Ringtones are big business. The Yankee Group announced that over the last five years, these musical tones have sent people literally singing to the bank, with a total revenue of $2 billion since 2001, and $50 million in one year alone.

The figures show how popular ringtones have become among cell phone users, who download the files to personalize their caller functions. They can pick from millions of songs, from the latest hit R&B single, to quirky sounds like cows mooing, to the classical pieces of Ludwig van Beethoven. Technological development has also made the audio quality of the ringtones much more realistic. From the ear-piercing, tin-like sounds of the first downloadable tunes, todays music pieces have a near-radio quality. You could dance to it, except youd look pretty silly shaking your booty while taking a call.

Unfortunately, the realistic quality of the musical pieces have raised a few ethical issues, namely violation of copyright. Since the sound of the ringtones and the sound of the actual songs are so close, record companies are saying that they count as reproductionsand because of that, they should pay some kind of royalty to the labels and the singers.

In a celebrated case, rap artist Eminem filed injunctions against five ringtone companies, supposedly because they had used his songs without his prior consent.

Some would argue that the ringtones only use ten seconds, maximum, of the actual song. How long should a snippet be before it becomes copyright infringement? Nokia representative Matthew Courtney believes that it has nothing to do with length. "Every reproduction of a musical excerpt involves payment of copyright fees to the copyright owner," he says.

There are some songs that fall beyond this rule, such as those that fall into public domain: classical pieces, national anthems, and yes, a cow mooing. (To date, there are no records of cows suing any major ringtone company.) Others still require the permission of the artists, and may even be subject to royalty fees.

Luckily most artists are not that inclined to sue, seeing the ringtones as a way of promoting their music, and perhaps a compliment to their own popularity. In a way, being immortalized in a ringtone has become a gauge of how ones music has infiltrated public consciousness. Besides, nobody actually downloads a ringtone as a replacement for an actual record. A real fan would want more than a ten second recording out of a three minute song, although would probably use that snippet to announce to the world, Hey, this tune rocks.

However, trends do indicate that fans may actually be willing to pay for their polyphonic ringtones. Music label EMI representative Jay Samit estimates that the earnings form ringtones could contribute as much as 10% of the record industrys total revenues. Apparently, the appeal of ringtones is that strong people arent just downloading it because its free, but because its a valued feature.

Of course, many polyphonic ringtones still allow people to download the tunes for free, generating their revenue from ads instead. Others use a mixture of the two business models, offering some for free (or a weekly rotating list) while requiring a small download fee for premium ringtones.

Either way, lawsuits notwithstanding, the fact is that ringtones are here to stay.