After successfully suing Microsoft for similar infringements, patent holding company VirnetX is taking Apple to court over the iPhone, iPad, and iPod touch, suggesting that Apple's VPN implementation violates two of the company's VPN-related patents. Also named in the lawsuit, filed in Eastern Texas US District Court, are Aastra, Cisco, and NEC.

VirnetX originally sued Microsoft in 2007 after VirnetX acquired a number of patents from defense contractor Science Applications International in 2006. The company alleged that Microsoft Office Communicator and Windows Meeting Space each infringed one of two of its patents, including US patents 6,502,135 "Agile Network Protocol for Secure Communications with Assured System Availability" and "Method for Establishing Secure Communication Link Between Computers of Virtual Private Network."

VirnetX won the trial in March this year, with the jury awarding the company $106 million. Microsoft appealed, asserting that the patents were invalid, but later in May settled with VirnetX for $200 million, avoiding additional legal fees and potential treble damages. In June, the US Patent and Trademark Office confirmed both patents as valid after a lengthy review initiated by the lawsuit.

With the confidence of a legal victory and affirmation from the USPTO behind it, VirnetX is now alleging that Apple's mobile devices infringe at least some claims of the '135 patent as well as several claims of US patent 7,490,151 "Establishment of a Secure Communication Link Based on a Domain Name Service (DNS) Request."

The claims against Aastra, Cisco, and NEC mainly target their VoIP products, including servers, software, and VoIP phones. A number of Cisco's IP routing products with VPN capabilities are also accused of infringing VirnetX's IP. In addition to the '135, '180, and 151 patents, the company claims one or more of the products named in the suit infringe on US patents 6,839,759 "Method for Establishing Secure Communication Link Between Computers of Virtual Private Network Without User Entering Any Cryptographic Information" and 7,418,504 "Agile Network Protocol for Secure Communications Using Secure Domain Names."