It may be one of the biggest success stories in communications history, enjoying almost iconic popularity but for enterprise users, Skype remains an unwelcome visitor.

This is the conclusion of a report by analyst firm, Current Analysis which points to the Voice over IP (VoIP) firm’s perceived weakness in security making the software an untenable risk for most enterprises.

The report: `Skype’s love-hate relationship with enterprises,’ examines the reasons behind enterprise managers’ reluctance to allow installation of the software on workers’ PCs. The analyst firm says that while Skype far outperforms its rivals in both quality and its take-up – up to 200,000 new customers a day, compared with an average competitors’ 20,000 in a week – it remains “to carriers what Napster was to the music industry”.

However, Skype’s proprietary supernode peer-to-peer (P2P) architecture presents a serious conundrum to enterprise managers. “Skype says it’s perfectly safe” says report author Dustin Kehoe, senior analyst at Current Analysis, “but that means they [customers] have to take Skype at their word.”

A lack of open standards was also cited in the report as being of serious concern for enterprise customers but it is security that troubles enterprises most about the champion of VoIP. “Skype has and is trying,” says Kehoe, “they try to be as open and honest about security issues as possible and are actually very transparent. It says, for example that if you are behind a firewall they won’t turn you into a supernode but again, you only have their word for it.”

Asked if Skype could bring out a beefier, more secure version suitable for enterprise customers, Kehoe says “no, if you are going to use Skype you have to accept that it uses P2P technology”.

Within the course of three years, Skype has achieved a base of 120 million users with zero acquisition costs but only a quarter of those customers are business users. The report cites the global telecom user group, The EVUA , which found that 69 per cent of its member corporations do not support Skype and prohibit users from installing it. Only 6 per cent said they were likely to change that.

Despite repeated requests, Skype refused to comment.