UPDATE 2-Polycom sees Q2 revenue below Wall Street estimates

(Recasts; adds details from conference call)

April 16 (Reuters) - Polycom Inc (PLCM.O: Quote, Profile, Research), a maker of video conferencing products, posted a 39 percent rise in first-quarter profit as revenue jumped helped by an acquisition, but the results fell short of Wall Street estimates.

The company also forecast second-quarter revenue below market expectations. In a conference call, Polycom projected an increase of 2 to 3 percent in revenue from the previous quarter, citing a growth in demand for its high-definition products.

However, the forecast implies a revenue of $264.1 million to $266.7 million, which is below analysts' average estimate of $269.9 million.

The company also said it expected gross margin to decline by about one percentage point during the period.

Polycom, which competes with Norwegian rival Tandberg (TAA.OL: Quote, Profile, Research), is looking to gain from the rapid growth of its high-definition product lines and investments made by companies to reduce business travel costs.

First-quarter net income rose to $14.2 million, or 16 cents a share, from $10.2 million, or 11 cents a share, a year earlier. Excluding items, it earned 36 cents a share.

Revenue rose 34 percent to $258.9 million, boosted by the contribution from SpectraLink. SpectraLink, which the company acquired last year, contributed $39.4 million.

Analysts expected earnings of 37 cents a share, excluding special items, on revenue of $261.8 million, according to Reuters Estimates.

Shares of Polycom fell 2.4 percent to $22 in trading after the bell. The stock closed at $22.53 Wednesday on Nasdaq. (Reporting by Purwa Naveen Raman in Bangalore; Editing by Deepak Kannan, Himani Sarkar)