French telecom group Orange SA has been sued in California by San Francisco-based startup Telesocial over an application that lets users make phone calls via their Facebook profiles, the Financial Times reported.

Telesocial claims that the PartyCall app, launched in November 2012 by Orange, was based on its own code that it shared with the company during negotiation of a deal that the telecom carrier later dropped, the FT said. (on.ft.com/1BVpkf3)

Telesocial's complaint included server logs that it claims show several Orange employees gaining unauthorized access to its servers to "copy and reverse engineer Telesocial's proprietary application and related technologies."

Telesocial did not immediately reply to an email requesting comment. Orange could not be reached for comment outside of regular business hours.