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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