In a Monday statement, VOIP provider Fring said that it was being forced to close down its compatibility with Skype due to a threat of legal action from the company – a move that Fring calls an “anti-competitive ambush” by Skype.

In a statement, Fring said: “Since its foundation in 2006, Fring's rich mobile communications have been available to both Fring users and open 3rd party networks including GoogleTalk, SIP, Twitter, and, until now, Skype. However, despite Fring expanding its network capacity over the last days to serve its enlarged user base, Skype is refusing to allow Fring to restore connectivity to Skype.”

Fring further added that though the blocking of the service by Skype will affect the desired communication of Fring users with their Skype friends; the users can still invite their Skype friends to join Fring.

While Fring claims to have been offering interoperability in accordance with the Skype protocol since 2006, Skype has confirmed that Fring was “in breach of Skype’s API Terms of Use and End User License Agreement”; and adding that “developers that do not comply with our terms will be subject to legal enforcement.”

In addition, Skype also mentioned that the issue was still under discussion by the two companies; and that Fring was lying about being blocked. Skype further added that Fring itself “withdrew support for video calls over Skype on iOS 4 without warning.”