It's hard to predict the kind of impact the new Apple (NASDAQ:AAPL) iPhone will have on competitors and the market overall. The wireless business and consumer tastes around the world make the task of coming up with a winning strategy extremely complex. But the next generation (3G) iPhone has already laid waste to a supporting partner and active participant in the smartphone space -- Synchronoss Technologies (NASDAQ:SNCR).

Synchronoss rose to glory following its IPO in 2006 by inking several deals with companies such as Clearwire (NASDAQ:CLWR) and Time Warner Cable (NYSE:TWC) to provision and support activations of new wireless devices. But the deal that outshone all the others was the contract with AT&T (NYSE:T) to provide the software service that performed the at-home activation function during the much-hyped initial release of the iPhone.

With millions of iPhones being snapped up over ensuing months, Synchronoss' revenue and cash flow soared -- along with the stock. Investors saw international markets potentially fueling even more growth, but there was a hitch -- 78% of Synchronoss' revenue in the third quarter last year came from AT&T.

Synchronoss has made great strides in diversifying its customer base, but the revenue concentration for iPhone provisioning has stuck with the company. Caught digging through its recent 10-Q, fellow Fool Rich Smith pointed out that Synchronoss is still heavily dependent on AT&T, with 72% of first-quarter 2008 revenue coming from the carrier.

Now that Synchronoss has admitted in an 8-K filing that it will not participate in the on-site retail stores' activations of 3G iPhones, investors are bailing fast. The stock dropped around 17% on Tuesday, and that follows the more than 62% decline shares had already seen since the beginning of the year.

The lesson is simple: Companies that receive an overwhelming portion of their revenue from one source are especially risky and volatile. Yesterday's helium can quickly become today's cement shoes -- in other words, when times are good, revenue concentration makes you look like a star, but when times are bad, you're "sleeping with the fishes."

While some see the fall as a great buying opportunity, the full impact of Synchronoss being left out of the next iPhone game is not certain. For certain, until other customers such as Vonage (NYSE:VG) and Level 3 (NASDAQ:LVLT) make up a larger portion of revenues, the company's fortunes will change dramatically as the iPhone grows up.

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