Cisco Systems reported a decline in orders among U.S. service providers in the quarter ending in April but insisted it was a temporary phenomenon.

Though orders from service providers--typically about a quarter of Cisco’s overall business--were up 6% from a year ago in the quarter, those from U.S. service providers were down 3%.

Those orders may have been dragged down in part by a slowdown in orders from cable operators for Cisco’s Scientific-Atlanta set-top equipment, according to Simon Leopold, an analyst for Morgan Keegan. And that relative slowdown is partly the result of regulatory changes, according to Cisco, which characterized the trend as a return to normalcy for SA.

The year-ago quarter, which ended in April 2007, came shortly before the FCC’s July deadline mandating separable security for set-tops. So the removable security cards Cisco was selling to help operators meet that deadline reached its peak a year ago and began to drop off in the quarter ending last July.

Following the year-over-year decline in SA’s orders reported this week, Cisco expects a year-over-year revenue decline next quarter, the vendor said.

Orders for Cisco’s core routing platform, the CRS-1, were up 150% from a year earlier, with domestic customers including AT&T and XO Communications.

“I’m not aware of any of our large peers that have numbers like that with their flagship products,” Cisco CEO John Chambers said. Though that comment was made in response to an analyst’s question about how Cisco is doing in the service provider space relative to its chief rival, Juniper Networks, it also seemed like a return volley to recent comments made by Juniper’s CEO, Scott Kriens.

During a quarterly earnings call last month, Kriens pointed out that Juniper had sold 105 of its new T1600 core router platform in its first full quarter of availability. “This compares quite favorably with our competitor’s claim of 100 units [sold] after only a full year of customer testing,” he said.

On this week’s call, Chambers reiterated that it takes a while for customers to trust the CRS-1 well enough to let it handle their core traffic.

And he called the company’s weakness among North American service providers “a cycle” that would probably last one or two quarters, followed by fiscal-year growth in the mid teens or higher.

“Our relationship with global service providers and where they see Cisco’s relevance is improving almost without exception, be they fixed or mobile,” Chambers said. “Who would have said just two years ago that an AT&T and a Verizon and a BT would all say, ‘Cisco, you have the potential to be my best business partner as well as my best technology partner, not just on one technology but on all fronts?’”