NOTE: This disposition is nonprecedential.

United States Court of Appeals 

for the Federal Circuit ______________________

SPRINT COMMUNICATIONS COMPANY, L.P.,

Plaintiff-Appellee

v.

TIME WARNER CABLE, INC., TIME WARNER 

CABLE, LLC, TIME WARNER ENTERTAINMENT 

COMPANY, L.P., TIME WARNER 

ENTERTAINMENT-ADVANCE/NEWHOUSE 

PARTNERSHIP, TWC COMMUNICATIONS, LLC, 

TIME WARNER CABLE INFORMATION SERVICES 

(KANSAS), LLC,

Defendants-Appellants

______________________

2017-2247

______________________

Appeal from the United States District Court for the 

District of Kansas in No. 2:11-cv-02686-JWL, Judge John 

W. Lungstrum.

______________________

OPINION ISSUED: November 30, 2018

OPINION MODIFIED: March 18, 2019*

______________________

 

* This opinion has been modified and reissued following a petition for en banc rehearing filed by appellants.
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2

J. MICHAEL JAKES, Finnegan, Henderson, Farabow, 

Garrett & Dunner, LLP, Washington, DC, argued for plaintiff-appellee. Also represented by KATHLEEN DALEY, JASON 

LEE ROMRELL; ROB RECKERS, Shook, Hardy & Bacon, LLP, 

Houston, TX; RYAN DYKAL, JOHN D. GARRETSON, BASIL 

TRENT WEBB, Kansas City, MO. 

 JOHN C. O'QUINN, Kirkland & Ellis LLP, Washington, 

DC, argued for defendants-appellants. Also represented by 

MATTHEW PHILIP DOWNER, NATHAN S. MAMMEN, JASON M.

WILCOX; DAVID BENYACAR, DANIEL REISNER, Arnold & Porter Kaye Scholer LLP, New York, NY; RON E. SHULMAN, 

Latham & Watkins LLP, Menlo Park, CA; GABRIEL BELL,

LAWRENCE J. GOTTS, Washington, DC. 

 WILLIAM F. LEE, Wilmer Cutler Pickering Hale and 

Dorr LLP, Boston, MA, for amici curiae Intel Corporation, 

Dell Inc. Also represented by CHRISTOPHER D. DODGE,

MARK CHRISTOPHER FLEMING, LAUREN B. FLETCHER. Amicus curiae Intel Corporation also represented by MATTHEW 

JOHN HULT, Intel Corporation, Santa Clara, CA. Amicus 

curiae Dell Inc. also represented by THOMAS A. BROWN, 

KRISHNENDU GUPTA, Dell Inc., Hopkington, MA.

 ______________________

Before CHEN, MAYER, and BRYSON, Circuit Judges.

Opinion for the court filed by Circuit Judge BRYSON.

Dissenting opinion filed by Circuit Judge MAYER.

BRYSON, Circuit Judge.

This patent infringement case was brought by Sprint 

Communications Company, L.P. (“Sprint”) against Time 

Warner Cable, Inc., and several of its affiliates (collectively, “Time Warner”) in the United States District Court 

for the District of Kansas. Sprint is the owner of the five 

patents-in-suit: U.S. Patent Nos. 6,298,064 (“the ’064 patent”); 6,343,084 (“the ’084 patent”); 6,463,052 (“the ’052 
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patent”); 6,473,429 (“the ’429 patent”); and 6,633,561 (“the 

’561 patent”). Following trial, the jury found all five patents infringed and returned a verdict of approximately 

$140 million in Sprint’s favor. We affirm.

I

The technology at issue in this case involves methods 

for linking circuit-switched and packet-switched networks 

within a telecommunications system. The invention at the 

heart of the patents in suit is a method for using a packetswitched network to transport telephone calls and data to 

and from the existing circuit-switched network for telephone communications known as the Public Switched Telephone Network (“PSTN”). The inventions allowed 

telephone calls and data to be transmitted between those 

two different networks seamlessly.

The traditional PSTN used circuit switching to set up 

an end-to-end path for each call. In a circuit-switched network, a user’s telephone connects to a switch, and the 

switch determines, based on the dialed number, which 

switch will be selected as the next switch in the path. That 

process continues switch-by-switch until the switch that is 

connected to the called party is reached. The signaling between the switches establishes a fixed circuit for the entire 

call, and the call occupies the entire bandwidth of that circuit for the duration of the call.

The traditional circuit-switched technology works well 

for voice communications, but less well for data communication. Because data communication tends to come in 

bursts rather than as a continuous transmission of information, the use of a fixed circuit for data transmission can 

be wasteful of bandwidth during periods in which data is

not being transmitted but the circuit remains active. Accordingly, communications companies developed packetbased solutions to increase the efficiency of data communications. Two types of packet-based technology that are pertinent to this case emerged: (1) asynchronous transfer 
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mode technology (“ATM”), which used “virtual circuits”

that established fixed routes for communications but enabled multiple users to share the circuits at the same time; 

and (2) internet protocol (“IP”) technology, in which each 

IP router in an IP network would make an individual routing decision for each packet based on the ultimate destination of the packet. In the IP system, individual packets 

that are part of a single communication can travel different 

paths to the same destination.

The patents at issue in this case fall into two groups: 

the “call control” patents (the ’052 and ’561 patents) and 

the “broadband” patents (the ’064, ’084, and ’429 patents). 

The call control patents describe methods for telecommunication control of calls to and from the packet-switched 

communication network. The broadband patents address 

the interface between circuit-switched (or “narrowband”) 

networks and packet-switched (or “broadband”) networks. 

Sprint accused Time Warner of infringing the call control 

and broadband patents by using a Voice over Internet Protocol (“VoIP”) service, which converted calls into packet 

data, transmitted the call over an IP network, and provided 

for connectivity to the PSTN. 

II

A. THE ADMISSION OF THE VONAGE VERDICT

Time Warner’s first contention on appeal is that the 

district court improperly permitted Sprint to introduce evidence relating to the jury verdict in an earlier, related case 

brought by Sprint against Vonage, another carrier offering

VoIP service. That case involved the same technology that 

was at issue in this case and resulted in a damages award 

against Vonage. Time Warner contends that the admission 

of the evidence relating to the Vonage verdict prejudiced it 

and requires that it be granted a new trial.

The district court ruled that the Vonage evidence was 

relevant to the jury’s assessment of reasonable royalty 
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damages under a hypothetical negotiation theory. The 

court gave the jury an instruction limiting the use of that 

evidence to the jury’s consideration of the issues of damages and willfulness. 

Although Time Warner argues that the introduction of 

evidence of a jury verdict from another case is invariably 

improper, that is not the rule that this court has applied. 

Instead, the court has held that such evidence can be admissible if it is relevant for some legitimate purpose.

In Applied Medical Resources Corp. v. U.S. Surgical 

Corp., 435 F.3d 1356 (Fed. Cir. 2006), this court affirmed 

the admission of evidence regarding a prior verdict between the parties on the ground that the evidence of that 

verdict was relevant to the hypothetical negotiation between the same parties, which bore on the amount of the 

damages to be awarded under a reasonable royalty theory 

of damages, as well as the issue of willfulness. Id. at 1365–

66. As to the relevance of the prior verdict on the issue of 

damages, the court held that the verdict “was relevant to 

the reasonable royalty analysis because the hypothetical 

negotiation in 1997 took place on the heels of the [prior] 

jury verdict.” Id. at 1366. The court added that the appellant failed to show that the probative value of the evidence 

was outweighed by the danger of unfair prejudice. Id.

The Applied Medical Resources case applied a flexible 

approach to the admission of evidence of prior verdicts or 

other proceedings.1 While such evidence can be prejudicial 

 

1 In its effort to distinguish Applied Medical Resources, Time Warner alludes to the fact that the earlier 

verdict in that case was against the same defendant. But 

that factor would seem to make the risk of prejudice 

stronger, not weaker, as the court explained in Coleman 

Motor Co. v. Chrysler Corp., 525 F.2d 1338, 1351 (3d Cir. 

1975), a case on which Time Warner heavily relies.
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and must be treated with great care, it is admissible if it is 

relevant to a material issue in the case and its use is limited to the purpose for which it is relevant. See Mendenhall 

v. Cedarapids, Inc., 5 F.3d 1557, 1573–74 (Fed. Cir. 1993) 

(evidence of prior litigation “must pass muster, like any 

other evidence, as relevant and probative of an issue in the 

second case”).2 

In this case, the court admitted the prior verdict evidence as relevant to willfulness, to Time Warner’s equitable defenses, and “to the extent that it informs Sprint’s 

executives concerning what [they] might expect as a reasonable royalty.” Thus, as the court explained, the verdict 

would be a factor of which the parties would have been 

aware at the time of their hypothetical negotiation in 2010, 

and a reasonable jury could well conclude that the verdict 

and the amount of damages awarded in a similar prior 

 

2 While Time Warner cites several cases that have 

disapproved of the admission of evidence regarding the outcome of earlier cases, none of those cases is persuasive authority as applied to the circumstances of this case. In 

Engquist v. Oregon Department of Agriculture, 478 F.3d 

985, 1008–09 (9th Cir. 2007), the court held that the district court did not abuse its discretion by excluding evidence of the outcome of a prior proceeding, while noting 

that such evidence is admissible if it is relevant to an issue 

in the later case and is not unfairly prejudicial. In Olitsky 

v. Spencer Gifts, Inc., 964 F.2d 1471, 1475–76 (5th Cir. 

1992), the court held that the evidence of the outcome of 

prior litigation was relevant and that any prejudice was 

cured by an appropriate limiting instruction. Finally, as 

noted, in Coleman Motor Co., the prior verdict was against 

the same defendant, and the court observed that a jury “is 

likely to give a prior verdict against the same defendant 

more weight than it warrants.” 525 F.2d at 1351. 
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litigation would have influenced the outcome of a hypothetical negotiation in the case at bar. 

Importantly, the district court gave the jury limiting 

instructions that the Vonage evidence was to be considered 

only on the issues of damages and willfulness. The court 

gave such an instruction at Time Warner’s request both 

times evidence of the Vonage verdict was introduced and in 

the court’s final jury charge. While the court might have 

given an even more restrictive instruction, no request was 

made for such a further limitation on the instruction given 

to the jury.

Time Warner argues that the differences between the 

Vonage case and this case were such that the district court 

should have excluded the Vonage evidence on relevance 

grounds. We disagree. While there are some differences 

between the two proceedings, the core allegations in both 

were the same. And while Time Warner argues that there 

were several patents raised in each case that were not 

raised in the other, Time Warner has not shown in its briefs 

any reason to believe that the technology asserted in the 

Vonage case was materially different from the technology 

raised in this case. Any differences between the two proceedings, moreover, were available to Time Warner to argue to the jury; the differences did not require exclusion of 

the Vonage verdict.

As for Time Warner’s contention that Sprint’s counsel 

made inflammatory use of the prior verdict before the jury, 

we find that argument to be overstated. The references to 

the jury verdict about which Time Warner complains were

made in the context of a discussion of the hypothetical negotiation. Several of the references were made in Sprint’s 

opening statement. No objection was raised to those remarks as exceeding the limited grounds on which the district court permitted the Vonage evidence to be used. In 

closing argument, Sprint’s counsel again referred to the 

Vonage verdict as it bore on the hypothetical negotiation 
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issue and on the issue of willfulness, as the district court 

had permitted. Having examined each of counsel’s references to the prior verdict, as well as the evidence regarding 

the Vonage verdict that was introduced at trial, we are satisfied that counsel did not make improper or inflammatory 

use of the Vonage evidence, and that the district court did 

not commit reversible error in failing to strike that evidence or prohibit it from being offered for any purpose.

B. THE DAMAGES AWARD

The jury assessed damages against Time Warner in the 

amount of $1.37 per VoIP subscriber per month. Time 

Warner complains that the district court erred in several 

respects in handling the issue of damages.

First, Time Warner contends that, for the same reasons 

that Time Warner objected to the admission of evidence of 

the Vonage verdict, the damages award should be overturned because Sprint’s damages expert relied on that verdict in calculating a reasonable royalty.

 In addition to the previously raised objections to the 

admission of evidence of the Vonage verdict, Time Warner 

argues that the use of the Vonage verdict in the expert’s 

damages calculation was improper because the Vonage verdict was legally flawed. Time Warner argues that Sprint’s 

expert in the Vonage case improperly relied in part on the 

25 percent “rule of thumb” that was frequently used in reasonable royalty cases prior to this court’s decision in Uniloc 

USA, Inc. v. Microsoft Corp., 632 F.3d 1292, 1315 (Fed. Cir. 

2011), which held that “the 25 percent rule of thumb is a 

fundamentally flawed tool,” and that the Vonage verdict 

was therefore tainted.

We have already addressed and rejected Time 

Warner’s arguments regarding the impropriety of admitting evidence of the Vonage verdict. As for Time Warner’s 

argument that the Vonage verdict was tainted by the testimony in that case regarding the 25 percent rule, Sprint’s 
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expert made clear that he was not relying on that rule in 

this case, and the jury in the Vonage case did not return a 

verdict that was based on the 25 percent rule as the measure of damages.

Both parties’ experts explained that the 25 percent rule 

of thumb had been rejected by economists and courts. And 

Time Warner cross-examined Sprint’s damages expert at 

length about the 25 percent rule in an effort to demonstrate 

that the Vonage verdict was tainted by the 25 percent rule 

and was therefore unreliable. In effect, Time Warner is 

now arguing that the references to the 25 percent rule in 

the Vonage case made the verdict in that case per se inadmissible. We disagree. Time Warner had ample opportunity at trial to challenge the reliability of the Vonage 

verdict on that ground. We conclude that Time Warner has 

failed to show that the references to the 25 percent rule in 

the Vonage case had such a demonstrable and substantial 

effect on that case’s verdict as to disqualify the Vonage evidence from consideration by the jury in determining an appropriate damages award in this case. 

Time Warner next argues that the Vonage verdict 

should not have been admitted because the jury in that 

case awarded a royalty based on all of Vonage’s VoIP revenues, without determining which portions of the revenues

were attributed to patented technology as opposed to unpatented features. But the fact that the jury in the Vonage 

case awarded a royalty based on total VoIP revenues does 

not make that verdict inadmissible; the jury in that case 

was called on to make a determination as to the appropriate royalty for the patented technology—the same technology at issue in this case—and it did so in the form of a lump 

sum royalty award. The reasonable royalty award in the 

Vonage case was based on the jury’s determination of the 

value of the technology that was taken as a result of 

Vonage’s infringement. By operation of the hypothetical 

negotiation method of calculating damages, the award compensated Sprint for the incremental value of Sprint’s 
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technology, not for the value of unpatented features of 

Vonage’s VoIP system. 

The evidence showed that the damages award in the 

Vonage case of $1.37 per subscriber per month was approximately five percent of Vonage’s total VoIP revenues for the 

infringement period. The jury settled on the same amount 

for the damages award in this case as in the Vonage case. 

The Vonage verdict did not stand alone, however. In addition to the Vonage verdict, the jury had before it two licenses from Sprint to other communications companies for 

the patented technology, both of which were for approximately five percent of the companies’ VoIP revenue. The 

evidence showed that those licenses, like the Vonage verdict, were based on the value of the patented technology 

and not the value of other aspects of the companies’ VoIP 

technology that were not covered by Sprint’s patents.3

Time Warner argues that Sprint’s damages case was 

flawed because Sprint did not apportion the damages 

award to the incremental value that the patented invention 

added to the end product. See Ericsson, Inc. v. D-Link Sys., 

Inc., 773 F.3d 1201, 1226 (Fed. Cir. 2014). That argument, 

however, ignores that the objective of apportionment can 

be achieved in different ways, one of which is through the 

jury’s determination of an appropriate royalty by applying

the so-called Georgia-Pacific factors, under proper 

 

3 Time Warner contends that each of the other two 

licenses “covers more than the patents Sprint asserts here,” 

Reply Br. 20, but the testimony from Sprint’s expert indicates that those two licenses were for the “same technology” for the “same patents-in-suit” as in the present case. 

As in the case of the Vonage verdict, while those agreements covered numerous patents, Time Warner has not 

shown that the additional patents included technology materially different from the technology covered by the patents-in-suit in this case.
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instructions embodying apportionment principles. See 

Exmark Mfg. Co. v. Briggs & Stratton Power Grp., LLC, 

879 F.3d 1332, 1349 (Fed. Cir. 2018) (“[T]he standard Georgia-Pacific reasonable royalty analysis takes account of the 

importance of the inventive contribution in determining 

the royalty rate that would have emerged from the hypothetical negotiation.” (quoting AstraZeneca AB v. Apotex 

Corp., 782 F.3d 1324, 1338 (Fed. Cir. 2015))); Ericsson, 773 

F.3d at 1228 n.5 (“While factors 9 and 13 of the GeorgiaPacific factors allude to apportionment concepts, we believe a separate instruction culled from Garretson [v. 

Clark, 111 U.S. 120 (1884)] would be preferable in future 

cases.”). 

Such an analysis often considers rates from comparable licenses, and we have explained that “otherwise comparable licenses are not inadmissible solely because they 

express the royalty rate as a percentage of total revenues, 

rather than in terms of the smallest salable unit.” Commonwealth Sci. & Indus. Research Org. v. Cisco Sys., Inc., 

809 F.3d 1295, 1303 (Fed. Cir. 2015). The fact that two 

other licenses were granted for the same technology, together with the Vonage verdict—all of which were for the 

same royalty rate as the rate utilized in the Vonage case to 

yield the $1.37 per VoIP subscriber per month damages assessment—provides strong support for Sprint’s argument 

that the damages award in this case reflected the incremental value of the inventions and thus satisfied the requirement of apportionment. See Ericsson, 773 F.3d at 

1227–28 (damages testimony regarding real-world relevant licenses “takes into account the very types of apportionment principles contemplated in Garretson.”).

Contrary to Time Warner’s contention, the jury’s damages award was based on the value of what was taken from 

Sprint, not the value of unpatented features of Time 

Warner’s VoIP system. Sprint’s damages expert addressed 

apportionment at some length during his testimony, explaining that his damages calculations were designed to 
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determine “the incremental profits that are attributable to 

the patents in suit.” And the jury was specifically instructed on apportionment. The court directed that the 

reasonable royalty “must be based on the incremental 

value that the patented invention adds to the end product. 

When the infringing products have both patented and unpatented features, measuring this value requires a determination of the value added by the patented features.” 

Time Warner did not propose alternative instructions on 

damages, so the issue is simply whether the evidence was 

sufficient to support the jury’s award. In light of the 

Vonage verdict and the other two licenses, as well as testimony from Sprint’s expert as to the cost to Sprint and the 

benefit to Time Warner from Time Warner’s decision to operate the VoIP system itself rather than contracting that 

work out to Sprint, the jury had an adequate basis from 

which to find that damages should be awarded in the 

amount of $1.37 per VoIP subscriber per month.

Finally, Sprint introduced evidence from which the 

jury could conclude that Time Warner did not have available to it any reasonable non-infringing alternatives to 

Sprint’s patented technology for connecting PSTN networks to IP networks. That factor also bears on the amount 

of the royalty that a jury could find would emerge from a 

hypothetical negotiation, as the absence of non-infringing 

alternatives would strengthen the patentee’s hand in such 

a negotiation. See Carnegie Mellon Univ. v. Marvell Tech. 

Grp., Ltd., 807 F.3d 1283, 1304 (Fed. Cir. 2005) (The hypothetical negotiation seeks to determine “what it would have 

been worth to the defendant, as it saw things at the time, 

to obtain the authority to use the patented technology, considering the benefits it would expect to receive from using 

the technology and the alternatives it might have pursued.”). In light of all the evidence bearing on the damages 

award, we conclude that the jury’s verdict was supported 

by sufficient evidence and did not contravene the principles 

of apportionment set forth by this court.
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C. THE WRITTEN DESCRIPTION REQUIREMENT

Time Warner next argues that both the call control patents and the broadband patents were shown to be invalid 

for failure to satisfy the written description requirement 

set forth in 35 U.S.C. § 112, ¶ 1 (now 35 U.S.C. § 112(1)). 

In particular, Time Warner contends that the specifications of each group of patents describe the invention as a 

method of transmitting signals between a PSTN network 

and a packet-switched system that employed Asynchronous Transfer Mode (“ATM”) technology, which used virtual circuits. The specifications, Time Warner argues, do 

not describe the invention as including the transmission of 

signals from a PSTN network to a packet-switched network 

using IP technology. According to Time Warner, the references to “broadband” and “packet” in the specifications disclose only ATM systems and not IP systems.

Compliance with the written description requirement 

presents a question of fact. Ariad Pharms., Inc. v. Eli Lily 

& Co., 598 F.3d 1336, 1355 (Fed. Cir. 2010) (en banc). The 

written description issue was submitted to the jury on instructions that are not objected to on appeal. Through its

verdict, the jury found that the written description requirement was satisfied with respect to both the call control patents and the broadband patents. As to both sets of 

patents, the issue is therefore whether the evidence at trial 

was sufficient to satisfy the written description requirement. Because the common specifications for each of the 

two sets of patents differ significantly, we treat the two invalidity arguments separately.

1. THE CALL CONTROL PATENTS

Time Warner acknowledges that the claims of the call 

control patents cover both ATM and IP communication 

technology. However, Time Warner contends that the common specification of the call control patents is confined to 

ATM technology, and that the claims of the call control patents are invalid because, as applied to IP technology, they 
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are not supported by the specification. Sprint responds 

that the specification is not confined to ATM technology, 

but is broad enough to cover IP technology as well.

IP technology is not expressly excluded from the call 

control specification. Instead, the specification refers to 

“[b]roadband systems, such as Asynchronous Transfer 

Mode (ATM),” ’561 patent, col. 2, ll. 28-30, a formulation 

that strongly suggests that the patents are not limited to

ATM technology. The specification adds that the network 

on which the invention operates “could be any type of telecommunications network that operates using network elements, signaling, and connections.” Id., col. 8, ll. 38-43. 

Importantly, the call control patents disclose means for 

routing communications between a point on a narrowband 

network, such as the PSTN, and a point on a broadband 

network, without specifying whether the point on the 

broadband network is part of a fixed end-to-end path for a 

single call (as in an ATM-based system) or part of a path 

that is established on a packet-by-packet basis by each separate router (as in an IP-based system). See ’561 patent, 

col. 3, ll. 10-20; id., col. 9, line 62, through col. 10, line 39. 

Sprint’s technical expert, Dr. Stephen Wicker, testified 

that a person of skill in the art at the time of the application 

would have understood the use of the term “broadband” to 

include IP as well as ATM technology. He testified that

such a person, reading the common specification of the call 

control patents, would conclude that the inventor “was 

clearly thinking about broadband technologies that used 

routing to individual elements like IP addresses or used 

connections as in ATM.” Dr. Wicker pointed out, for example, that the call control patents state that the communication control processor in the system “processes the 

signaling and selects at least one network characteristic in 

response to the signaling. Network characteristics might 

be network elements, connections, network codes, applications, or control instructions to name a few examples.” ’561 

patent, col. 6, ll. 12-16. 
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Dr. Wicker explained that the reference to “connections” was a reference to ATM technology, while the reference to “network elements” would encompass IP 

technology. Those references, according to Dr. Wicker, 

showed that the call control patents were directed to “something more general in the world of broadband networks 

than just ATM.”

Dr. Wicker focused on the passage from the call control 

patents’ specification that notes that in one embodiment 

the “selection of a network characteristic will include the 

selection of a network code,” and that “network codes are 

the logical addresses of network elements.” Id., col. 12, ll. 

47-56. That passage, he testified, indicates that the specification contemplated the use of IP technology in addition 

to ATM technology, since IP addresses are the logical addresses of network elements.

Dr. Wicker also pointed to a passage in the call control 

specification providing that the call control processor may 

select only network elements and not the connections, and 

that the elements would select the connections to use. Id.,

col. 6, line 62, through col. 7, line 9; see also id., col. 7, ll. 

22-24 (“The [call control processor] might select all the network elements, a portion of the network elements, or none 

of the network elements leaving the switches to select the 

remainder.”); id., col. 15, ll. 32-34. Based on the specification, Dr. Wicker inferred that the inventor was referring to 

“broadband technologies that used routing to individual elements like IP addresses or used connections as in ATM. 

He’s looking at both.” In light of the evidence before the 

jury on the issue, we cannot conclude that Time Warner 

has shown by clear and convincing evidence that the call 

control specification lacks an adequate written description 

to support the asserted claims.

2. THE BROADBAND PATENTS

The common specification of the broadband patents incorporates the specification of the call control patents by 
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reference. For the reasons explained with respect to the 

call control patents, the written description in the broadband patents therefore includes IP technology as well as 

ATM technology. That is so even though the broadband 

specification itself is principally focused on the operation of 

the invention within ATM communication systems.

In addition to noting that the broadband patents incorporate the specification of the call control patents, Dr. 

Wicker pointed to particular portions of the broadband 

specification to support his opinion that the broadband 

specification was not limited to ATM technology with regard to its discussion of the “identifier,” “routing,” and 

“asynchronous communication” elements. As for the identifier, Dr. Wicker testified that a person of ordinary skill 

reading the broadband specification would have concluded 

that the identifier “could be like an IP address pointing to 

a destination, it could be like a VPI/VCI pair pointing to a 

virtual connection. [It is] more general than just saying 

ATM.” The identifier, he concluded, “could cover any 

broadband identifier,” including an IP address. As for 

“routing,” Dr. Wicker testified that routing refers to moving packets toward their destination, with “no limitation on 

how that’s done. . . . [T]he route or routing could be any 

broadband routing including IP.” As for asynchronous 

communication, Dr. Wicker testified that a person of skill 

in the art would understand that term, as used in the 

broadband specification, “to be more general than just a 

particular technology. They would understand it in the 

context of the patents to be a broadband packet switching 

technology but nothing more specific.” In summary, Dr. 

Wicker concluded that the broadband specification was not 

limited to a “fixed path” communication system, such as 

ATM.

We are not persuaded by Time Warner’s argument that 

the district court’s construction of the phrase “interworking 

unit” renders the broadband patent claims invalid. The 

district court construed “interworking unit,” which appears 
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in all asserted claims of the broadband patents, to mean an 

“ATM interworking multiplexer.” Time Warner argues 

that because other claim elements, discussed in the paragraph above, are broad enough to encompass technologies 

other than ATM that are “incongruous with the claimed 

ATM interworking multiplexer,” the claims lack written 

description support. However, Sprint’s expert testified, 

with a reference to technical literature, that ATM and IP 

are actually interoperable such that IP datagrams can be 

transmitted over ATM. Time Warner’s expert agreed that 

it was technically possible to run IP over an ATM network. 

Based on this testimony, a reasonable jury could reject 

Time Warner’s argument that it would be “nonsensical” to 

use IP with an “ATM interworking multiplexer.”

Although the broadband patents focus on ATM technology, we cannot agree, in light of the record at trial, that 

Time Warner has met its burden of showing by clear and 

convincing evidence that the common specification of the 

broadband patents lacks an adequate written description 

of claimed subject matter in those patents.

D. INFRINGEMENT OF THE BROADBAND PATENTS

UNDER THE DOCTRINE OF EQUIVALENTS

Time Warner’s final argument is that the evidence was 

insufficient to support the jury’s verdict that the broadband 

patents were infringed under the doctrine of equivalents. 

The district court construed the term “interworking unit” 

in the broadband patents to mean an “ATM interworking 

multiplexer.”4 Presumably for that reason, the jury found 

that none of the claims of the broadband patents were directly infringed. However, the jury found that those patents were infringed under the doctrine of equivalents.

 

4 On appeal, Time Warner does not challenge the 

trial court’s construction of the broadband patent claims or 

the court’s instructions on the doctrine of equivalents.
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At trial, Sprint introduced evidence that Time 

Warner’s MGX8880 media gateway, which uses an IP card 

to convert data to IP packets, was interchangeable with an 

ATM interworking multiplexer, and therefore satisfied the 

“interworking unit” limitation under the doctrine of equivalents. See Warner-Jenkinson Co. v. Hilton Davis Chem. 

Co., 520 U.S. 17, 36 (1997) (“The known interchangeability 

of substitutes for an element of a patent is one of the express objective factors . . . bearing upon whether the accused device is substantially the same as the patented 

invention.”).

The evidence of interchangeability was sufficient to 

sustain the jury’s verdict. Dr. Wicker testified that the 

MGX8880 was designed with interchangeable cards that 

allowed the medial gateway to handle either ATM or IP 

packets. The fact that swapping cards was possible and 

was contemplated by skilled artisans supports the jury’s 

conclusion that the IP-based system was equivalent to the 

ATM-based system for purposes of the doctrine of equivalents. See Interactive Pictures Corp. v. Infinite Pictures, 

Inc., 274 F.3d 1371, 1383–84 (Fed. Cir. 2001).

To be sure, the evidence showed that converting Time 

Warner’s established network from IP to ATM technology 

would have entailed substantial work and expense. However, the fact that the choice of one of two technologies 

would be expensive to reverse, once the choice was made 

and resources were invested in that choice, does not mean 

that the two competing choices were not equivalent in the 

first instance. Sprint introduced evidence that at the outset the choice between ATM and IP technology, as related 

to the invention set forth in the broadband patents, was 

simply a design choice. That evidence supports the jury’s 

verdict of equivalency.

In addition, Dr. Wicker testified at length regarding 

how Time Warner’s IP system satisfied the function-wayresult test for equivalency for each of the asserted 
SPRINT COMMUNICATIONS COMPANY v. TIME WARNER CABLE,

INC.

19

broadband claims. See Sofamor Danek Grp., Inc. v. DePuyMotech, Inc., 74 F.3d 1216, 1221–22 (Fed. Cir. 1996). He 

explained that the MGX8880 performed the same function 

as the interworking unit recited in the claims, that it did 

so in the same way as the claimed unit, and that it achieved 

the same result. 

Based on the evidence of equivalency adduced at trial, 

we hold that Time Warner has failed to show that the evidence was insufficient to support the jury’s verdict. 

AFFIRMED
NOTE: This disposition is nonprecedential.

United States Court of Appeals 

for the Federal Circuit ______________________

 

SPRINT COMMUNICATIONS COMPANY, L.P.,

Plaintiff-Appellee

v.

TIME WARNER CABLE, INC., TIME WARNER 

CABLE, LLC, TIME WARNER ENTERTAINMENT 

COMPANY, L.P., TIME WARNER 

ENTERTAINMENT-ADVANCE/NEWHOUSE 

PARTNERSHIP, TWC COMMUNICATIONS, LLC, 

TIME WARNER CABLE INFORMATION SERVICES 

(KANSAS), LLC,

Defendants-Appellants

______________________

2017-2247

______________________

MAYER, Circuit Judge, dissenting.

This case involves a remarkable mismatch between 

the narrow patent disclosures and the exceedingly broad 

claims. The patents asserted by Sprint Communications 

Company, L.P. (“Sprint”) are invalid as a matter of law 

because their specifications provide no written description 

support for the full breadth of the asserted claims. I 

therefore respectfully dissent.

The specifications of Sprint’s patents describe ways to 

address the problems that arise when trying to connect 
SPRINT COMMUNICATIONS COMPANY v. TIME WARNER CABLE,

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2

Asynchronous Transfer Mode (“ATM”) systems with the 

traditional Public Switched Telephone Network (“PSTN”). 

J.A. 185–88; see also J.A. 5166–69. The specifications do 

not mention Internet Protocol (“IP”) communications or 

contain any suggestion that methods of establishing 

interconnections between IP networks and the PSTN are 

within the scope of the claimed invention.

The common specification of Sprint’s Call Control Patents, U.S. Patent Nos. 6,463,052 and 6,633,561, describes 

a purportedly novel way of linking ATM networks with 

the PSTN. It discusses establishing fixed end-to-end 

communications paths for calls using PSTN circuits and 

ATM virtual circuits. See, e.g., J.A. 185 (2:28–37), 187 

(5:16–21), 190 (12:35–46). It further discloses a “Communication Control Processor,” which interfaces with the 

switches to set up a fixed end-to-end path for a call. J.A. 

187 (5:30), 190 (11:58–12:4); see also J.A. 177–180.

Importantly, however, the specification contains no 

disclosure of IP technology, which operates in a fundamentally different way than ATM technology. Unlike an 

ATM network, an IP network does not use circuits or 

virtual circuits and does not set up a fixed path for a call. 

See J.A. 3872–73, 4414–15. To the contrary, each packet 

with data for a call is routed using an identifier in the 

packet known as an “IP address.” See J.A. 3872–73. As 

an expert for Time Warner Cable, Inc. and related parties 

explained, ATM is “like being on a train track where you 

have to follow the tracks,” but IP is like “driving a car 

from Point A to [Point] B, where you’re free to take different roads.” J.A. 4827–28; see also J.A. 4413–15. The 

common specification of the Call Control Patents does not 

contain any disclosure of IP technology, which is unsurprising given that it is directed to setting up fixed end-toend communications paths and IP routing does not rely on 

such paths.
SPRINT COMMUNICATIONS COMPANY v. TIME WARNER CABLE,

INC. 3

Sprint argues that its “Call Control Patents disclose 

inventions for routing communications between a point on 

a narrowband network and a point on a broadband network, without regard for whether the point in a broadband network is part of a fixed path or is established on a 

call-by-call basis.” Br. of Plaintiff-Appellee at 56. In 

support, it contends that the common specification of the 

Call Control Patents “describe[s] a flexible processing 

system that may select ‘all,’ ‘a portion,’ or ‘none’ of the 

network elements, as well as ‘all,’ ‘a portion,’ or ‘none’ of 

the connections, in performing the steps of the claims.” 

Id. (quoting J.A. 188 (7:22–29)). In essence, Sprint argues 

that the specification does not require the selection of all 

of the network elements and connections in a communications path. This argument fails. The common specification makes clear that the Communication Control 

Processor and the switches will function together to select 

all of the network elements and connections. See J.A. 188 

(7:20–29) (“One skilled in the art will recognize that the 

selection process can be distributed among the [Communication Control Processor] and the elements. The [Communication Control Processor] might select all the 

network elements, a portion of the network elements, or 

none of the network elements leaving the switches to select

the remainder.” (emphasis added)). Over and over again, 

the specification refers to establishing a communications 

path. See, e.g., J.A. 185 (1:37–46), 186 (3:15–18), 190 

(11:35–36). It contains nothing even arguably suggesting 

that a fixed communications path will not be established, 

as would be the case if the claimed invention encompassed IP technology.

Like its Call Control Patents, Sprint’s Broadband Patents, U.S. Patent Nos. 6,343,084, 6,473,429, and 

6,298,064, lack written description support. The purported invention described in the common specification of the 

Broadband Patents is an alternative technique for including both PSTN circuits and virtual circuits in the same 
SPRINT COMMUNICATIONS COMPANY v. TIME WARNER CABLE,

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4

communications path. See J.A. 303–05. The specification’s disclosure makes sense only in the context of ATM 

technology. The common specification does not disclose 

any packet identifiers other than ATM VPI/VCI identifiers, any routing other than ATM routing, or any form of 

asynchronous communication other than ATM. See J.A. 

242–53. Importantly, moreover, all of the claims of the 

Broadband Patents, as construed by the district court, 

require an “ATM interworking multiplexer.” J.A. 352–55. 

There is no dispute that an ATM interworking multiplexer converts calls between PSTN and ATM formats, allowing the two types of networks to be bridged. J.A. 3689; see 

also J.A. 3863, 4485–86, 5280–81. Nothing in the common specification suggests or even hints that converting 

to and from IP or routing over an IP network is within the 

scope of the claimed invention.

Sprint attempts to salvage the verdict of no invalidity 

by arguing that the jury was entitled to rely on the testimony of its expert, Dr. Steven Wicker, who stated that the 

asserted patents met the written description requirement. 

See J.A. 5638–43, 5647–50, 5670–76. This argument is 

unpersuasive. Wicker’s statements were conclusory and 

unsupported by any persuasive citation to the patent 

disclosures or other record evidence. See, e.g., ActiveVideo 

Networks, Inc. v. Verizon Commc’ns, Inc., 694 F.3d 1312, 

1327 (Fed. Cir. 2012) (declining to credit expert testimony 

that “was conclusory and factually unsupported”).

Wicker argued that IP networks are within the scope 

of the claimed invention because there are technologies 

that can “force” an IP network to set up and use a fixed 

communications path. See J.A. 5738–39, 5651–56. This 

argument is premised on a misapprehension of the adequate written description requirement. The salient 

question “is whether the disclosure . . . reasonably conveys to those skilled in the art that the inventor had 

possession of the claimed subject matter as of the filing 

date,” Ariad Pharm., Inc. v. Eli Lilly & Co., 598 F.3d 
SPRINT COMMUNICATIONS COMPANY v. TIME WARNER CABLE,

INC. 5

1336, 1351 (Fed. Cir. 2010) (en banc), not whether an 

undisclosed technology can be “forced” to operate within 

the disclosed system. See Lockwood v. Am. Airlines, Inc., 

107 F.3d 1565, 1572 (Fed. Cir. 1997) (“It is not sufficient 

for purposes of the written description requirement of 

§ 112 that the disclosure, when combined with the 

knowledge in the art, would lead one to speculate as to 

[the] modifications that the inventor might have envisioned, but failed to disclose.”).

“[T]he purpose of the written description requirement 

is to ensure that the scope of the right to exclude, as set 

forth in the claims, does not overreach the scope of the 

inventor’s contribution to the field of art as described in 

the patent specification.” Ariad, 598 F.3d at 1353–54 

(citations and internal quotation marks omitted). Sprint 

overreaches here. It seeks broad monopoly rights over 

interconnections between narrowband and broadband 

networks. Nothing in the patent specifications, however, 

is sufficient to sweep non-path technologies like IP within 

the scope of the claimed invention. See Gentry Gallery, 

Inc. v. Berkline Corp., 134 F.3d 1473, 1480 (Fed. Cir. 

1998) (explaining that “claims may be no broader than the 

supporting disclosure”). I would reverse.