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: Sonus Networks (Nasdaq: SONS) dropped 18% in intraday trading today after first-quarter EPS of $0.04 fell short of the consensus forecast of $0.00.

So what: Revenue of $67.3 million increased 8% from the year-ago quarter, with 53% of revenue coming from Bahamas Telecom. Management said that reselling a substantial amount of third-party equipment to Bahamas Telecom pressured gross margins but would not continue.

Now what: The company is restructuring, changing its go-to-market model and refreshing its senior management team. The outsized influence of a single customer on first-quarter results adds to the high level of risk in Sonus' business. While change is clearly necessary to improve financial results, it is far too soon to tell if this turnaround will really turn.

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Fool contributor Cindy Johnson does not own shares of any company named above. 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 a disclosure policy.