ADC Telecom blamed uncertainty over the pending AT&T/BellSouth merger in part for some missed revenue in its recent quarter and low visibility in the current quarter.

The equipment vendor this week projected its fiscal first-quarter revenue (for the quarter ending Jan. 31, 2007) to drop 15% sequentially (to about $261 million) due to uncertainties created by the pending merger of its customers and other factors. In addition, its second-quarter sequential revenue increase may be lower than normal, ADC said, depending on when these uncertainties are resolved.

“Our near-term visibility…remains cloudy due primarily to market uncertainties,” ADC said in a statement issued Tuesday. “These…include how long it will take our customers to reduce current excess FTTX inventory levels as well as how long and to what degree spending by our customers will be deferred during regulatory reviews and integration of customers' mergers. Regulatory reviews involve both consolidation of significant customers in the United States and the deployment of FTTX networks outside the United States. The timing and extent of our growth opportunities are unclear until these uncertainties are resolved."

Though revenue from ADC’s broadband infrastructure and access group were up 2% from a year earlier to $255 million in the fiscal fourth quarter, it was down 13% sequentially, which ADC attributed partly to “merger activity among customers that ADC believes reduced demand for copper products to support central office infrastructure and access deployments.”

Revenue from professional services, which was up 3% sequentially and 17% from a year earlier to $52 million, was negatively affected by merger activity among U.S. customers, ADC added.

Several equipment vendors, including Alcatel-Lucent and Cisco Systems, wrote letters to the Federal Communications Commission on Friday, urging the FCC to conclude its review of the proposed acquisition of BellSouth by AT&T. In its letter, Cisco said the FCC’s delay in reviewing the merger “has adversely affected broadband network investment by both [carriers] and Cingular Wireless,” which the two carriers co-own.

Tellabs CEO Krish Prabhu made similar comments earlier this month.

The FCC will meet again publicly on Dec. 20. It’s unknown whether the FCC will conclude its review of the merger at that time.