Document ID: s3://data.kl3m.ai/documents/govinfo/USCOURTS/USCOURTS-ca13-19-01843/USCOURTS-ca13-19-01843-0/pdf.json

Parties Involved:
TeleSign Corporation
Appellee
Twilio Inc.
Appellant

Document Text:

NOTE: This disposition is nonprecedential.

United States Court of Appeals 

for the Federal Circuit ______________________

TWILIO INC.,

Appellant

v.

TELESIGN CORPORATION,

Appellee

______________________

2019-1842, 2019-1843

______________________

Appeals from the United States Patent and Trademark 

Office, Patent Trial and Appeal Board in Nos. IPR2017-

01976, IPR2017-01977.

______________________

Decided: June 10, 2020

______________________

SARAH J. GUSKE, Baker Botts LLP, San Francisco, CA, 

for appellant. Also represented by THOMAS B. CARTER, JR., 

MICHELLE JACOBSON EBER, Houston, TX; LAUREN J.

DREYER, Washington, DC. 

 JESSE J. CAMACHO, Shook, Hardy & Bacon, LLP, Kansas City, MO, for appellee. Also represented by CHRISTINE 

A. GUASTELLO, MARY PEAL. 

 ______________________

Case: 19-1843 Document: 6 Page: 1 Filed: 06/10/2020
2 TWILIO INC. v. TELESIGN CORPORATION

Before MOORE, O’MALLEY, and HUGHES, Circuit Judges.

MOORE, Circuit Judge.

Twilio Inc. appeals the Patent Trial and Appeal Board’s 

inter partes review decisions holding claims 1–3, 5, 14, 16, 

17, and 19 of U.S. Patent No. 8,755,376 and claims 1–6, 9, 

and 13 of U.S. Patent No. 8,837,465 unpatentable as obvious. Because the Board’s decisions were not erroneous and 

substantial evidence supports its findings, we affirm.

The ’376 and ’465 patents relate to systems and methods for processing telephony sessions that involve communicating with an application server and accessing call 

router resources through an application programming interface (API). See ’376 patent at 1:60–66; ’465 patent at 

1:60–66. The Board held that the combination of U.S. Patent No. 6,801,604 (Maes) and U.S. Patent Pub. 

No. 2003/0204756 (Ransom) rendered the challenged 

claims unpatentable as obvious.1 Twilio appeals. We have 

jurisdiction under 28 U.S.C. § 1295(a)(4)(A). 

DISCUSSION

We review the Board’s factual determinations for substantial evidence and its legal determinations de novo.

Outdry Techs. Corp. v. Geox S.p.A., 859 F.3d 1364, 1367 

(Fed. Cir. 2017). Obviousness is a question of law, which is 

based on underlying factual findings. Id. We review the 

Board’s procedures for compliance with the Administrative 

Procedure Act (APA) de novo, and we must set aside Board 

1 Telesign’s petition challenging the ’376 patent 

claims included a third reference—U.S. Patent No. 

7,092,370 (Jiang)—to render dependent claims 5 and 17 

unpatentable as obvious. Telesign’s petitions also included 

other grounds. Twilio does not challenge the Board’s findings related to the Jiang reference or the other grounds on 

appeal. 

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TWILIO INC. v. TELESIGN CORPORATION 3

decisions if they are “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law.” 5 U.S.C. 

§ 706; EmeraChem Holdings, LLC v. Volkswagen Grp. of 

Am., Inc., 859 F.3d 1341, 1345 (Fed. Cir. 2017).

1. The ’376 Patent

The ’376 patent relates to methods and systems that 

allow development of telephony applications using existing 

web development tools and resources. ’376 patent at 1:61–

2:6. Specifically, the ’376 patent discloses a method of communicating with an application server by initiating a telephony session, mapping a call to a Universal Resource 

Identifier (URI), sending a request to the server associated 

with the URI, processing the request, and receiving a response from the server. Id. at 2:57–65. Claim 1 of the ’376 

patent is illustrative:2

1. A method comprising:

operating a telephony network and internet connected system cooperatively with a plurality of application programming Interface (API) resources, 

wherein operating the system comprises:

initiating a telephony session,

communicating with an application server to receive an application response,

converting the application response into executable 

operations to process the telephony session,

creating at least one informational API resource; 

and

2 Twilio’s challenges on appeal are limited to the limitations of claim 1. It does not separately challenge the 

Board’s findings related to any of the dependent claims.

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4 TWILIO INC. v. TELESIGN CORPORATION

exposing the plurality of API resources through a 

representational state transfer (REST) API that 

comprises:

receiving a REST API request that specifies an API 

resource URI, and

responding to the API request according to the request and the specified resource URI.

(emphasis added). The Board held claims 1–3, 5, 14, 16, 

17, and 19 of the ’376 patent unpatentable as obvious in 

view of the combination of Maes and Ransom.3 Twilio argues that the Board erred in its analysis of the responding 

limitation and in its construction of the term “API resource.” It further challenges the Board’s motivation-tocombine finding. As discussed below, we hold that the 

Board did not err in its analysis and substantial evidence

supports its findings. 

A. The Responding Limitation

The Board determined “that the combination of Maes 

and Ransom teaches responding to the REST API request 

according to the specified API resource URI.” J.A. 60. It 

found that Maes teaches that a “telephony gateway, 

TEL 20, responds to an API request that specifies an API 

resource, such as ‘MakeCall,’ ‘TransferCall,’ or ‘Record,’ by 

modifying the state of a telephony session according to the 

request and the specified resource, such as by initiating, 

transferring, or recording a call.” J.A. 59. The Board rejected Twilio’s argument that those portions of Maes do not 

teach responding to an API request according to a specified 

3 As discussed above, the Board further relied on 

Jiang to supports its holding that dependent claims 5 and 

17 were obvious. Because Twilio only challenges the 

Board’s decisions as they relate to Maes and Ransom, we 

need not separately consider Jiang.

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TWILIO INC. v. TELESIGN CORPORATION 5

URI, finding that Maes teaches that the response may be 

to a single specified source. And the Board found that 

“Ransom teaches that an API request can be a REST API 

request that specifies an API resource URI.” J.A. 60. 

The Board’s findings are based on substantial evidence. Maes teaches a system with an “audio I/O subsystem (or ‘TEL’)” which “comprises a gateway (e.g., telephony 

platform) that connects voice audio streams from a network 

to the various speech engines.” J.A. 5214–15 at 8:51–52, 

9:5–7. It further teaches that the TEL component is “capable of receiving the HTTP/SOAP requests” and is capable 

of responding to those requests. J.A. 5227 at 34:7–35:8. 

Moreover, Maes teaches, for example, “[i]f play and/or record are part of the request, number of bytes played/recorded, number of overruns/underruns, completion 

reason, . . . play/record start/stop time . . . are included in 

the response.” J.A. 5228 at 35:25–28. Thus, Maes teaches 

responding to API requests according to the request and 

the specified source. Ransom teaches that REST and 

SOAP “are two common web service models wherein HTTP 

is the underlying application protocol” and in the REST 

model, “the service being invoked is the URI being accessed 

through the web.” J.A. 5282 at [0163]. Therefore, as the 

Board found, a person of ordinary skill in the art would understand that the HTTP/SOAP requests taught in Maes

could instead be a REST API request with a specific URI, 

as taught in Ransom, resulting in the responding limitation.

Twilio argues the Board improperly modified the 

grounds raised in Telesign’s petition by combining Ransom 

with Maes to teach the responding limitation when Telesign’s petition never referenced Ransom’s teachings with 

respect to that claim limitation. While it is true that it 

would “not be proper for the Board to deviate from the 

grounds in the petition and raise its own obviousness theory,” such is not the case here. Sirona Dental Sys. GmbH 

v. Institut Straumann AG, 892 F.3d 1349, 1356 (Fed. Cir. 

Case: 19-1843 Document: 6 Page: 5 Filed: 06/10/2020
6 TWILIO INC. v. TELESIGN CORPORATION

2018). Telesign argued in its petition that the combination 

of Maes and Ransom teaches the claim limitations, including both the requesting and responding limitations. Telesign specifically argued that Maes teaches a REST API 

request that specifies a resource URI, and teaches a response to that same request. J.A. 6361–64. It further argued that to the extent Maes does not teach a REST API 

request that specifies a URI, Ransom teaches that such a 

request was well known in the art. J.A. 6361–62. Accordingly, the Board found that Maes teaches responding to an 

API request and that Ransom teaches the API request can 

be a REST API request that specifies an API resource URI. 

J.A. 60. Telesign’s petition relies on Ransom to demonstrate that an API request can be a REST API request that 

specifies an API resource URI, which applies for both the 

requesting and responding limitations, and supports the 

Board’s findings related to the “responding” limitation. We 

hold therefore that the Board did not modify the grounds 

asserted in the petition, and substantial evidence supports 

the Board’s findings.

B. API Resource

We review the Board’s claim construction de novo except for necessary subsidiary factual findings based on extrinsic evidence, which we review for substantial evidence. 

Acceleration Bay, LLC v. Activision Blizzard Inc., 908 F.3d 

765, 769 (Fed. Cir. 2018). The Board construed the term 

“application programming interface (API) resource” in the 

operating clause as “a resource available through an API.” 

J.A. 8. 

Twilio argues the Board erred in its construction and 

obviousness analysis by not requiring that the API resource be identifiable by its URI. We do not agree. As an 

initial matter, the parties agreed that an API resource is a 

resource available through an API—the Board’s construction. Twilio, however, argued the construction should further include a requirement that the API resource be 

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TWILIO INC. v. TELESIGN CORPORATION 7

identifiable by its URI, for purposes of the operating limitation. The Board rejected Twilio’s argument “[b]ecause 

claim 1 separately recites a URI that identifies an API resource” in the receiving limitation. J.A. 8. We agree with 

the Board’s construction. Under the broadest reasonable 

interpretation standard, which applies here, nothing in the 

claim or specification limits the API resource as it is used 

in the operating limitation.4 The ’376 patent’s specification

supports the Board’s rejection of Twilio’s argument because 

the specification contemplates a broad scope of API resources—“any suitable commands or methods may be used 

to interface with an API resource.” ’376 patent at 8:65–9:1. 

Accordingly, we find no error in the Board’s construction.

C. Motivation to Combine

The Board found that a person of ordinary skill in the 

art would have been motivated to combine the teachings of 

Maes and Ransom. J.A. 66–71. Twilio argues that the 

Board’s finding that the references could be combined 

lacked any explanation for why a person of ordinary skill 

in the art would combine them. We do not agree. As the 

Board explained, “it would have been obvious under KSR

to combine the cited teachings of Maes and Ransom because Ransom’s REST API is a common web service model 

that provides similar functionality and has several design 

advantages over Maes’ SOAP API, such as increased interface flexibility and lower bandwidth requirements.” 

J.A. 68. Documentary evidence and the declaration of Dr. 

Nielson, Telesign’s expert, supported the Board’s finding. 

See J.A. 5493–95, 5499–5500. Dr. Nielson explained that 

“[a] skilled artisan with a preference for REST would understand that using REST conventions instead of SOAP to 

4 Indeed, Twilio points to the same language in claim 

1 that the Board held would be deemed redundant to support its position that an API must be identifiable by its 

URI. Appellant’s Opening Br. at 38. 

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8 TWILIO INC. v. TELESIGN CORPORATION

implement a web service API would be straight forward 

and with an almost certain chance of success.” J.A. 5493. 

He then explained that a person of skill in the art would be 

motivated to make such a modification because “REST has 

a flexible interface and requests and responses can be 

short, resulting in lower bandwidth consumption,” and 

“that it is lightweight, has human readable results, and is 

easy to build with no toolkits required.” J.A. 5494. Substantial evidence supports the Board’s motivation-to-combine finding.

2. The ’465 Patent

Like the ’376 patent, the ’465 patent generally relates 

to a method and system that allow development of telephony applications using existing web development tools and 

resources. ’465 patent at 1:61–2:3. The claims of the ’465 

patent specifically relate to a method of processing a telephony communication involving mapping of a URI, which 

allows a telephony session to be converted into a format 

that may be handled with standard web servers and applications. Claim 1 of the ’465 patent is illustrative:5 

1. A method for processing a telephony communication comprising: 

associating an initial URI with a telephony endpoint;

initiating a telephony voice session for a telephony 

communication to the telephony endpoint;

mapping the initial URI to the telephony session;

sending an application layer protocol request to an 

application resource specified by the URI and 

5 Twilio’s challenges on appeal are limited to the limitations of claim 1 of the ’465 patent.

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embedding state information of the telephony voice 

session in the request;

receiving a response to the application layer protocol request sent to the application resource, 

wherein the response includes a document of telephony instructions; and

executing telephony actions during the telephony 

voice session according to a sequential processing 

of at least a subset of the telephony instructions of 

the response.

(emphasis added). The Board held claims 1–6, 9, and 13 of 

the ’465 patent obvious in view of the combination of Maes 

and Ransom. Twilio argues that substantial evidence does 

not support the Board’s findings that the mapping and 

sending limitations were taught by the combination of 

Maes and Ransom, or that a person of ordinary skill in the 

art would have been motivated to combine the references. 

Substantial evidence supports the Board’s findings.

A. The Mapping Limitation

The Board found that “the combination of Maes and 

Ransom teaches sending a message that includes both the 

URI specifying the assigned application and information 

about the telephony session, thereby mapping the URI to 

the telephony session.” J.A. 13. Twilio argues that the 

Board did not address how Maes’ message to an application 

maps the initial URI to the telephony session. We do not 

agree. Maes teaches assigning an application to take a call, 

and when the application is assigned, the TEL address is 

passed to the application for the duration of the call. 

J.A. 5218 at 15:58–62. Ransom teaches that the URI “defines the resource that is being accessed,” and that it was 

well known to send information over the Internet to an application using a URI. J.A. 5282 at [0162]–[0163]. The application, which may be defined by a URI, is mapped to the 

telephony session when it is assigned to take the call and 

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10 TWILIO INC. v. TELESIGN CORPORATION

when the TEL address (the telephony gateway address containing information about the telephony session) is passed 

to the same application for the call’s duration. In other 

words, the combination of Maes and Ransom teach “assigning an application specified by a URI to incoming call information (i.e., a telephony endpoint), thereby associating 

a URI with a telephony endpoint,” which meets the mapping limitation. J.A. 17. Accordingly, we conclude that 

substantial evidence supports the Board’s finding. 

B. The Sending Limitation

The Board found that Maes teaches “sending an application layer protocol request to an application resource 

specified by the URI and embedding state information of 

the telephony voice session in the request” as required by 

claim 1. J.A. 15. Twilio argues that substantial evidence 

does not support the Board’s finding because Maes does not 

teach or suggest that the duration of the call is “embedd[ed] 

state information” as claimed.6 Contrary to Twilio’s position, Maes teaches passing the TEL address to the application for the duration of the call. J.A. 5218 at 15:58–62. The 

Board found that the TEL address, which is the telephony 

gateway address, is state information akin to the examples 

of state information referenced in the ’465 patent—“[s]tate 

information included with each request may include a 

unique call identifier, call status data such as whether the 

call is in-progress or completed, the caller ID of the caller, 

the phone number called, geographic data about the callers, and/or any suitable data.” J.A. 18; ’465 patent at 5:33–

6 Twilio separately argues that even if the TEL address is state information, it was not “embedded” within 

the request. We hold that Twilio waived this argument by 

failing to raise it before the Board, and we will not consider 

it for the first time on appeal. See HTC Corp. v. Cellular 

Commc’ns Equip., LLC, 877 F.3d 1361, 1368 n.3 (Fed. Cir. 

2017). 

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37. Because Maes teaches passing the TEL address to the 

application for the duration of the call, we conclude that 

substantial evidence supports the Board’s finding that 

Maes teaches the sending limitation.

C. Motivation to Combine

The Board found that a person of ordinary skill in the 

art would be motivated to combine Maes and Ransom to 

achieve the invention claimed in the ’495 patent. J.A. 24–

26. Twilio argues that the Board failed to sufficiently articulate a motivation to combine Maes with Ransom to 

achieve the associating and mapping limitations in claim 

1. We conclude that substantial evidence supports the 

Board’s motivation-to-combine finding. The Board found 

that a person of ordinary skill in the art would understand 

Ransom as explicit support of the understanding that it 

was well known to use a URI to send a message to an application over the Internet, as disclosed in Maes. J.A. 26. 

The Board was not relying on Ransom to modify the architecture disclosed in Maes, but instead to show that the combination expressly teaches using a URI to achieve the 

embodiment claimed in the ’465 patent. As Dr. Nielson explained, a person of ordinary skill in the art would consider 

Ransom’s express disclosure of use of URIs to better 

achieve Maes’ goals of using Web APIs and Internet-based 

technologies. See J.A. 5417. Accordingly, substantial evidence supports the Board’s finding that a person of ordinary skill in the art would be motivated to consider Maes 

and Ransom as a combination that expressly discloses the 

limitations of claim 1 of the ’465 patent. 

CONCLUSION

We have considered the parties’ remaining arguments 

and find them unpersuasive. Because the Board did not 

err in its analyses and substantial evidence supports the 

Board’s findings, we affirm.

AFFIRMED

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