LONDON (Reuters) - Pan-European network operator Interoute plans to offer a Skype-type free Internet-based voice calls service to corporations, hoping to replicate Skype's success in the business market and expand its core data business.

Skype, owned by online auctioneer eBay Inc, has in three years built up a base of around 75 million users who use its software to make free calls from their computer to another computer anywhere in the world.

Interoute said on Tuesday its iSiP service, which like Skype uses the Voice over Internet Protocol (VoIP) technology, will also allow companies to offer free Internet calls, free national calls and cheaper calls to mobiles, but without any security concerns.

Companies are increasingly adopting VoIP, in which a voice call is broken up into data bits and carried over the Internet, to cut communication costs, but have shied from embracing some of the cheaper and popular consumer applications for fear it could expose their networks to hackers and viruses.

"iSiP is like Skype without the 'Skypemares'," Interoute's Executive Chairman James Kinsella told Reuters, adding that it could be safely deployed by companies as corporate IT departments would have full control over its use.

Companies could use the service to cut communication costs with their staff, customers or suppliers anywhere in the world. Interoute plans to offer iSiP for a flat fee of 1,500 pounds ($2,620) a month to companies, with no limit on the number of users.

Kinsella said Interoute, which is controlled by the Swiss-based Sandoz Family Foundation, was hoping to get existing customers to spend more and sign up new business with the new service.

Unlike some of the traditional telecoms companies, Interoute said it had no voice revenues to protect and it hoped to use its cheap voice calls service to sign up more corporations for its data services.

"For us voice is also data. That's our pitch to customers," said Kinsella, the man who sold Dutch Internet service provider World Online -- another Sandoz investment -- near the market's peak in 2000.

Interoute, which posted revenues of 86 million euros in 2005, was taken into administrative receivership by key French creditor and supplier Alcatel and emerged from administration three years ago.

The firm runs a 30,000 km (18,750 mile) long network that stretches from New York to Bratislava and Stockholm to southern Italy, connecting 61 cities in 19 countries. The firm counts planemaker Airbus and the Italian military among its roughly 14,000 customers.