United Access Technologies LLC v. AT&T Inc. et al

Filing 105

MEMORANDUM OPINION re claim construction. Signed by Judge Leonard P. Stark on 11/4/16. Associated Cases: 1:11-cv-00338-LPS, 1:11-cv-00339-LPS, 1:11-cv-00341-LPS (ntl)

IN THE UNITED STATES DISTRICT COURT
FOR THE DISTRICT OF DELAWARE
UNITED ACCESS TECHNOLOGIES, LLC,
· Plaintiff,
C.A. No. 11-339-LPS

v.
CENTURYTEL BROADBAND SERVICES,
LLC and QWEST CORPORATION,
Defendants.
UNITED ACCESS.TECHNOLOGIES, LLC,
Plaintiff,

C.A. No. 11-338-LPS

v.
AT&T INC., et al.,
Defendants.
UNITED ACCESS TECHNOLOGIES, LLC,
. Plaintiff,

C.A. No. 11-341-LPS

v.
FRONTIER COMMUNICATIONS
CORPORATION,
Defendant.

Stamatios Stamoulis and Richard C. Weinblatt, STAMOULIS & WEINBLATT LLC,
Wilmington, DE
Steven Callahan, Martin Robson, Anthony M. Garza, and C. Luke Nelson, CHARRON
CALLAHAN ROBSON & GARZA, Dallas, TX
Attorneys for Plaintiff

Benjamin J. Schladweiler, ROSS ARONSTAM & MORITZ LLP, Wilmington, DE
Bryant C. Boren, Jr., Jon V. Swenson, J_ason German, Betsy Boggs, Jay B. Schiller, BAKER
, BOTTS LLP, Palo Alto, CA
Attorneys for Defendants AT&T Corp., AT&T Services, Inc., and SBC Internet Services,
LLC
Phillip A. Rovner and Jonathan A. Choa, POTTER ANDERSON & CORROON, LLP,
Wilmington, DE
David M. Maiorana, JONES DAY, Cleveland, OH
Olivia E. Marbutt, JONES DAY, Atlanta, GA
Attorneys for Defendant Frontier Communications Corporation.
Richard L. Renck, DUANE MORRIS LLP, Wilmington, DE
Alison H. Hutton, DUANE MORRIS LLP, Atlanta, GA
Attorneys for Defendant CenturyTel Broadband Services, LLC and Qwest Corporation

MEMORANDUM OPINION

f~P.k

November 4, 2016
Wilmington, Delaware
STARK, U.S. District Judge:

On April 15, 2011, Plaintiff United Access Technologies LLC ("Plaintiff') filed suit
against Defendants AT&T Inc., et. al., CenturyTel Broadband Services, LLC, et. al., and Frontier
Communications Corporation. alleging infringement of U.S. Patent Nos. 5,844,596 ("the '596
patent"), 6,243,446 ("the '446 patent") and 6,542,585 ("the '585 patent") (together, "the patentsin-suit"). The patents-in-suit are directed to systems for transmitting data to residences or
businesses over existing telephone wiring without interfering with telephone signals or the
switching equipment that is part of the public switched telephone network ("PTSN"). All share
the same specification.
The parties submitted technology tutorials and claim construction briefs. (D.I. 151, 154,
162, 166) 1 Defendants moved to strike several of Plaintiffs claim constructions (D.I. 152), and
the parties submitted briefing on that motion (D.I. 153, 156, 157, 158). The Court held a claim
construction hearing on September 6, 2016. (See D.I. 171 ("Tr."))

I.

LEGAL STANDARDS
The ultimate question of the proper construction of a patent is a question oflaw. See Teva

Pharm. USA, Inc. v. Sandoz, Inc., 135 S. Ct. 831, 837 (2015) (citing Markman v. Westview
Instruments, Inc., 517 U.S. 370, 388-91 (1996)). "It is a bedrock principle of patent law that the
claims of a patent define the invention to which the patentee is entitled the right to exclude."

Phillips v. AWH Corp., 415 F.3d 1303, 1312 (Fed. Cir. 2005) (internal quotation marks omitted).

1

The references to the docket are to United Access Technologies LLC v. CenturyTel
Broadband Services LLC, C.A. No. 11-339-LPS.
1

"[T]here is no magic formula or catechism for conducting claim construction." Id. at 1324.
Instead, the court is free to attach the appropriate weight to appropriate sources "in light of the
statutes and policies that inform patent law." Id.
"[T]he words of a claim are generally given their ordinary and customary meaning ...
[which is] the meaning that the term would have to a person of ordinary skill in the art in
question at the time of the invention, i.e., as of the effective filing date of the patent application."
Id. at 1312-13 (internal citations and quotation marks omitted). "[T]he ordinary meaning of a

claim term is its meaning to the ordinary artisan after reading the entire patent." Id. at 1321
(internal quotation marks omitted). The patent specification "is always highly relevant to the
claim construction analysis. Usually, it is dispositive; it is the single best guide to the meaning of
a disputed term." Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed. Cir. 1996).
While "the claims themselves provide substantial guidance as to the meaning of particular
claim terms," the context of the surrounding words of the claim also must be considered.
Phillips, 415 F.3d at 1314. Furthermore, "[o]ther claims of the patent in question, both asserted

and unasserted, can also be valuable sources of enlightenment ... [b ]ecause claim terms are
normally used consistently throughout the patent .... " Id. (internal citation omitted).
It is likewise true that"[ d]ifferences among claims can also be a useful guide .... For

example, the presence of a dependent claim that adds a particular limitation gives rise to a
presumption that the limitation in question is not present in the independent claim." Id. at 131415 (internal citation omitted). This "presumption is especially strong when the limitation in
dispute is the only meaningful difference between an independent and dep~ndent claim, and one
party is urging that the limitation in the dependent cl~im should be read into the independent
2

claim." SunRace Roots Enter. Co., Ltd. v. SRAM Corp., 336 F.3d 1298, 1303 (Fed. Cir. 2003).
It is also possible that "the specification may reveal a special definition given to a claim
term by the patentee that differs from the meaning it would otherwise possess. In such cases, the
inventor's lexicography governs." Phillips, 415 F.3d at 1316. It bears emphasis that "[e]ven
when the specification describes only a single embodiment, the claims of the patent will not be
read restrictively unless the patentee has demonstrated a clear intention to limit the claim scope
using words or expressions of manifest exclusion or restriction." Hill-Rom Servs., Inc. v. Stryker

Corp., 755 F.3d 1367, 1372 (Fed. Cir. 2014) (quoting Liebel-Flarsheim Co. v. Medrad, Inc., 358
F.3d 898, 906 (Fed. Cir. 2004)) (internal quotation marks omitted).
In addition to the specification, a court "should also consider the patent's prosecution
history, if it is in evidence." Markman v. Westview Instruments, Inc., 52 F.3d 967, 980 (Fed. Cir.
1995), aff'd, 517 U.S. 370 (1996). The prosecution history, which is "intrinsic evidence,"
"consists of the complete record of the proceedings before the PTO [Patent and Trademark
Office] and includes the prior art cited during the examination of the patent." Phillips, 415 F.3d
at 1317. "[T]he prosecution history can often inform the meaning of the claim language by
demonstrating how the inventor understood the invention and whether the inventor limited the
invention in the course of prosecution, making the claim scope narrower than it would otherwise
be." Id.
In some cases, "the district court will need to look beyond the patent's intrinsic evidence
and to consult extrinsic evidence in order to understand, for example, the background science or
the meaning of a term in the relevant art during the relevant time period." Teva, 135 S. Ct. at
841. Extrinsic evidence "consists of all evidence external to the patent and prosecution history,

3

including expert and inventor testimony, dictionaries, and learned treatises." Markman, 52 F.3d
at 980. For instance, technical dictionaries can assist the court in determining the meaning of a
term to those of skill in the relevant art because such dictionaries "endeavor to collect the
accepted meanings of terms used in various fields of science and technology." Phillips, 415 F.3d
at 1318. In addition, expert testimony can be useful "to ensure that the court's understanding of·
the technical aspects of the patent is consistent with that of a person of skill in the art, or to
establish that a particular term in the patent or the prior art has a particular meaning in the
.pertinent field~" Id. Nonetheless, courts must not lose sight of the fact that "expert reports and
testimony [are] generated at the time of and for the purpose of litigation and thus can suffer from
bias that is not present in intrinsic evidence." Id. Overall, while extrinsic evidence "may be
useful" to the court, it is "less reliable" than intrinsic evidence, and its consideration "is unlikely
to result in a reliable interpretation of patent claim scope unless considered in the context of the
intrinsic evidence." Id. at 1318-19. Where the intrinsic record unambiguously describes the
scope of the patented invention, reliance on any extrinsic evidence is improper. See Pitney

Bowes, Inc. v. Hewlett-Packard Co., 182 F.3d 1298, 1308 (Fed. Cir. 1999) (citing Vitronics, 90
F.3d at 1583).
Finally, "[t]he construction that stays true to the claim language and most naturally aligns
with the patent's description of the invention will be, in the end, the correct construction."

Renishaw PLC v. Marposs Societa 'per Azioni, 158 F.3d 1243, 1250 (Fed. Cir. 1998). It follows
that "a claim interpretation that would exclude the inventor's device is rarely the correct
interpretation." Osram GmbHv. Int'! Trade Comm'n, 505F.3d1351, 1358 (Fed. Cir. 2007)
(quoting Modine Mfg. Co. v. US. Int'! Trade Comm 'n, 75 F.3d 1545, 1550 (Fed. Cir. 1996)).

4

II.

MOTION TO STRIKE
Defendants have moved to strike (D.I. 152) Plaintiffs proposed constructions for "signal

interface," "telephone exchange," and "telephone voice band," as well as Plaintiffs position that
the preambles of the asserted claims are not limiting. Defendants' arguments are based on the
claim construction decision in United Access v. EarthLink, Inc., No. 02-cv-272-MPT (D. Del.),
an earlier case in which Plaintiffs predecessor-in-interest asserted the patents-in-suit. There,
Magistrate Judge Mary Pat Thynge construed several of the same claim terms that are at issue in
this case. (See id. at D.I. 614; see also Inline Connection Corp. v. AOL Time Warner Inc., 302 F.
Supp. 2d 307, 320-34 (D. Del. 2004)) Defendants argue that collateral estoppel bars Plaintiff
from re-litigating those constructions because: they formed the basis of Judge Thynge's decision
to grant partial summary judgment; Plaintiffs predecessor appealed several of the claim
constructions and the partial summary judgment decision; and the Federal Circuit summarily
affirmed the Court's rulings. (DJ. 153 at 1-3; D.I. 154 at 7) Defendants raised these arguments
in their claim construction brief, and in a separate Motion to Strike. Plaintiff responded to the
arguments in its own claim construction briefing and in separate briefing on the Motion to Strike.
In order to fully consider Defendants' Motion and other arguments relating to estoppel,

the Court found it necessary to review in their entirety all of Plaintiffs arguments regarding the
disputed terms. After doing so, the Court determined that none of these arguments provided a
persuasive reason for the Court to depart from Judge Thynge's claim constructions. Therefore,
Defendants' Motion to Strike (D.I. 152) will be DENIED as moot.

5

III.

CONSTRUCTION OF DISPUTED TERMS

A. .

"signal interface" and "public trunk line" 2

Plaintiff
signal interface: a device interposed at a point of convergence that is downstream from the
telephone exchange and performs the recited functions of the incorporated circuitry

public trunk line: the term "public trunk line" does not appear in any claim terms. As a result, ·
United Access contends that the Court should not construe the terms
Defendants
signal interface: a device interposed on the opposite end (i.e., the local side) of the public trunk
line (as defined by the inventor in the patent) from the telephone exchange that performs the
recited functions of the incorporated circuitry and prevents all non-telephone signals from
traveling upstream from the signal interface to the telephone exchange

public trunk line: the inventor defined public trunk line in the patent as: "the telephone lines
comprising the public telephone network"
Court
signal interface: a device interposed on the opposite end (i.e., the local side) of the public
trunk line (i.e., the telephone lines comprising the public telephone network) from the
telephone exchange that performs the recited functions of the incorporated circuitry

The parties have two disputes regarding these terms. First, they disagree about whether a
signal interface is necessarily located at the boundary of the telephone network and the private,
local network. Second, they disagree about whether the signal interface necessarily prevents all
non-telephone signals from traveling upstream from the signal interface to the telephone
exchange.
Initially, the parties disagree about whether the term "signal interface" has a plain and
ordinary meaning to a person of skill in the art. (D .I. 162 at 12) Citing a computing dictionary,

2

The term "signal interface" term appears in claim 61 of the '596 patent; claims 1-3 of the
'446 patent; and claims 1, 2, 4, and 8 of the '585 patent. The term "public trunk line" appears in .
Defendants' construction of "signal interface."
6

Plaintiff argues that the plain and ordinary meaning of "interface" is a "common boundary and
links between two systems, devices or programs" or "[t]he signal connection and associated
control circuits that are used to connect devices." (D .I. 151 at 17) Because neither definition
specifies that an interface must be placed at a particular location, Plaintiff argues, imposing such
a requirement via claim construction would improperly import limitations from the specification
into the claims. (Id. at 15) Defendants disagree, arguing that the term "signal interface" does not
have a plain and ordinary meaning to one of skill in the art, and that such a person would
therefore tum to the specification to discern its meaning. (D.I. 162 at 12-13) The Court agrees
with Defendants. Plaintiff has not described who it believes a person of ordinary skill in the art
is, nor provided a persuasive argument that, for such a person, Plaintiffs computing dictionary
definition of "interface" reflects the plain and ordinary meaning of the term "signal interface."
Turning to the specification, Defendants contend that it makes clear that the term "signal
interface" refers to a device located at the interface of the public telephone network and a local
network, and not merely "downstream" from a telephone exchange. 3 The specification describes
the invention as a whole as a means of transmitting signals between networks of telephone wiring
and a high capacity communication line, with the transmission occurring "at a common point of
access" to the high capacity line where the networks of telephone wiring "converge." See '596
pat. col. 1:23-28. The patent states th~t the invention includes a device located at this point of
convergence. Id. at 1:62-2:6; see also 3:48-55, 4:53-55, 8:9-18, 8:62-9:6. It is undisputed that
the specification does not teach the use of a signal interface at another location on the public

3

This is consistent with the EarthLink Court's construction. See Inline Connection Corp.,
302 F. Supp. 2d at 321-324.
7

telephone network. (D.I. 154 at 11-12) Defendants argue that a person of ordinary skill in the art
at the time of the invention would infer from this

cont~xt

that the "signal interface" of the claims

must be located at the boundary of the public and local networks.
Plaintiff counters that the claims themselves make clear that the concept of a signal
interface does not inherently include such a "positional" limitation because the asserted claims
themselves include positional limitations. In Plaintiffs view, these other limitations, rather than
the term "signal interface" itself, specify what, if any, positional requirements the patentee
intended to impose upon the claimed signal interfaces.
Claim language must be construed in the context of the claim as a whole. !GT v. Bally

Gaming Int'!, Inc., 659 F.3d 1109, 1117 (Fed. Cir. 2011). "Extracting a single word from a
claim divorced from the surrounding limitations can lead construction astray." Id. Considering
each of the asserted claims as a whole, the Court concludes that each includes a limitation that
the signal interface be located at the far end of the public trunk line, at the point where the line
connects to the local telephone network. See, e.g., '596 pat. col. 76:24-26 (requiring "a signal
interface coupled between the external source of information and the telephone wiring
network"); '446 pat. col. 70:21-22 (same); '585 pat. col. 70:13-24 (describing use of"signal
interface" designed to "receiv[e] ... external signals" and to "transmit [those signals] ... over
the telephone wiring network"). Thus, even if Plaintiff is correct that a person of ordinary skill
would understand that a signal interface is not inherently required to be located at the
intersection of the public telephone lines and the lines that run separately to particular structures,
the Court concludes that a person of ordinary skill in the art would understand that to be a

8

limitation imposed by the claims themselves. 4 Thus, the Court construes the term signal
interface and its accompanying positional limitations as requiring at least that the signal interface
be interposed on the local end of the public trunk line.
Having resolved the positioning issue, the Court next considers whether a signal interface
necessarily performs the function of preventing all non-telephone signals from traveling
upstream from the signal interface to the telephone exchange. Defendants note that the
specification of the patents-in-suit at times imputes this function to the signal interface. (D .I. 154
at 12-13) Further, Defendants suggest that the patentee's desire to impose a requirement that the
signal interface prevent up-stream transmissions is evident from its citation of United States
regulations that prohibit the transmission of high-frequency signals over telephone wires. (Id.)
Plaintiff counters that some of the claims of the patents explicitly require the signal interface to
prevent such upstream transmissions, suggesting that this capability is not an inherent feature of
the signal interface itself. See, e.g. '596 pat. col. 69:41-44 (requiring signal interface include
"circuitry for ... preventing transmission of [non-telephone] signal to the telephone exchange").
The Court agrees with Plaintiff. Although Defendants cite prosecution history in favor of
their interpretation, that history refers specifically to those claims that contain an explicit
requirement that the signal interface block upstream data transmission, and therefore does not
support their position that such blocking is an inherent property of "signal interface" claims
without such an explicit limitation. (See D.I. 166 at 10; D.I. 154-9 at 24) While the prosecution
history indicates that the claims that do not include an upstream transmission limitation (i.e.,

4

Plaintiff contends that adopting such a construction would read out a preferred
embodiment, i.e., Figure lb of the '596 patent. Having reviewed the intrinsic evidence, the Court
is persuaded by Defendants' interpretation of that figure. (D.I. 162 at 13-14)
9

'596 pat. cl. 61) include circuitry for preventing transmission of signals in the high-frequency
band onto parts of the telephone wiring network, the patentee stated only that the embodiments
of those claims could block signals to "telephone devices:" (D.I. 154-9 at 29) In the context of
the asserted patents, the term "telephone device" refers to devices employed by end users, and
does not include within its scope the telephone exchange. See, e.g. '596 pat. col. 76:11-16
(claiming "system for communicating information ... over a telephone wiring network used for
passing telephone signals in a telephone voice band between a plurality of telephone devices and
a telephone exchange"). Thus, while Defendants are correct that the specification makes clear
why blocking upstream transmission would be an advantageous feature for a signal interface
(because it would ensure that the claimed system satisfied then-pertinent legal requirements), that
is an insufficient justification for reading a limitation from the specification into the claim. As
such, the Court has not adopted this portion of the Defendants' proposed construction of "signal
interface."
Given the reasoning above, there is no need to separately construe "public trunk line."

B.

''telephone exchange" 5

Plaintiff
telephone switching equipment including equipment within a central office or including.a
private branch exchange
Defendants
a switching center- for connecting and switching phone lines

Court
a switching center for connecting and switching phone lines

5

This term appears in claim 61 of the '596 patent; claim 1 of the '446 patent; and claim 1
of the '585 patent.
10

· Defendants argue that the term "telephone exchange" refers to a central office that
contains equipment for connecting and switching telephone lines. (D .I. 162 at 7) Plaintiff
contends that the term "telephone exchange" refers only to the equipment for connecting and
switching, such that the claims can encompass both an exchange located at a central office and a
"private branch exchange" located on a subscriber's premises. (See D.I. 166 at 5)
The intrinsic evidence makes clear that "telephone exchange" and "private branch
exchange" have distinct meanings. 6 The specification explains that public telephone wires run

from the "public" or "local" telephone exchange to the "access points" to which users connect.
See '596 pat. at 9:1-8 (describing "local.telephone exchange" as.source of telephone wire pairs
that form "the trunk line"); see also id. at 1:23-44. In some cases - for example; in the case of a
wire running from an individual residence to a telephone pole - users connect to the access point
directly. Id. In other cases, such as where there are multiple end users at a single location who
wish to communicate both among themselves as well as with individuals located at external
locations, individual lines first connect to a "private branch exchange," which both routes cans
within the location and connects to the public network. Id. Essentially, the private branch
exchange allows users at the same location to communicate with each other without having to
access the public telephone network. As the patent explains:

6
. Wjth

respect to this claim, the parties submitted competing expert declarations, which
the parties then discussed at the claim construction hearing. (Tr. at 86-88, 92) Because the
meaning of the term as used in the asserted patents is clear from the intrinsic evidence, however,
the Court did not rely on the extrinsic evidence in evaluating the meaning of this term~ See
Phillips, 415 F.3d at 1317 (finding that, "while extrinsic evidence can shed useful light on the
relevant art ... it is less significant than the intrinsic record in determining the legally operative
meaning of claim language" and describing decision to admit extrinsic evidence as matter of
"sound discretion" of district court).
11

Commercial buildings ... include locations where many telephone
lines converge. Often, the individual wires leading to the various
rooms of the building converge at what is called a "PBX," or private
branch exchange.
Such an exchange is provided because
considerable communication between rooms is required that is not,
of course, economically provided by the public telephone exchange.
'596 pat. col. 6:46-52.
In arguing that the term "telephone exchange" refers to the "local exchange," Defendants

seek to limit the invention to embodiments in which the claimed system facilitates
communications via a public exchange. Plaintiff argues that limiting the claims in this way
would be improper because it would read out preferred embodiments that employ private branch
exchanges, such as the embodiment outlined in Figure 1b of the patents' specifications. The
. Court disagrees with Plaintiff. The requirement that the claimed system facilitate connections
with a local exchange does not preclude the possibility that the system does so in conjunction
with a public branch exchange. See '596 pat. fig. 1b (showing "local exchange 475" connecting
to "PBX 500" which in tum connects to "transceiver/switch 400" [the signal interface]).
Conversely, the patent does not disclose an embodiment having only a public branch exchange
but no connection to the local exchange.
The fact that the patent does not disclose an embodiment having no connection to a local
exchange is not dispositive of the scope of the claims. See Hill-Rom Servs., Inc., 755 F.3d at
1372. But the Plaintiff does not provide a persuasive explanation for why a person of ordinary
skill in the art would have read the patent as claiming such an embodiment. Thus, the Court is
left with the strong intrinsic evidence that the patentee used the term "telephone exchange" to
refer to a "local exchange." In contrast, the "public branch exchange" is consistently described
as an "access point." The Court finds that a person of ordinary skill in the art would understand

12

I
I

that the patentee used "telephone exchange" to refer to a local bxchange (and the equipment
I

therein) but not a public branch exchange.

13

C.

· "high frequency band of frequencies above the highest frequency of the
telephone voice band;" "high frequency band," "high band of frequencies" 7

Plaintiff
frequencies above the telephone voice band between 0.25 MHZ and an undetermined upper
limit
· (alternate construction: "frequencies above the telephone voice band")
Defendants
Indefinite.
If not indefinite: including frequencies at or above 24 MHZ and excluding frequencies at or
below 18 MHZ
Court·
frequencies above the te~ephone voice band between 0.25 MHZ and an undetermined upper
limit
The disputed terms appear together in the patents, such that "high frequency band above
the voice band" provides antecedent basis for "high frequency band."
The specifications of the patents explain the technical significance and function of the
high-frequency band. When separate signals are sent over a single wire, each signal is assigned
to a discrete range offrequencies. These ranges of frequencies, called "bands" or "channels,"
make it possible to differentiate among the different signals sent over the wire. '596 pat. col.
18:30-42; see also id. at 55:51-57. Therefore, the Court finds that the term "band" refers· to "a
range of frequencies."
The parties do not dispute that the patent uses the term "voice band" to refer to the
particular range of frequencies customarily used to carry telephone signals. The claim term
-requires the "high frequency band" of signals to be above the "voice band." Consequently, the

7

These terms appear in claim 61 of the '5 96 patent; c,laims 1 and 3 of the '446 patent; and
claims 1 and 4 of the '585 patent.
14

bottom end of the range of frequencies comprising the "high frequency band" must be higher
than the top end of the "voice band." See id. at 53:59-64, 55:13-17, 51:51-57, 56-27-30.
Defendants contend, and Plaintiffs do not contest, that "high-frequency" has no plain and
ordinary meaning in the art. The specification provides considerable guidance regarding the
meaning of "high frequency" in the context of the asserted patents. It explains that, for various
technical reasons, it is desirable to minimize the frequency of the highest-frequency signal by
placing it as close to the voice band as possible, without causing interference. Id. at 19:14-25.
This suggests that the patentee used the term "high frequency" to highlight that the selected band
must, at the very least, avoid interference with the voice band.
The specification also provides guidance as to the minimum frequency that could be
considered a "high" frequency. The specification describes a particular group of preferred
embodiments as placing the high-frequency band "just above the voice band." Id. at 24:48-54.
The specification lists specific examples of these embodiments. Of these, the minimum
frequency at which the high-frequency signal is transmitted is 0.25 MHZ. From this, the Court
understands that 0.25 MHZ is the lowest possible "high frequency" transmission (i.e.
transmission that will not interfere with the voice band signal).
Defendants nevertheless argue that the claims are indefinite, citing various portions of the
specification that describe certain frequencies as "low" or "high," and noting that some of the
disclosed "low" frequencies are higher than the "high" frequencies (and vice versa). But as
Plaintiffs answering brief explains at length, each such reference uses the terms "low" and
"high" in a relative sense, characterizing a frequency as "low" or "high" in the context of the
preferred embodiment being described, in the context of the technology at issue, or in

15

comparison to other preferred embodiments. (See D .I. 166 at 16-18) Accordingly, the Court
finds that a person of ordinary skill in the art would understand that these examples of "low" and
"high" are not meant to impose numerical limitations on the claims, but rather to distinguish and
explain different preferred embodiments and describe the underlying science. As such,
Defendants have not demonstrated by clear and convincing evidence that these references to
"high" and "low" frequencies render the meaning of the "high frequency" claim terms uncertain
to a person or ordinary skill in the art. See Microsoft C01p. v. i4i Ltd. Partnership, 564 S.Ct.
2238, 2242 (2011).
Defendants' citations to prosecution history are similarly unpersuasive. Defendants point
to a portion of the prior art in which the patentee distinguished its invention over two prior art
references, Reichert and Camarata, which both describe filtering signals. The Reichert prior art
discloses a filter that separates voice and data signals by preventing high-frequency signals from
passing onto wiring, which filters signals of over 0.004 MHZ. The Camarata prior art filters
signals of greater than 0.5 MHZ. The patentee distinguished its invention from these references
by explaining that
independent claim 61 recites a branch network of the telephone
wiring network which includes circuitry for preventing transmission
of signals in the high frequency band to a telephone device on a
branch network. Neither Camarata nor Reichert disclose a wiring
network with any sort of branches, nor any type of circuitry for
preventing transmission of signals in the high frequency band onto
portions of the wiring network.
(D.I. 154-9 at 29) Defendants argue that the patentee intended by these statements to highlight
two, separate differences between its invention and the prior art: a distinction based on
branching, and a distinction based on the presence of a low-pass filter.

16

While this would appear on its face to be a reasonable way to read the patentee's
statement, a closer inspection of the references being discussed renders that interpretation
· implausible. Because the Reichert filter allows only the voice band to pass onto the wiring
network (see the Court's construction of"telephone voice band," below), the patentee could not
have credibly have argued that its invention was distinct from Reichert on the basis that Reichert
did not include any circuitry for preventing transmission of signals in a high frequency band
"above the voice band." As such, the patentee's statements are best understood as distinguishing
the claimed invention from the prior art on the basis that the invention has both circuitry for
filtering high frequency signals and a branch network. For this reason, the Court is not
persuaded that the patentee's statements implicitly disclaim any particular groups of frequencies
from the scope of the term "high frequency."
For the foregoing reasons, the Court adopts Plaintiff's proposed construction.

D.

"telephone voice band" 8

Plaintiff
this term does not need further construction and the Court should not impose numerical limits
on this term
Defendants
band of frequencies of 0-4 kHz

Court
band of frequencies of 0-4 kHz
The parties agree that a person of ordinary skill in the art would understand that the "voice
band" refers to the frequencies used for ordinary telephone service. (See D.I.154 at 29; D.L 151

8

This term appears in claim 61 of the '596 patent; claim 1 of the '446 patent; and claim 1
of the '585 patent.
17

at 23) This understanding of the term is consistent with the intrinsic record. See, e;g., '596 pat.
col. 4 7 :3 5-48. The parties further agree that it excludes frequencies sent at above 5 kHz, as the
specification notes. Id. at 21 :34-39.
The parties disagree about the precise range of the voiceband. Plaintiff argues that the
Court should not "set numerical limitations" on the voice band, noting that various sources of
evidence define the "voice band" differently. (D.I. 151 at 23-24) But the Court finds persuasive
Defendants' expert report, which explains that one of ordinary skill in the art at the time of the
invention would have understood that "telephone voice band" refers to the range 0-4 kHz
because, at the time the voice frequency range was known to be 0.3-3.4 kHz and it was known to
be desirable to include a guard band around those frequencies. (See D.l. 162 at 21) This
explanation reconciles the differences among the various intrinsic and extrinsic evidence Plaintiff
cites in its brief (see D.l. 151 at 22-24) and is consistent with the construction to which the
parties agreed in the EarthLink litigation. (See D.I. 154 at 28) Therefore, the Court adopts
Defendants' proposed construction.

E.
I

"external source of information" 9 and "external signals" 10

Plaintiff
No construction necessary

9

This. term appears in claim 61 of the '596 patent; claim 1 of the '446 patent; and claims 1
and 8 of the '585 patent.
10

This term appears in claim 61 of the '596 patent; claims 1 and 4 of the '446 patent; and
claims 1 and 2 of the '585 patent.
18

Defendants
external source of information: a communication line separate from the communication lines
that 'carry telephone signals between telephone devices and the telephone exchange (i.e.,
physically separate from the public trunk line)
external signals: signals from the external source

Court
external source of information: the provider of the non-telephone signals
external signals: non-telephone signals sent to the signal interface
The parties disagree about whether the signals from an "external source" must be
transmitted to the claimed systems via a communication line that is physically separate from the
line that carries telephone signals between telephone devices and the telephone exchange.
Defendants argue that the external signals must be transmitted via a separate medium. They note
that the specification discloses real-world en:lbodiments that use a separate communication line,
and that the descriptions of many embodiments state that external signals are not intended to
communicate with the local telephone exchange. (D .I. 154 at 25)
Although the specification of the asserted patents· discloses embodiments of the claimed
invention with respect to which it would be technically impossible (or legally impermissible) to
implement the claimed system such that the external signals are transmitted via the public
telephone wires (i.e., the public trunk line), the Court is not persuaded that the patentee used the
term "external source of information" to rule out that possibility. Rather, the patent appears to
require nothing more than that the external signals be non-telephone signals, originating from a
source other than the public telephone system. The Court has construed the term accordingly.

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F.

"telephone wiring network" 11

Plaintiff
this term does not need further construction
Defendants
a network of twisted pair wiring
Court
a network of twisted pair wiring
The parties disagree about whether the telephone wiring network of the claims must be
comprised of "twisted pair" wires. Plaintiff argues that the patentee understood that telephone
signals may, but need not, be transmitted via twisted pair wiring. (D.I. 151 at 21-22) However,
as Defendants point out, the patentee used the words "twisted pair" and "telephone wiring"
synonymously throughout the specification, and consistently used different terms to identify
other types of cables. (See D.I. 162 at 21-22 (citing intrinsic evidence)) Further, the
specification explains that the patentee intended for the invention to be implemented over
existing twisted pair copper wires. (Id.) Thus, a person of ordinary skill in the art would
understand that the "telephone wiring network" of the claims refers to "twisted pair" wiring
networks.

G.

"signal interface including ... circuitry for limiting transmission of the
[internal signal I signals] in the high frequency band from the telephone
wiring network to the telephone exchange" 12

11

This term appears in claim 61 of the '596 patent; claims 1-3 of the '446 patent; and
claim 1 of the '585 patent.
12

These terms appear in claim 1 of the '446 patent and claim 1 of the '585 patent.

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Plaintiff
This term does not need further construction other than Court's construction (if any) of "signal
interface," "high frequency band," "telephone wiring network," and "telephone exchange"
Defendants
the signal interface includes circuitry that prevents high frequency signals (as construed) from
traveling upstream from the signal interface to the telephone exchange
Court
the signal interface includes circuitry that prevents high frequency signals (as construed) from
traveling upstream from the signal interface to the telephone exchange
Plaintiff contends that no construction of this term is necessary, beyond the Court's
construction of the other disputed claim terms it encompasses. However, because the Court's
constructions of the terms "signal interface," "high frequency band," "telephone wiring
network," and "telephone exchange" are consistent with Defendants' proposed constructions, the
Court has adopted Defendants' proposed construction of this term as well.

H.

"a telephone wiring network used for passing telephone signals in a
telephone voice band between a plurality of telephone devices and a
telephone exchange" 13

Plaintiff
This term, which appears in the preambles of the asserted patents, is not limiting. It does not
. need further construction other than the Court's construction (if any) of"telephone wiring
network," "telephone voice band," and "telephone exchange."
Defendants
The preamble of each asserted claim is a substantive limitation which must be considered in
the infringement analysis.
Accordingly, "the telephone wiring network (as defined above) is used for passing telephone
signals in the telephone voice band (as defined above) to the telephone exchange"

13

This term appears in claim 61 of the '596 patent; claims 1-3 of the '446 patent; and
claim 1 of the '5 85 patent.
21

Court
The preamble of each asserted claim is a substantive limitation which must be considered in
the infringement analysis.

Accordingly, "the telephone wiring network (as defined above) is used for passing telephone
signals in the telephone voice band (as defined above) to the telephone exchange"
Defendants ask the Court to find that portions of the claims' preambles are limiting on the
claims. The Court agrees that these portions of the claims are limiting, as they provide
antecedent basis for the term "telephone wiring network" cited in the claims, ahd give "life,
meaning, and vitality" to the claims by explaining what the telephone wiring network is (i.e., a
network "used for passing telephone signals in a telephone voice band between a plurality of
telephone devices and a telephone exchange"). Catalina Mktg. Int'!, Inc. v. Coo/savings.com,
Inc., 289 F.3d 801, 808 (Fed. Cir. 2002). Therefore, the Court adopts Defendants' proposed
construction.

III.

CONCLUSION
The Court construes the disputed terms as explained above. An appropriate Order

follows.

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