United States Court of Appeals 

for the Federal Circuit ______________________ 

COX COMMUNICATIONS, INC., COXCOM, LLC, 

COX ARKANSAS TELCOM LLC, COX 

COMMUNICATIONS ARIZONA LLC, COX ARIZONA 

TELCOM LLC, COX CALIFORNIA TELCOM LLC, 

COX COMMUNICATIONS CALIFORNIA LLC, COX 

COLORADO TELCOM LLC, COX CONNECTICUT 

TELCOM LLC, COX DISTRICT OF COLUMBIA 

TELCOM LLC, COX FLORIDA TELCOM LP, COX 

COMMUNICATIONS GEORGIA LLC, COX 

GEORGIA TELCOM LLC, COX IOWA TELCOM LLC, 

COX IDAHO TELCOM LLC, COX 

COMMUNICATIONS KANSAS LLC, COX KANSAS 

TELCOM LLC, COX COMMUNICATIONS GULF 

COAST LLC, COX COMMUNICATIONS LOUISIANA 

LLC, COX LOUISIANA TELCOM LLC, COX 

MARYLAND TELCOM LLC, COX MISSOURI 

TELCOM LLC, COX NEBRASKA TELCOM LLC, 

COX COMMUNICATIONS OMAHA LLC, COX 

COMMUNICATIONS LAS VEGAS INC., COX 

NEVADA TELCOM LLC, COX NORTH CAROLINA 

TELCOM LLC, COX OHIO TELCOM LLC, COX 

OKLAHOMA TELCOM LLC, COX RHODE ISLAND 

TELCOM LLC, COX COMMUNICATIONS 

HAMPTON ROADS, LLC, COX VIRGINIA TELCOM 

LLC,

Plaintiffs-Appellees

v.

SPRINT COMMUNICATION COMPANY LP, 

SPRINT SPECTRUM, L.P., SPRINT SOLUTIONS,

INC.,
 COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION 

COMPANY

2

Defendants-Appellants

CISCO SYSTEMS, INC.,

Defendant

______________________ 

2016-1013

______________________ 

Appeal from the United States District Court for the 

District of Delaware in No. 1:12-cv-00487-SLR, Judge Sue 

L. Robinson.

______________________ 

Decided: September 23, 2016

______________________ 

MICHAEL LOUIS BRODY, Winston & Strawn LLP, Chicago, IL, argued for plaintiffs-appellees. Also represented 

by STEFFEN NATHANAEL JOHNSON, EIMERIC REIG-PLESSIS,

Washington, DC; DAVID SPENCER BLOCH, San Francisco, 

CA; KRISHNAN PADMANABHAN, New York, NY. 

J. MICHAEL JAKES, Finnegan, Henderson, Farabow, 

Garrett & Dunner, LLP, Washington, DC, argued for 

defendants-appellants. Also represented by BASIL TRENT 

WEBB, PETER EMANUEL STRAND, AARON E. HANKEL, JOHN 

D. GARRETSON, RYAN DYKAL, Shook, Hardy & Bacon, LLP, 

Kansas City, MO; ROB RECKERS, Houston, TX.

______________________ 

Before PROST, Chief Judge, NEWMAN and BRYSON, Circuit 

Judges.

Opinion for the court filed by Chief Judge PROST. 

Opinion concurring in the judgment filed by Circuit Judge

NEWMAN. 
COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION

COMPANY

3

PROST, Chief Judge. 

Sprint Communication Company LP and its affiliates 

(collectively, “Sprint”) appeal from a final decision of the 

United States District Court for the District of Delaware 

finding that the asserted claims of U.S. Patent Nos. 

6,452,932; 6,463,052; 6,633,561; 7,286,561; 6,298,064; and 

6,473,429 (collectively, “the asserted patents”) are invalid 

as indefinite under 35 U.S.C. § 112, ¶ 2. Because “processing system” does not prevent the claims, read in light 

of the specification and the prosecution history, from 

informing those skilled in the art about the scope of the 

invention with reasonable certainty, we reverse.

BACKGROUND

The asserted patents relate to developments in voiceover-IP technology. Voice-over-IP allows telephone calls 

to be transmitted over the internet, instead of through 

traditional telephone lines. Voice-over-IP has the ability 

to work with traditional telephone lines, however, such 

that calls initiated on a traditional telephone can be 

converted to packets of information and transmitted over 

the internet. At the receiving end, they are converted 

back to a traditional voice signal.

The asserted patents discuss the hand-off between 

traditional telephone lines (a “narrow-band network” or 

“circuit-switched network”) and a data network (a “broadband network” or “packet-switched network”), such as the 

internet. They can be divided into two groups: U.S. 

Patent Nos. 6,452,932 (“’932 patent”); 6,463,052 (“’052 

patent”); 6,633,561 (“’3,561 patent”); and 7,286,561 

(“’6,561 patent”) (collectively, the “control patents”) share 

a specification, and U.S. Patent Nos. 6,298,064 (“’064

patent”) and 6,473,429 (“’429 patent”) (collectively, the 
 COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION 

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4

“ATM1 interworking patents”) share a different specification. 

Both sets of patents describe the use of a “processing 

system,” which receives a signal from a traditional telephone network and processes information related to that 

voice call to select the path that the voice call should take

through the data network. In the control patents, a 

“communications control processor” (“CCP”) “selects the 

network elements and the connections that comprise the 

communications path.” ’3, 561 patent col. 6 ll. 18–20. In 

the ATM interworking patents, a “signaling processor” 

(or, in preferred embodiments, a “call/connection manager” (“CCM”)) selects the virtual connections by which the 

call will pass through the ATM network and performs 

other call processing functions, such as validation, echo 

control, and billing. ’064 patent col. 4 ll. 47–54, col. 6 ll. 

54–59, col. 7 ll. 13–16. Both specifications disclose that 

logic for selecting a communication path resides in lookup-tables, which the CCP or CCM relies on in making

selection(s). ’3, 561 patent col. 19 ll. 1–27, col. 19 l. 33–

col. 20 l. 6; ’064 patent col. 7 ll. 21–30. 

At issue in this appeal is the definiteness of “processing system” as it is used in the context of the patents. 

Among the control patents, the independent claims at 

issue are: claim 1 of the ’932 patent, claim 1 of the ’052 

patent, claims 1 and 24 of the ’3,561 patent, and claim 11 

of the ’6,561 patent. Claim 1 of the ’3, 561 patent is 

exemplary:

1. A method of operating a processing system to 

control a packet communication system for a user 

communication, the method comprising:

 

1 “ATM” stands for “Asynchronous Transfer Mode,” 

which is a certain type of broadband network that can be 

used in voice-over-IP systems.
COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION

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5

receiving a signaling message for the user communication from a narrowband communication 

system into the processing system; 

processing the signaling message to select a network code that identifies a network element to 

provide egress from the packet communication 

system for the user communication;

generating a control message indicating the network code;

transferring the control message from the processing system to the packet communication system; 

receiving the user communication in the packet 

communication system and using the network 

code to route the user communication through the 

packet communication system to the network element; and

transferring the user communication from the 

network element to provide egress from the packet communication system.

’3, 561 patent col. 22 ll. 12–32 (emphases added).

Among the ATM interworking patents, claim 1 of the 

’064 patent and claim 1 of the ’429 patent are the independent claims at issue. Claim 1 of the ’064 patent is 

exemplary:

1. A communication method for a call comprising:

receiving set-up signaling associated with the call 

into a processing system; 

processing the set-up signaling in the processing 

system to select a DS0 connection;

generating a message identifying the DS0 connection;
 COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION 

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6

transmitting the message from the processing system; 

receiving the message and an asynchronous communication associated with the call into an interworking unit;

in the interworking unit, converting the asynchronous communication into a user communication; and

transferring the user communication from the interworking unit to the DS0 connection in response 

to the message.

’064 patent col. 23 ll. 28–41 (emphases added).

PROCEDURAL HISTORY

This case rests against the backdrop of multi-district 

litigation between these parties and others. On December 

19, 2011, Sprint sued Cox Communications, Inc. and Cox 

Communications Kansas, LLC in the District of Kansas, 

asserting infringement of twelve patents, which included 

the six patents at issue here. That same day, Sprint also 

filed suit against Comcast Cable Communications, Inc. 

(“Comcast”), Cable One, Inc. (“Cable One”), and Time 

Warner Cable Inc. (“Time Warner Cable”) in the District 

of Kansas asserting the same twelve patents. 

On April 16, 2012, Cox Communications, Inc., Cox 

Communications Kansas, LLC, and thirty of their affiliates (collectively, “Cox”) initiated the instant case, filing a 

complaint in the District of Delaware seeking declaratory 

judgment that Sprint’s twelve patents were invalid and 

not infringed. Cox filed a motion to transfer the Kansas 

action to Delaware, which was granted on September 14, 

2012. Sprint consequently counterclaimed for infringement of the twelve patents and several others. 

Sprint’s actions against Comcast, Cable One, and 

Time Warner Cable remained in the District of Kansas 
COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION

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7

and were consolidated for discovery purposes. These 

cases proceeded to claim construction, where on October 

9, 2014, the district court decided, among other things, 

that the term “processing system” was not indefinite, but 

did not warrant a construction. J.A. 838–41.

Approximately four months later, on February 27, 

2015, Cox moved for partial summary judgment in the 

instant case on the grounds that the claim term “processing system” rendered the asserted patents indefinite 

under 35 U.S.C. 112, ¶ 2. On May 15, 2015, the district 

court granted Cox’s motion, finding that the claims were 

indefinite because they “contain[] a structural limitation, 

‘processing system,’” which is “functionally described by 

the claims and in the specifications” and these descriptions “do not pass muster under Nautilus as a person of 

ordinary skill in the art is not provided with the bounds of 

the claimed invention.” J.A. 17–19. The district court 

also found that extrinsic evidence did not save the claims, 

because “there is no ‘established meaning in the art’” for 

“processing system,” because other patents use this term 

in different ways and because the parties did not provide 

(nor could the district court discern, looking at computer 

dictionaries) a definition for “processing system.” J.A. 19.

Sprint appeals the grant of summary judgment of invalidity for indefiniteness. We have jurisdiction under 28 

U.S.C. § 1295(a)(1).

DISCUSSION

We review a district court’s grant of summary judgment that a claim is indefinite de novo, applying the same 

standards as the district court. Ethicon Endo-Surgery, 

Inc. v. U.S. Surgical Corp., 149 F.3d 1309, 1315 (Fed. Cir.

1998). The ultimate conclusion that a claim is indefinite 
 COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION 

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8

under 35 U.S.C. § 112, ¶ 22 is a legal conclusion, which we 

review de novo. Eidos Display, LLC v. AU Optronics 

Corp., 779 F.3d 1360, 1364 (Fed. Cir. 2015). As in claim 

construction, we review a district court’s underlying 

factual determinations for clear error. Id.; see Teva 

Pharm. USA, Inc. v. Sandoz, Inc., 135 S. Ct. 831, 840 

(2015). “Any fact critical to a holding on indefiniteness . . . must be proven by the challenger by clear and 

convincing evidence.” Intel Corp. v. VIA Techs., Inc., 319 

F.3d 1357, 1366 (Fed. Cir. 2003). If indefiniteness can be 

determined based solely on intrinsic evidence, our review 

is de novo. See Teva Pharm. USA, Inc., 135 S. Ct. at 840. 

At the outset, we note that the parties have agreed 

that “processing system” is not a means-plus-function 

term. J.A. 20, n.9. Accordingly, we confine our review to 

the same question presented to the district court: whether 

“processing system” renders the asserted patents indefinite under 35 U.S.C. § 112, ¶ 2. 

Section 112 requires that “[t]he specification shall 

conclude with one or more claims particularly pointing 

out and distinctly claiming the subject matter which the 

inventor or a joint inventor regards as the invention.” 35 

U.S.C. § 112, ¶ 2. This provision strikes a “delicate balance” which recognizes that, although the definiteness 

requirement must tolerate “[s]ome modicum of uncertainty” as “the price of ensuring the appropriate incentives for 

innovation,” Nautilus, Inc. v. Biosig Instruments, Inc., 134 

S. Ct. 2120, 2128–29 (2014) (quoting Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 731 

 

2 The America Invents Act (AIA), Pub. L. No. 112–

29, effective September 16, 2012, has newly designated 

§ 112, ¶ 2 as § 112(b) and § 112, ¶ 6 as § 112(f). Because 

the asserted patents stem from applications that were 

filed before the effective date of the AIA, we will refer to

the pre-AIA versions of these provisions.
COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION

COMPANY

9

(2002)) (internal quotation marks omitted), a patent must 

nevertheless “be precise enough to afford clear notice of 

what is claimed, thereby apprising the public of what is 

still open to them.” Id. (quoting Markman v. Westview 

Instruments, Inc., 517 U.S. 370, 373 (1996)) (internal 

quotation marks omitted). Accordingly, “a patent is 

invalid for indefiniteness if its claims, read in light of the 

specification delineating the patent, and the prosecution 

history, fail to inform, with reasonable certainty, those 

skilled in the art about the scope of the invention.” Id. at 

2129.

This case presents a peculiar scenario: the sole source 

of indefiniteness that Cox complains of, “processing system,” plays no discernable role in defining the scope of the 

claims. All of the asserted claims are method claims, and 

the point of novelty resides with the steps of these methods, not with the machine that performs them. “Processing system” is merely the locus at which the steps are 

being performed. The plain language of the claims proves

this point: if claim 1 of the ’3,561 patent (which the parties agree is exemplary for the control patents) were 

revised to remove the word “processing system,” the 

meaning would not discernably change:
 COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION 

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10

’3,561 patent, claim 1, 

with “processing system”

’3,561 patent, claim 1, 

without “processing 

system” 

1. A method of operating a 

processing system to control 

a packet communication 

system for a user communication, the method comprising:

receiving a signaling message for the user communication from a narrowband 

communication system into 

the processing system; 

processing the signaling 

message to select a network 

code that identifies a network element to provide 

egress from the packet 

communication system for 

the user communication;

. . .

transferring the control 

message from the processing system to the packet 

communication system

. . .

1. A method to control a 

packet communication 

system for a user communication, the method comprising:

receiving a signaling message for the user communication from a narrowband 

communication system;

processing the signaling 

message to select a network 

code that identifies a network element to provide 

egress from the packet 

communication system for 

the user communication;

. . .

transferring the control 

message to the packet 

communication system

. . .

This modification removes the clarification that the 

“processing system” is what performs the “processing” and 

receives and sends certain signals, but even without this

clarification, the same steps would have to be performed. 
COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION

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11

(And, from the nature of the invention, they would have to 

be performed on some kind of computing device.) The

same is true of claim 1 of the ’064 patent (which the 

parties agree is exemplary for the ATM interworking 

patents): 

’064 patent, claim 1, with 

“processing system”

’064 patent, claim 1, 

without “processing 

system” 

1. A communication method 

for a call comprising:

receiving set-up signaling 

associated with the call into 

a processing system; 

processing the set-up 

signaling in the processing 

system to select a DS0 

connection;

. . .

transmitting the message 

from the processing system; 

. . .

1. A communication method 

for a call comprising:

receiving set-up signaling 

associated with the call;

processing the set-up 

signaling to select a DS0 

connection;

. . .

transmitting the message;

. . .

If “processing system” were not omitted but replaced with 

“computer,” a similar conclusion results. Indeed, at oral 

argument, both parties agreed that substituting “computer” for “processing system” would not change the scope of 

the claims. Oral Argument at 10:19–32, 14:57–15:05, 

available at 

http://oralarguments.cafc.uscourts.gov/default.aspx?fl=20

16-1013.mp3 [hereinafter Oral Argument]; see also Oral 
 COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION 

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12

Argument at 11:55–12:18, 14:42–14:57 (acknowledging 

that “processing system” is a general purpose computer).

If “processing system” does not discernably alter the 

scope of the claims, it is difficult to see how this term 

would prevent the claims (the remainder of which Cox 

does not challenge on indefiniteness grounds) from serving their notice function under § 112, ¶ 2. As Nautilus

instructs, the dispositive question in an indefiniteness 

inquiry is whether the “claims,” not particular claim 

terms, “read in light of the specification delineating the 

patent, and the prosecution history, fail to inform, with 

reasonable certainty, those skilled in the art about the 

scope of the invention.”3 134 S. Ct. at 2129. To be sure, 

we have generally acknowledged that an indefiniteness 

analysis under 35 U.S.C. § 112, ¶ 2 is “inextricably intertwined with claim construction.” Atmel Corp. v. Info. 

 

3 The concurrence adopts this same point at base, 

agreeing that Nautilus provides “[t]he operative criterion” 

for questions under § 112, ¶ 2. Concurring Op. at 6. 

Nevertheless, it appears to take great issue with our 

method of analysis, which it interprets as creating a “new 

protocol” that hinges on “deleting the challenged term 

from the claims.” Id. at 2, 6. Our opinion today does no 

such thing. Rather, we compare versions of the claims 

that contain and then exclude “processing system” simply 

as a way of illustrating how Nautilus applies to the claims 

at issue: Nautilus focuses on whether the “claims . . . fail 

to inform,” 134 S. Ct. at 2129, and the comparison reveals 

that this conclusion depends largely on the remainder of 

the claim language, not the “processing system” term. It 

follows then that, because it has little impact on this 

ultimate question, it would be difficult for “processing 

system” to be a source of indefiniteness. This conclusion 

derives only from an application of Nautilus to the claims 

at issue and invites no change to the law of § 112, ¶ 2.
COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION

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13

Storage Devices, Inc., 198 F.3d 1374, 1379 (Fed. Cir. 

1999). Accordingly, the common practice of training 

questions of indefiniteness on individual claim terms is a 

helpful tool. Indeed, if a person of ordinary skill in the art 

cannot discern the scope of a claim with reasonable certainty, it may be because one or several claim terms 

cannot be reliably construed. See, e.g., Interval Licensing 

LLC v. AOL, Inc., 766 F.3d 1364, 1374 (Fed. Cir. 2014) 

(finding the phrase “unobtrusive manner” rendered claims 

indefinite because, even after consulting the claims, 

specification, and prosecution history, a skilled artisan 

would be left “to consult the unpredictable vagaries of any 

one person’s opinion”) (citations and internal quotation 

marks omitted). Nevertheless, indefiniteness under 

§ 112, ¶ 2 must ultimately turn on the question set forth 

by Nautilus: whether the “claims, read in light of the 

specification delineating the patent, and the prosecution 

history, fail to inform, with reasonable certainty, those 

skilled in the art about the scope of the invention.” Id. at 

2129 (emphasis added). Applied here, “processing system” does not prevent the claims from doing just that. 

Cox nevertheless contends that “processing system” is 

indefinite because the asserted claims only describe it in 

functional terms. We disagree. Claims are not per se 

indefinite merely because they contain functional language.4 See also Microprocessor Enhancement Corp. v. 

 

4 We note, however, that in the context of 35 U.S.C. 

§ 112, ¶ 6, we require that, if a patentee writes his claims 

in “means-plus-function” form, he must “disclose the 

particular structure that is used to perform the recited 

function.” Blackboard, Inc. v. Desire2Learn, Inc., 574 

F.3d 1371, 1385 (Fed. Cir. 2009). This is intended to 

avoid “pure functional claiming,” where a patentee 

“claim[s] all possible means of achieving a function.” Id. 

However, by agreeing that “processing system” is not a 
 COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION 

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14

Tex. Instruments Inc., 520 F.3d 1367, 1375 (Fed. Cir. 

2008) (citing Halliburton Energy Servs., Inc. v. M–I LLC, 

514 F.3d 1244, 1255 (Fed. Cir. 2008)) (“[A]pparatus claims 

are not necessarily indefinite for using functional language”). Indeed, here, functional language promotes 

definiteness because it helps bound the scope of the 

claims by specifying the operations that the “processing 

system” must undertake. All of the asserted claims are 

method claims, so it makes sense to define the inventive 

method as a series of functions.

Further, Cox cannot complain that the specific functional limitations that describe the operation of the “processing system” in the asserted patents fail to provide 

sufficient clarity under Nautilus. For example, in the 

control patents, claim 1 of the ’3,561 patent requires that 

the “method of operating a processing system . . . process[es] the signaling message to select a network code 

that identifies a network element to provide egress from 

the packet communication system for the user communi-

 

means-plus-function term, Cox has already conceded that 

“processing system” itself recites sufficiently definite 

structure and there is no problem of “pure functional 

claiming” here. See Williamson v. Citrix Online, LLC, 792 

F.3d 1339, 1348 (Fed. Cir. 2015) (en banc) (“[W]hen a 

claim term lacks the word ‘means,’ . . . § 112, para. 6 will 

apply if the challenger demonstrates that the claim term 

fails to ‘recite[] sufficiently definite structure’ or else 

recites ‘function without reciting sufficient structure for 

performing that function.’” (quoting Watts v. XL Sys., Inc., 

232 F.3d 877, 880 (Fed. Cir. 2000))). Indeed, the claims 

specify that the claimed functions are achieved through 

the use of the “processing system,” which the parties 

agree is, as used in the context of the patents here, a 

general purpose computer. Oral Argument at 11:55–

12:18, 14:42–14:57.
COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION

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15

cation.” The specification discloses, as an embodiment of 

a “processing system,” the CCP and provides details about 

how it functions to “select[] the network elements and the 

connections that comprise the communications path.” 

’3,561 patent col. 6 ll. 23–25. Notably, the specification 

provides certain algorithmic details, including that “selections are made through table look-ups and SCP queries,” 

id. at col. 14 ll. 45–48, and provides detail about how 

these queries are constructed, see, e.g., id. at col. 14 ll. 49–

51, and the types of information that are used to determine these mappings, see, e.g., id. at col. 19 ll. 36–40. 

These disclosures are sufficiently detailed such that, 

reading claim 1 in light of the specification, a person of 

ordinary skill in the art would understand claim 1’s 

requirement that the “method of operating a processing 

system . . . process[es] the signaling message to select a 

network code . . .” with reasonable certainty. 

As another example, in the ATM interworking patents, claim 1 of the ’064 patent requires the step of 

“processing the set-up signaling in the processing system

to select a DS0 connection.” In the specification, the ’064

patent discloses the CCM as an embodiment of a “processing system” and provides details about how it “receive[s] and process[es] . . . signaling to select connections, 

and to generate and transmit signaling identifying the 

selections.” ’064 patent col. 6 ll. 57–59. Similar to the 

specification of the control patents, the specification of the

’064 patent describes that “[t]he selection process can be 

accomplished through table look-ups,” id., col. 7 ll. 20–21, 

and provides detail about how the look-up process happens, see id. at col. 7 ll. 21–30. Accordingly, a person of 

ordinary skill in the art would understand claim 1’s step 

of “processing the set-up signaling in the processing 

system to select a DS0 connection . . .” with reasonable 

certainty.

In sum, “processing system” does not render the 

claims indefinite because it does not prevent the claims, 
 COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION 

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16

read in light of the specification and the prosecution 

history, from informing those skilled in the art about the 

scope of the invention with reasonable certainty. Although the asserted patents describe the operation of the 

“processing system” in largely functional terms, the 

recited steps, read in light of the specification, provide 

sufficient detail such that a person of ordinary skill in the 

art would understand them with reasonable certainty.

CONCLUSION

For the foregoing reasons, we reverse the district 

court’s conclusion that the term “processing system” 

renders the asserted claims indefinite under § 112, ¶ 2. 

REVERSED
United States Court of Appeals 

for the Federal Circuit ______________________ 

COX COMMUNICATIONS, INC., COXCOM, LLC, 

COX ARKANSAS TELCOM LLC, COX 

COMMUNICATIONS ARIZONA LLC, COX ARIZONA 

TELCOM LLC, COX CALIFORNIA TELCOM LLC, 

COX COMMUNICATIONS CALIFORNIA LLC, COX 

COLORADO TELCOM LLC, COX CONNECTICUT 

TELCOM LLC, COX DISTRICT OF COLUMBIA 

TELCOM LLC, COX FLORIDA TELCOM LP, COX 

COMMUNICATIONS GEORGIA LLC, COX 

GEORGIA TELCOM LLC, COX IOWA TELCOM LLC, 

COX IDAHO TELCOM LLC, COX 

COMMUNICATIONS KANSAS LLC, COX KANSAS 

TELCOM LLC, COX COMMUNICATIONS GULF 

COAST LLC, COX COMMUNICATIONS LOUISIANA 

LLC, COX LOUISIANA TELCOM LLC, COX 

MARYLAND TELCOM LLC, COX MISSOURI 

TELCOM LLC, COX NEBRASKA TELCOM LLC, 

COX COMMUNICATIONS OMAHA LLC, COX 

COMMUNICATIONS LAS VEGAS INC., COX 

NEVADA TELCOM LLC, COX NORTH CAROLINA 

TELCOM LLC, COX OHIO TELCOM LLC, COX 

OKLAHOMA TELCOM LLC, COX RHODE ISLAND 

TELCOM LLC, COX COMMUNICATIONS 

HAMPTON ROADS, LLC, COX VIRGINIA TELCOM 

LLC,

Plaintiffs-Appellees

v.

SPRINT COMMUNICATION COMPANY LP, 

SPRINT SPECTRUM, L.P., SPRINT SOLUTIONS,

INC.,
COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION 

COMPANY

2

Defendants-Appellants

CISCO SYSTEMS, INC.,

Defendant

______________________ 

2016-1013

______________________ 

Appeal from the United States District Court for the 

District of Delaware in No. 1:12-cv-00487-SLR, Judge Sue 

L. Robinson.

______________________ 

NEWMAN, Circuit Judge, concurring in the judgment. 

I agree with the court’s holding that the claims are 

not invalid on the ground of indefiniteness. However, the 

court creates an interesting, but flawed, new mode of 

analysis, whereby the adjudicator (1) first removes the 

challenged term from the claim, then (2) decides whether 

the claim has the same meaning without the challenged 

term, and (3) if the answer is “yes,” rules that the claim is 

not indefinite as a matter of law. Maj. Op. at 10–12. This 

new style of claim construction will confound the already 

confused determination of patent rights. I write to protest

this further inroad on a reasoned and reliable law of 

patents.

No precedent supports the court’s new protocol of 

claim construction, whereby definiteness of the claim is 

deemed proved because “if claim 1 of the ’3,561 patent . . . were revised to remove the term “processing 

system,’ the meaning would not discernably change.” 

Maj. Op. at 9. The court criticizes the parties for arguing 

about the indefiniteness of “processing system” as resulting in a “peculiar scenario,” since, in the majority’s view,

the term “processing system,” despite its presence in three 
COX COMMUNICATIONS, INC. v. SPRINT COMMUNICATION

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3

clauses of claim 1 and other claims, “plays no discernable 

role in defining the scope of the claims.” Id. However, 

claim 1 is for a “method of operating a processing system”

by performing the six specified steps in the claim. This is 

not a peculiar scenario.

Cox argues that the term “processing system,” by its 

asserted indefiniteness, “would prevent the 

claims . . . from serving their notice function,” Maj. Op. at 

12, based on the position that the term is not adequately 

supported by structure. The district court so found. The 

court today does not discuss this finding, instead simply 

holding that definiteness is determined by removing the 

challenged term from the claim in order to discover 

whether the claim has the same construction without the 

challenged term. I cannot discern how a claim can have 

the same meaning and scope with and without a critical 

term that limits three clauses of the claim. I show claim 1 

of the ’3,561 patent, with boldface added to the usages of 

“processing system”:

1. A method of operating a processing system to 

control a packet communication system for a user 

communication, the method comprising:

receiving a signaling message for the user communication from a narrowband communication 

system into the processing system; 

processing the signaling message to select a network code that identifies a network element to 

provide egress from the packet communication 

system for the user communication;

generating a control message indicating the network code;

transferring the control message from the processing system to the packet communication 

system;
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receiving the user communication in the packet 

communication system and using the network 

code to route the user communication through the 

packet communication system to the network element; and

transferring the user communication from the 

network element to provide egress from the packet communication system.

’3,561 patent, claim 1 (emphases added). 

I agree with the panel majority that the use of functional terms is not an automatic badge of invalidity, and 

that the context, specification, and knowledge in the art 

must be considered. My concern is with the court’s method of analysis. Functional terms in patents are not prohibited, but they must meet the statutory requirements, 

including:

35 U.S.C. §112(a) In general.— The specification 

shall contain a written description of the invention, and of the manner and practice of making 

and using it, in such full clear, concise, and exact 

terms as to enable an person skilled in the art to 

which it pertains . . . to make and use the same, 

and shall set forth the best mode contemplated by 

the inventor . . . of carrying out the invention.

(b) Conclusion.— The specification shall conclude 

with one or more claims particularly pointing out 

and distinctly claiming the subject matter which 

the inventor . . . regards as the invention.

Here the patentee claimed a method of operating a 

processing system, comprising six steps. The court’s new 

analytical method, whereby the challenged term is removed from the claim and the court then decides whether 

the claim is of the same meaning and scope, Maj. Op. at 
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10–11, is neither legally correct nor plausible.1 I urge the 

court to return to the traditional method of claim analysis.

Under traditional claim analysis, I agree that the 

claims presented for review are not invalid on the ground 

of indefiniteness. The evidentiary record supports the 

conclusion that “processing system” had an understood 

meaning within the telecommunications industry, and the 

expert testimony and publications support the meaning as 

a “system that processes signaling to assist in call control,” Declaration of Stephen B. Wicker, Ph.D, at 32 (J.A. 

989), and that it would be so understood by persons 

having ordinary skill in this field, Supplemental Wicker 

Declaration at 4 (J.A. 997).

The district court ruled that “processing system” is 

indefinite because of insufficient disclosure of the structure that performs each claim step. The district court 

stated that the physical structures were only “functionally 

described by the claims and in the specifications,” that 

they did not provide “a person of ordinary skill in the 

art . . . with the bounds of the claimed invention,” and 

 

1 I take note that the court, while agreeing with the 

parties that the claims before us are not in means-plusfunction form, nonetheless misapplies that law in stating 

that “by agreeing that ‘processing system’ is not a meansplus-function term, Cox has already conceded that ‘processing system’ itself recites sufficiently definite structure 

and there is no problem of ‘pure functional claiming’ 

here.” Maj. Op. at 13–14 n.4. However, agreeing that 

“processing system” is not in means-plus-function form is 

not a concession of structural support. Support is subject 

to analysis on the facts of the particular case, as for every 

invention.
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thus did “not pass muster under Nautilus.” Dist. Ct. Op. 

at 9–10. 

The Nautilus question is whether “a patent’s claims, 

viewed in light of the specification and prosecution history, inform those skilled in the art about the scope of the 

invention with reasonable certainty.” Nautilus, Inc. v. 

Biosig Instruments, Inc., 134 S. Ct. 2120, 2129 (2014). 

The district court stopped short, for this court has elaborated that even for apparatus claims the “recitation 

of . . . function” is “highly relevant to ascertaining the 

boundaries” of a claim. Biosig Instruments, Inc. v. Nautilus, Inc., 783 F.3d 1374, 1383 (Fed. Cir. 2015). We explained that the “claim language, specification, and 

figures” should “provide sufficient clarity to skilled artisans as to the bounds of the disputed term.” Id. at 1382-

83. The district court here focused inappropriately on 

structural limits, whereas these limitations are all steps 

in a method, not an apparatus. The operative criterion is 

whether the claim, read in light of the specification and 

prosecution history, informs skilled artisans of the scope 

of the invention with reasonable certainty. Nautilus, 134 

S. Ct. at 2129. Judicial determination of compliance with 

this requirement is not achieved by deleting the challenged term from the claims.2

When method claims include functional limitations, 

the claims must meet the statutory requirements, including specificity and enablement. There is extensive precedent, in a variety of factual situations, guiding the 

analysis of whether the claim, viewed as a whole, “particularly point[s] out and distinctly claim[s] the subject 

 

2 The Majority states that it “does no such thing,” 

Maj. Op. at 12 n. 3, although the deletions from the claims 

are highlighted on two pages of diagrams “omit[ing]” the 

term, id. at 11, without guidance as to limits, standards, 

and reasoning.
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matter which the inventor or a joint inventor regards as 

the invention.” 35 U.S.C. § 112(b). The inquiry “focuses 

on whether those skilled in the art would understand the 

scope of the claim when the claim is read in light of the 

rest of the specification.” Energizer Holdings, Inc. v. Int’l 

Trade Comm’n, 435 F.3d 1366, 1370 (Fed. Cir. 2006).

Sprint points to the description in the specification, as 

support for the definiteness of the claimed processing 

system. The specification states that the processing 

system “comprises an interface that is external to the 

Switches,” ’3,561 Patent at 3:53–56, with a signaling 

translator, a processor, and associated memory for processing information to select network characteristics. 

’3,561 Patent at 14:16–20 and FIG. 4. The patents describe various known call processing systems in the prior 

art and explain how the claimed system physically connects to various telecommunications systems such as 

Signal Transfer Points, switches, and Service Control 

Points. Flow charts in the specification show interfaces 

and connections, links to other devices and switches and 

operational control systems, and transfers of signals. It is 

noteworthy that Cox does not challenge the individual 

claim steps but concentrates on the overall reference to 

“processing system.”

The evidentiary record and the law lead to the conclusion that the claims were not proved invalid on the 

ground of indefiniteness.3 Although my colleagues today 

reach the correct result, their analytical path is not in 

accordance with law and should be rejected.

 

3 This appeal was taken under Rule 54(b), thus, no 

other issues are before the court, as to either validity or

infringement.