobile is so important to digital music that it is "propping up a failing industry hit by over a decade of widespread online piracy," according to its press release.

And where is all that revenue coming from? Legal distribution services "such as iTunes" are now "blossoming," says Juniper.

Frankly, $3.1 billion is a pretty high estimate. Consider that the global digital market - not just mobile, but the entire digital market - was worth $4.6 billion in 2010, according to the IFPI's Digital Music Report 2011. If Juniper's estimate of the 2010 global mobile market is correct, that means mobile accounted for about 67% of all digital music last year.

But let's give Juniper the benefit of the doubt for a second. Let's assume it meant that consumer spending on mobile music services amounted to $3.1 billion. Since the IFPI's figure is for trade value, and since downloads seem to be the basis for Juniper's revenue estimate, let's calculate the retail value of the IFPI's $4.6 billion figure. Divide $4.6 billion by a typical 0.7 (out of every dollar) rate paid to rights holders for digital downloads and you get $6.5 billion in consumer spending. Using this adjusted IFPI number, Juniper is effectively saying mobile accounted for 47% of global digital music spending.

Long story short: Mobile is full of potential and hope but is not yet a truly strong revenue source.

Here's the longer version: Mobile music may struggle to be the revenue source Juniper -- and many others -- expect it to be. Thus far, mobile music has been a challenging learning experience. Beyond ringtones, which are declining, no other mobile product has really connected with mainstream consumers.

Instead of blossoming mobile downloads, what mobile trends are most readily apparent? There are two. First is the rising popularity of Internet radio. In the U.S., Pandora is the lone killer mobile app. Nothing else comes close. And while it has a large market share, Pandora (on all types of devices) and its peers do not represent the large music revenue source that will push revenues to $5.1 billion. Non-interactive royalties won't get us there.

The other trend is one that transcends the music business: from video to newspapers, digital delivery gives consumers more entertainment options for less money. Fewer people are buying music, says NPD's Russ Crupnick http://www.digitalmusicnews.com/stories/022411dmfe1. The casual consumer is exiting the building. Is it any wonder? Mobile (and PC-based) consumers have many music options (both legal and illegal) that do not require spending money. And if consumers do start to adopt subscription services in large numbers, they will reduce their download purchases - there won't be simultaneous growth in both areas.

Finally, growth in mobile music is tied to the PC and living room. Some gains in mobile services can be considered gains in PC-based services that also offer apps for connected TVs. That's because mobile is just one facet of today's - and tomorrow's - music services.