It’s no secret that much of the business won by over-the-top service providers is at the expense of facilities-based operators. Service development platform provider Teligent (News - Alert) Telecom aims to stop – or at least stem – that movement by supplying telephone companies and other facilities-based entities with its SDP and related prepackaged applications.

The company this week at Mobile World Congress (News - Alert) in Barcelona was promoting its prepackaged application called VoIP Zone.

Ulf Lindsten, Teligent Telecom’s vice president of business development, explains that VoIP Zone was designed to help wireless service providers offer a mobile VoIP client to compete with similar offers from such companies as Skype (News - Alert). Rather than losing the customer entirely to Skype, says Lindsten, why not offer a lower-cost, more competitive mobile calling option.

“Instead, we’re saying ‘stop losing it, keep some of it,’” adds Lindsten.

And the Teligent Telecom mobile client allows mobile operators to deliver a more attractive option than does Skype, he says, because end customers can keep their existing phone numbers, and don’t need to set up new accounts.

“Given Skype’s enormous traffic volumes, it’s difficult not to conclude that at least some of Skype’s growth is coming at the expense of traditional carriers,” says TeleGeography (News - Alert) analyst Stephan Beckert. “If all of Skype’s on-net traffic had been routed via phone companies, global cross-border telephone traffic would have grown 13 percent in 2011, remaining in line with historical growth rates.”

A press release on TeleGeography’s website estimates cross-border Skype-to-Skype calls (including video calls) grew 48 percent in 2011, to 145 billion minutes. “Although the volume of international traffic routed via telephone companies remains more than three times greater than Skype’s cross-border volumes, their growth rates differ dramatically,” according to the research firm. “TeleGeography estimates that Skype added 47 billion minutes of international traffic in 2011—more than twice as much as all the telephone companies in the world, combined.”