The Patent Trial and Appeal Board (PTAB) has ruled in favor of Cisco Systems Inc., invalidating all challenged claims of a Portsmouth Network Corporation patent related to content delivery over a network. The PTAB determined that the claims were unpatentable due to obviousness.
This decision stems from an inter partes review (IPR) initiated by Cisco on January 30, 2024, targeting U.S. Patent No. 6,917,986, which is owned by Portsmouth Network Corporation. The PTAB instituted the review on August 6, 2024, and issued its final written decision on August 4, 2025, concluding that the challenged claims were unpatentable. ([insight.rpxcorp.com](https://insight.rpxcorp.com/ptab/16858-cisco-systems-v-portsmouth-network-corporation-ipr-of-986?utm_source=openai))
Portsmouth Network Corporation, a non-practicing entity, had previously asserted this patent against Cisco and other companies, including Juniper Networks. ([unifiedpatents.com](https://www.unifiedpatents.com/insights/2024/4/27/portsmouth-network-corp-communication-patent-challenge-instituted?utm_source=openai))
In a related development, Unified Patents filed an ex parte reexamination request against another Portsmouth patent, U.S. Patent No. 8,014,394, on March 5, 2024. The Central Reexamination Unit granted this request on April 19, 2024, finding substantial new questions of patentability regarding the challenged claims. ([unifiedpatents.com](https://www.unifiedpatents.com/insights/2024/4/27/portsmouth-network-corp-communication-patent-challenge-instituted?utm_source=openai))
These proceedings highlight the ongoing legal challenges faced by technology companies in defending against patent assertions by non-practicing entities. The PTAB’s decision in favor of Cisco underscores the importance of inter partes reviews as a mechanism for contesting the validity of patents in the technology sector.