AT&T, CenturyLink, NTT, Telstra, Verizon and Windstream were the top six cloud investors in 2011 as North American and Asian telecom operators accounted for 90 percent-about $12 billion-of cloud investments in 2011, according to new research.

Informa Telecoms and Media said European operators, led by Deutsche Telekom, Orange, Portugal Telecom and Telefonica, accounted for just seven percent, about $945 million, of the global total committed to cloud assets during the same period.

"European operators are being outgunned in cloud infrastructure," said Camille Mendler, principal analyst at Informa. "Although they are working to stimulate local demand, their investment strategy remains cautious."

Some 127 operators around the world launched an average of one cloud service every other day, a total of 170 new services, in 2011. In 2010, just 80 operators were active in cloud services. There were five primary services that accounted for 70 percent of all launches, Informa said: infrastructure as a service, storage, unified communications, business productivity applications and security.

In general, Informa said, North American operators are acquiring client bases and assets at home and abroad, while European operators focus on launching services at home. Asian operators, meanwhile, are pursuing a blended strategy of infrastructure investment and service launch nationally and internationally. Meanwhile, Latin American, Middle Eastern and African operators are building up domestic infrastructure and competences.