Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Sonus Networks (Nasdaq: SONS) fell more than 15% in intraday trading after the company reported disappointing third-quarter results last night. Revenue slumped 24%, leading to an $0.08-per-share loss. Analysts had expected Sonus to break even.

So what: Sonus Networks supplies equipment for enabling Voice over IP services such as those provided by Vonage and Skype.

Now what: Poor results from Sonus don't necessarily portend bad tidings for VoIP. Acme Packet (Nasdaq: APKT) also supplies VoIP infrastructure equipment yet is thriving. Sonus may have failed to find a niche for competing against larger, better-recognized peers Cisco (Nasdaq: CSCO) and Juniper Networks (Nasdaq: JNPR).

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Fool contributor Tim Beyers is a member of the Motley Fool Rule Breakers stock-picking team. He didn't own shares in any of the companies mentioned in this article at the time of publication. Check out Tim's portfolio holdings and Foolish writings, or connect with him on Twitter as @milehighfool. You can also get his insights delivered directly to your RSS reader. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has written a bull call spread option position in Cisco and is also on Twitter as @TheMotleyFool. Its disclosure policy is at least 10% better than other disclosure policies.