Wireless technologist InterDigital (Nasdaq: IDCC) has a remarkably steady business model in many ways -- but shockingly jumpy cash flows.

This quarter, the company reported decent earnings of $0.15 per diluted share on sales of $56 million. These numbers compare unfavorably to the year-ago figures, mostly because of a large one-time payment from handset manufacturer Sony Ericsson, a joint venture between Swedish communications expert LM Ericsson (Nasdaq: ERIC) and Japanese electronics giant Sony (NYSE: SNE).

Without such a sudden influx of capital this time around, $55.5 million of the total sales were recurring payments on long-term technology license royalty contracts, which is why InterDigital's sales curve is so smooth in the long term. Major customers like Samsung, Apple (Nasdaq: AAPL), and Research In Motion (Nasdaq: RIMM) simply need the company's wireless transfer technologies in order to make and sell their iPhones, BlackBerrys, and so on.

Free cash flow took a flying leap off a mountaintop, to the tune of $77.7 million. Yes, higher than net income by a mile, but also bigger than the quarterly sales. This has become somewhat of a tradition in InterDigital's first fiscal quarter, as the 2007 figure was $93.3 million on net income of just $17.7 million.

The reason lies in InterDigital's cash management practices. This time, the company appears to have collected on a large amount of outstanding invoices, as the accounts-receivable line dropped from $130.9 million last quarter to just $38 million now. Meanwhile, the balance of cash equivalents increased by $67 million to a healthy $240 million.

Hey, I'm not complaining -- the occasional shot of extra cash never hurts, and perhaps the company can put the new assets to good use by upgrading its research department or by marketing its promising SlimChip technology more aggressively.

Either way, it's decent news all around, and even better in the cash flow department. Keep it up!

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Fool contributor Anders Bylund holds no position in any of the companies discussed here. You can check out Anders' holdings if you like, and Foolish disclosure always ensures a clear signal.