The suit was filed in the district court of Eastern Texas, which is renowned for handling technology patent disputes and is currently the focus of a feud between Microsoft and i4i.
Klausner alleges that both Cisco and Avaya VoIP solutions have infringed on its visual voicemail patents covering features through which subscribers can selectively retrieve messages from mobile devices and PCs.
MicroScope understands the mysterious Klausner Technologies,which is owned by PDA and electronic organiser pioneer and inventor Judah Klausner, does not appear to provide any solutions or services itself; it merely serves as a holder for 25 patents.
Its equally uninformative website provides no clues to the privately held firm's corporate background or any actual information, merely a series of email addresses for licensing enquiries.
This is not the first time Klausner has struck, having previously successfully settled with Apple, AT&T, Citrix, Google, LG, and Vonage among others,over similar issues.
Cisco and Avaya have not commented publicly on the spat.