Sprint kicked off 2008’s telecom patent litigation festivities this week by suing four small telecom companies for violating six of its patents.

In court documents filed with the US District Court in Wichita, Kan., this week, Sprint alleged that Paetec Holding, Broadvox Holdings, Big River Telephone Company and Nuvox all infringed upon its patents for virtual connections systems.

Three of the patents (numbers 6,343,084, 6,298,064 and 6,473,429) describe a system for providing virtual connections through an ATM interworking multiplexer on a call-by-call basis. The remaining three patents (numbers 6,463,052, 6,452,932 and 6,633,561) concern a communications control system where “signaling is processed externally to a switch before it is applied by the network elements.”

The six patents, which are part of Sprint’s voice-over-packet (VoP) services portfolio, are the same patents that Sprint used to successfully sue Vonage to the tune of an $80 million settlement. Under the terms of that settlement, Vonage agreed to pay Sprint-Nextel $40 million for a fully paid future license to use its VoP services portfolio, $35 million for past use of the VoP license, and $5 million in prepayment of services. Prior to the settlement, a Kansas jury found Vonage guilty of infringing on six Sprint-Nextel patents and awarded Sprint $69.5 million in damages.

“We view this settlement and licensing agreement as a validation of the strength and breadth of our patent portfolio,” said Harley Ball, Sprint Nextel’s vice president of intellectual property, at the time. “This is an affirmation of Sprint’s research and development and a testament to the rich history of innovation at Sprint Nextel.”