Centre One v. Cox Communications Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Centre One (Nevada)
  • Defendant: Cox Communications, Inc. (Delaware)
  • Plaintiff’s Counsel: Umberg Zipser LLP; Friedman, Suder & Cooke
• Case Identification: 8:19-cv-01832, C.D. Cal., 09/25/2019
• Venue Allegations: Plaintiff alleges venue is proper because Defendant maintains multiple regular and established places of business within the Central District of California, offers the accused products for sale within the district, and has purposefully transacted business there since 1997.
• Core Dispute: Plaintiff alleges that Defendant’s VoIP (Voice over Internet Protocol) telephony services and the underlying network infrastructure infringe six patents related to systems and methods for interfacing traditional public switched telephone networks (PSTN) with modern IP-based networks.
• Technical Context: The technology at issue concerns the foundational architecture for bridging legacy circuit-switched telephone systems with packet-switched VoIP networks, enabling advanced and unified communication features.
• Key Procedural History: The complaint notes that two of the asserted patents, U.S. Patent Nos. 7,068,668 and 7,486,667, were previously asserted in litigation against other parties in 2009. During that prior case, both patents underwent inter partes reexamination proceedings at the U.S. Patent and Trademark Office and were subsequently "confirmed as patentable," which may be presented by the Plaintiff to suggest the patents' resilience to validity challenges.

Case Timeline

Date	Event
1997-01-01	Cox begins offering circuit-switched telephony services
2000-01-07	Earliest Priority Date for all Asserted Patents
2005-03-01	Approx. date Cox begins modifying network for VoIP ("mid-2000s")
2006-06-27	U.S. Patent No. 7,068,668 Issue Date
2009-02-03	U.S. Patent No. 7,486,667 Issue Date
2009-01-01	Prior litigation involving ’668 and ’667 patents filed
2012-02-28	U.S. Patent No. 8,125,982 Issue Date
2013-06-12	Reexamination Certificate issued for '668 Patent
2013-09-16	Reexamination Certificate issued for '667 Patent
2014-05-13	U.S. Patent No. 8,724,643 Issue Date
2017-09-26	U.S. Patent No. 9,774,745 Issue Date
2018-08-28	U.S. Patent No. 10,063,710 Issue Date
2019-09-25	Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 7,068,668 - Method and Apparatus for Interfacing a Public Switched Telephone Network and an Internet Protocol Network for Multi-Media Communication

The Invention Explained

• Problem Addressed: The patent addresses the technical challenge of integrating traditional, circuit-switched Public Switched Telephone Networks (PSTN) with packet-switched Internet Protocol (IP) networks to enable real-time voice communication, a task for which the two incompatible network types were not originally designed (Compl. ¶23; ’668 Patent, col. 2:42-44).
• The Patented Solution: The invention proposes a central communication system that acts as an intelligent bridge between the two networks. The system uses a computer-controlled switch, a gateway for data conversion, and a gatekeeper for traffic management to route calls seamlessly between PSTN and IP devices ('668 Patent, Abstract; Fig. 2). A key feature is the ability to receive a single incoming call and simultaneously route it to multiple pre-programmed destination devices, which can be on the PSTN, the IP network, or both, providing a "follow-me" service ('668 Patent, col. 7:11-24).
• Technical Importance: This architecture enabled the creation of unified communication services that merged the reliability of the PSTN with the flexibility and global reach of the internet, laying the groundwork for many modern telephony features (Compl. ¶¶12, 20).

Key Claims at a Glance

• The complaint asserts independent claim 3, which was amended during a prior reexamination proceeding (Compl. ¶57; '668 Patent Reexam Cert., col. 2:20-56).
• The essential elements of independent claim 3 include:
  • A system with a computer controlled switch to connect to the PSTN and route calls between the PSTN and IP networks.
  • Gate interface circuitry comprising a gateway (to interface voice circuits) and a gatekeeper (to manage address translation, bandwidth, etc.).
  • A voice response unit connected between the gateway and switch to convert voice signals into digital tones for the switch.
  • The switch stores destination addresses on both the PSTN and IP network for each subscriber.
  • The switch can simultaneously route an incoming call to a plurality of a subscriber's pre-designated addresses on either or both networks.
• The complaint reserves the right to assert additional claims (Compl. ¶57).

U.S. Patent No. 7,486,667 - Method and Apparatus for Interfacing a Public Switched Telephone Network and an Internet Protocol Network for Multi-Media Communication

The Invention Explained

• Problem Addressed: Like its parent, the ’667 Patent addresses the problem of bridging the PSTN and IP network domains to provide more sophisticated and unified communication options than were previously possible (Compl. ¶23; ’667 Patent, col. 1:21-44).
• The Patented Solution: This patent claims a method for routing calls and handling messages. The method involves receiving a call from the internet, routing it to a subscriber's pre-designated IP and PSTN addresses, and, if the call is unanswered, taking a message and delivering it in a format determined by the subscriber (e.g., voice, e-mail, or facsimile) ('667 Patent, col. 7:16-32; Compl. ¶62).
• Technical Importance: The claimed method provided a practical means for implementing "unified messaging," ensuring that users would not miss communications regardless of the originating network type or their own location, and could receive messages in their most convenient format (Compl. ¶12).

Key Claims at a Glance

• The complaint asserts claim 14, which was added during a prior reexamination proceeding that also cancelled original claims 1-13 (Compl. ¶¶60, 63; '667 Patent Reexam Cert., col. 2:5-12).
• The reexamination certificate states that claim 14 depends from original claims 4 or 6, which were cancelled. For context, the core steps of the method from original independent claim 1, from which claims 4 and 6 depended, included:
  • Assigning a subscriber a plurality of predesignated destination addresses, including an IP address and a PSTN phone number.
  • Receiving a real-time voice call for the subscriber from a device on the Internet.
  • Automatically routing the received call to each of the predesignated addresses.
  • Determining the call is not picked up and taking a message for later delivery in a specified format (voice, e-mail, etc.).
• The complaint reserves the right to assert additional claims (Compl. ¶63).

U.S. Patent No. 8,125,982 - Providing Real-Time Voice Communication Between Devices Connected to an Internet Protocol Network and Devices Connected to a Public Switched Telephone Network

• Technology Synopsis: The patent discloses systems and methods for real-time voice communication between IP and PSTN devices, with a specific focus on providing a caller identification function upon routing of a call. The system uses a computer-controlled switch that stores at least one destination address on each network for a subscriber and performs call control functions (Compl. ¶68).
• Asserted Claims: At least independent claim 1 (Compl. ¶69).
• Accused Features: The complaint accuses Cox's residential and business VoIP products (e.g., VoiceManager Essential, Enhanced, Premium, and Hosted Voice) and the underlying network infrastructure that provides caller ID and other call routing functions (Compl. ¶69).

U.S. Patent No. 8,724,643 - Providing Real-Time Voice Communication Between Devices Connected to an Internet Protocol Network and Devices Connected to a Public Switched Telephone Network

• Technology Synopsis: The patent covers systems and methods for enabling real-time voice communication between IP and PSTN networks. The claimed operation involves converting voice signals to packetized data (and vice-versa) and using hardware and software components to perform call control and route calls to one or more destination addresses stored for a subscriber (Compl. ¶74).
• Asserted Claims: At least claims 10 and 11 (Compl. ¶75).
• Accused Features: The complaint targets Cox's residential and business VoIP products that operate on its network, which allegedly performs the signal conversion, call control, and routing steps claimed in the patent (Compl. ¶75).

U.S. Patent No. 9,774,745 - Providing Real-Time Voice Communication Between Devices Connected to an Internet Protocol Network and Devices Connected to a Public Switched Telephone Network

• Technology Synopsis: The patent claims a system for packetizing voice information from a telephone using a local gateway device (at the customer premise). This packetized data is transmitted over an IP network to a computer-controlled switch, enabling communication with a PSTN without requiring a traditional private branch exchange (PBX) (Compl. ¶80).
• Asserted Claims: At least independent claim 1 (Compl. ¶81).
• Accused Features: The infringement allegations are directed at Cox's VoIP products and infrastructure, which allegedly utilize customer premise gateways (MTAs) to packetize voice for transmission over its network, thereby embodying the claimed system (Compl. ¶¶40-41, 81).

U.S. Patent No. 10,063,710 - Providing Real-Time Voice Communication Between Devices Connected to an Internet Protocol Network and Devices Connected to a Public Switched Telephone Network

• Technology Synopsis: This patent claims systems and methods where a gate interface circuitry receives a call from an IP network device and depacketizes the voice data. A voice response unit then converts this data to digital tones, which are used by a computer control to switch the call to one of a plurality of stored destination addresses for the subscriber (Compl. ¶86).
• Asserted Claims: At least independent claim 1 (Compl. ¶87).
• Accused Features: The complaint accuses Cox's VoIP products and network infrastructure, alleging they employ gate interfaces and perform signal conversions and computer-controlled switching that map onto the claimed system and method (Compl. ¶87).

III. The Accused Instrumentality

Product Identification

• The accused instrumentalities are Cox's VoIP telephony services, identified as the "Accused Residential Products" and "Accused Business Products" (Compl. ¶¶24, 25). These include specific offerings such as "Voice Premier" for residential customers and "Business VoiceManager," "IP Centrex," and SIP/PRI Trunking for business customers (Compl. ¶¶24, 25, 52).

Functionality and Market Context

• The complaint alleges these services operate over a hybrid network infrastructure that Cox began building in the mid-2000s to migrate its legacy circuit-switched telephone customers to a "complementary VoIP overlay" (Compl. ¶¶26, 28).
• The network is alleged to use a combination of components to bridge the PSTN and IP worlds, including Nortel CS2K switches, softswitches, and various media gateways and session border controllers from Nuera, Metaswitch, and Acme Packet (Compl. ¶¶29, 31, 34, 37, 38). At the customer premise, the system uses gateway devices like Multimedia Terminal Adapters (MTAs), often embedded in modems, to perform signal conversion (Compl. ¶30, 40-41).
• The complaint includes a 2005 diagram illustrating Cox's "Circuit Switch to VoIP Evolution Plan," which shows how components like the CS2K switch, Nuera BTX media gateway, and embedded MTAs are interconnected (Compl. ¶29, p. 9).
• A more recent 2019 diagram from an Avaya document is also provided, which depicts Cox's modern SIP Trunking service using Metaswitch gateways and Acme Packet Session Border Controllers to interface between enterprise clients, the internet, and the PSTN (Compl. ¶36, p. 13).
• Functionally, the services provide advanced features central to the infringement allegations, such as "Simultaneous Ring" (routing a call to multiple numbers on IP or PSTN networks) and "readable voicemail" (voicemail-to-email conversion) (Compl. ¶¶43, 44).

IV. Analysis of Infringement Allegations

'668 Patent Infringement Allegations

Claim Element (from Independent Claim 3)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A system for providing real-time voice communication... comprising: a computer controlled switch operable for use by subscribers and adapted for connection to a local public switched telephone network...	Cox's network infrastructure includes computer-controlled softswitches and CS2K switches that manage and route calls between its IP network and the PSTN.	¶¶29, 34	col. 6:26-30
gate interface circuitry... includ[ing] gateway circuitry for interfacing... and gatekeeper circuitry for performing address translation, admission control, bandwidth management and zone management...	Cox's network allegedly uses media gateways (Nuera, Metaswitch) and Session Border Controllers (Acme Packet) that perform the claimed interfacing, address translation, and call control functions.	¶¶31, 37, 38	col. 6:31-42
a voice response unit... for receiving voice signals and converting them to digital tones for the switch.	Cox uses customer-premise MTAs and network gateways with Digital Signal Processors (DSPs) to perform the necessary signal conversion of voice signals for transmission.	¶¶30, 32, 40	col. 8:43-48
said computer controlled switch... simultaneously routes the call to a plurality of pre-designated destination addresses on the IP network, on the PSTN, or on both...	Cox's "Simultaneous Ring" feature allows a subscriber to designate up to three additional phone numbers on the IP or PSTN network to which an incoming call is simultaneously routed.	¶44	col. 7:11-17

'667 Patent Infringement Allegations

Claim Element (context from original Ind. Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
assigning a plurality of predesignated destination addresses to a subscriber, the destination addresses including an Internet Protocol (IP) address... and a... PSTN phone number	Cox's "Simultaneous Ring" feature allows subscribers to add additional phone numbers for simultaneous call routing, which "may correspond to addresses on an IP network or PSTN."	¶44	col. 7:5-10
receiving a real-time voice communication call directed to the subscriber, the received call originating from a device connected to the Internet	The accused services are VoIP services that operate over Cox's IP backbone and are designed to receive calls originating from and traversing the internet.	¶¶26, 34	col. 7:18-20
determining that the call is not being picked up... and taking a message for the subscriber for later delivery... in the form of a voice message, an e-mail message or a facsimile message	The "Voice Premier" service includes a voicemail feature that stores messages as audio files and can deliver them as written transcripts or emails to a subscriber's inbox.	¶43	col. 7:20-24

Identified Points of Contention

• Architectural Mapping: A likely area of dispute will be whether Cox's distributed, modern network architecture—which employs softswitches, session border controllers, and customer-premise gateways—maps onto the more discrete functional blocks described in the patents (e.g., a single "computer controlled switch" or "gatekeeper"). The defense may argue a mismatch between the claimed architecture and the accused system's implementation.
• Functional Scope: The infringement theory for the '668 Patent may turn on whether the general-purpose digital signal processing (e.g., codec-based packetization) performed by Cox's MTAs and gateways constitutes the specific function of a "voice response unit" that "convert[s]... voice data to digital tones" as claimed.
• Claim Validity: A threshold legal battle is likely to arise over the '667 patent. The complaint asserts claim 14, but the provided reexamination certificate indicates that this claim depends from parent claims that were cancelled during the same proceeding. This raises a significant question about the validity and enforceability of claim 14.

V. Key Claim Terms for Construction

The Term: "computer controlled switch"

• Context and Importance: This term appears in the independent claims of multiple asserted patents and is foundational to the claimed system. Its construction will be critical because the complaint identifies multiple, distinct components in Cox's network (legacy CS2K switches, modern softswitches, session border controllers) that collectively perform switching functions (Compl. ¶¶29, 34, 38). Practitioners may focus on whether this term must refer to a single, unitary device or can cover a distributed system of components.
• Intrinsic Evidence for a Broader Interpretation: The specification describes the switch by its function, stating it "is capable of Class 5 switching of PSTN lines" and is "controlled by a computer control" ('668 Patent, col. 6:26-30). This functional language may support an interpretation that covers any system or combination of devices that performs these tasks.
• Intrinsic Evidence for a Narrower Interpretation: The patent figures depict a single, discrete block labeled "SWITCH 101" ('668 Patent, Fig. 2). This depiction, combined with the reference to "Class 5 switching," may be used to argue that the term should be limited to a traditional, unitary telecommunications switch, not a disaggregated set of modern network elements.

The Term: "voice response unit"

• Context and Importance: This element from the '668 patent is required to "convert... depacketized voice data to digital tones for use by the switch" ('668 Patent, col. 6:47-48). The infringement allegation appears to map this to the function of Digital Signal Processors (DSPs) in Cox's network gateways and customer MTAs (Compl. ¶¶30, 32). The dispute will likely center on the technical meaning of "digital tones."
• Intrinsic Evidence for a Broader Interpretation: The patent's overall goal is to interface two different network types. A party could argue that any signal processing step that converts voice data from a format used by the gateway into a format usable by the switch falls within the scope of this term, regardless of the specific technology (e.g., tones vs. packets).
• Intrinsic Evidence for a Narrower Interpretation: A party could argue that "digital tones" has a specific technical meaning in the art (such as DTMF tones) that is distinct from the PCM/codec-based digital voice data streams generated by modern DSPs. The claim language specifying the tones are "for use by the switch" may suggest a particular type of input signal is required, potentially limiting the term's scope.

VI. Other Allegations

Indirect Infringement

• The complaint alleges facts that may support a claim for induced infringement. It states that Cox provides instructions to its subscribers on how to set up and use the accused features, such as "Simultaneous Ring" and "readable voicemail," which allegedly causes them to perform the infringing steps (Compl. ¶¶43, 44).

Willful Infringement

• While the complaint does not contain an explicit count for willful infringement, the prayer for relief requests "enhanced damages as permitted by 35 U.S.C. § 284" and a finding that the case is "exceptional" under 35 U.S.C. § 285 (Compl., p. 25). The complaint does not allege pre-suit knowledge, so any such claim would likely depend on Defendant's conduct after the complaint was filed.

VII. Analyst’s Conclusion: Key Questions for the Case

The resolution of this dispute may turn on the court's determination of the following key questions:

• A threshold legal issue will be one of claim validity: Can asserted claim 14 of the '667 patent be held valid and enforceable, given that the patent’s reexamination history appears to show it as a dependent claim whose parent claims were cancelled?
• A core technical issue will be one of architectural mapping: Can the elements of Cox’s modern, distributed VoIP architecture—composed of softswitches, session border controllers, and customer-premise gateways—be mapped onto the more discretely-defined components of the patented system, such as the "computer controlled switch" and "gatekeeper"?
• A key evidentiary question will be one of functional equivalence: Does the digital signal processing performed in Cox's accused network constitute the specific function of "convert[ing]... voice data to digital tones" as required by the "voice response unit" limitation, or is there a fundamental mismatch in the technical operation?