Privately held Concerto Software is to acquire Aspect Communications in a deal valued at US$1 billion that could create the world's largest call center products and services company, the pair said Tuesday.

The duo are hoping the tie-up will better position them to expand their presence in countries where call centers are rapidly growing, notably Latin America, India, the Philippines and China.

Under the terms of the agreement, Aspect shareholders will receive US$11.60 in cash for each share of common stock, equal to a roughly 15 percent premium over Aspect's average closing price for the last 30 days, the companies said. The merger is valued at about US$1 billion.

Aspect's board of directors has already approved the merger and deal is expected to close as early as September, subject to the approval of Aspect's shareholders and regulators. Once the deal has closed, Aspect will cease to be traded as a public company. The new combined firm will be privately held by Concerto's investors -- Golden Gate Capital and Oak Investment Partners -- and management. Heading up the combined company as president and chief executive officer (CEO) will be James Foy, Concerto's current president and CEO.

In a press release announcing the deal, Aspect released preliminary results for its second financial quarter, ended June 30, which lagged the company's previous forecasts somewhat. Back in April, the company had predicted revenue of between US$90 million and US$92 million, operating income in the range of US$10 million to US$11 million and earnings per share of US$0.08 to US$0.10. Instead, on Wednesday, Aspect estimated preliminary second quarter revenue in the order of US$85 million to US$86 million, operating income between US$7.5 million and US$8.5 million and earnings per share of US$0.06 to US$0.07. The initial results include around US$4 million in restructuring costs relating to the consolidation of office space, Aspect said in the release.

Concerto specializes in outbound dialing and unified call center software, while Aspect focuses on call center workforce management application and performance analytics. Concerto has more than 2,300 customers, while over two thirds of the Fortune 50 are Aspect customers.