Juniper Networks Inc. reported preliminary estimated third-quarter results that missed its own forecast, citing lower-than-anticipated demand from service providers, particularly in the U.S.

Revenue is projected to be $1.11 billion to $1.12 billion, less than Juniper’s own estimate of $1.15 billion to $1.2 billion, the Sunnyvale, California-based company said in a statement Thursday. Adjusted earnings per share will be 34 cents to 36 cents, compared with its earlier 35 cent to 40 cent- projection.

The shares slumped as much as 6.2 percent to $19.64 in extended trading after the company’s statement. They had declined 1.2 percent at the close in New York.

Juniper’s business is being hurt as some telecommunications carriers delay equipment purchases for the rest of 2014. It has also struggled to sell smaller gear to corporations, a market dominated by rival Cisco Systems Inc. The stock slumped the most in almost three years on July 23, after the company gave its forecast for third-quarter results, which trailed analysts’ estimates.

Juniper will release full preliminary third-quarter results on Oct. 23.