Twilio Inc. v. Telesign Corporation

NOTE: This disposition is nonprecedential.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
______________________

S
ARAH 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, Kan-
sas City, MO, for appellee. Also represented by CHRISTINE
A. GUASTELLO, MARY PEAL.
______________________

Case: 19-1842 Document: 59 Page: 1 Filed: 06/10/2020

TWILIO INC. v. TELESIGN CORPORATION
2
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 obvi-
ous. 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 meth-
ods for processing telephony sessions that involve com-
municating with an application server and accessing call
router resources through an application programming in-
terface (API). See ’376 patent at 1:60–66; ’465 patent at
1:60–66. The Board held that the combination of U.S. Pa-
tent 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 sub-
stantial 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 find-
ings related to the Jiang reference or the other grounds on
appeal.
Case: 19-1842 Document: 59 Page: 2 Filed: 06/10/2020

TWILIO INC. v. TELESIGN CORPORATION
3
decisions if they are “arbitrary, capricious, an abuse of dis-
cretion, 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 com-
municating with an application server by initiating a te-
lephony 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 re-
sponse 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 con-
nected system cooperatively with a plurality of ap-
plication programming Interface (API) resources,
wherein operating the system comprises:
initiating a telephony session,
communicating with an application server to re-
ceive 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 lim-
itations of claim 1. It does not separately challenge the
Board’s findings related to any of the dependent claims.
Case: 19-1842 Document: 59 Page: 3 Filed: 06/10/2020

TWILIO INC. v. TELESIGN CORPORATION
4
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 re-
quest 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 ar-
gues that the Board erred in its analysis of the responding
limitation and in its construction of the term “API re-
source.” It further challenges the Board’s motivation-to-
combine 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 re-
jected 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.
Case: 19-1842 Document: 59 Page: 4 Filed: 06/10/2020

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 evi-
dence. Maes teaches a system with an “audio I/O subsys-
tem (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 “capa-
ble 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 rec-
ord are part of the request, number of bytes played/rec-
orded, 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 un-
derstand 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 limita-
tion.
Twilio argues the Board improperly modified the
grounds raised in Telesign’s petition by combining Ransom
with Maes to teach the responding limitation when Tele-
sign’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 the-
ory,” such is not the case here. Sirona Dental Sys. GmbH
v. Institut Straumann AG, 892 F.3d 1349, 1356 (Fed. Cir.
Case: 19-1842 Document: 59 Page: 5 Filed: 06/10/2020

TWILIO INC. v. TELESIGN CORPORATION
6
2018). Telesign argued in its petition that the combination
of Maes and Ransom teaches the claim limitations, includ-
ing both the requesting and responding limitations. Tele-
sign specifically argued that Maes teaches a REST API
request that specifies a resource URI, and teaches a re-
sponse to that same request. J.A. 6361–64. It further ar-
gued 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. Accord-
ingly, 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 demon-
strate 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 ex-
cept for necessary subsidiary factual findings based on ex-
trinsic 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 re-
source 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 construc-
tion. Twilio, however, argued the construction should fur-
ther include a requirement that the API resource be
Case: 19-1842 Document: 59 Page: 6 Filed: 06/10/2020

TWILIO INC. v. TELESIGN CORPORATION
7
identifiable by its URI, for purposes of the operating limi-
tation. The Board rejected Twilio’s argument “[b]ecause
claim 1 separately recites a URI that identifies an API re-
source” 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 re-
sources—“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 be-
cause 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 inter-
face 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 un-
derstand 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 sup-
port its position that an API must be identifiable by its
URI. Appellant’s Opening Br. at 38.
Case: 19-1842 Document: 59 Page: 7 Filed: 06/10/2020

TWILIO INC. v. TELESIGN CORPORATION
8
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. Sub-
stantial evidence supports the Board’s motivation-to-com-
bine finding.
2. The ’465 Patent
Like the ’376 patent, the ’465 patent generally relates
to a method and system that allow development of teleph-
ony 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 te-
lephony 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 appli-
cations. Claim 1 of the ’465 patent is illustrative:
5

1. A method for processing a telephony communi-
cation comprising:
associating an initial URI with a telephony end-
point;
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 lim-
itations of claim 1 of the ’465 patent.
Case: 19-1842 Document: 59 Page: 8 Filed: 06/10/2020

TWILIO INC. v. TELESIGN CORPORATION
9
embedding state information of the telephony voice
session in the request;
receiving a response to the application layer proto-
col request sent to the application resource,
wherein the response includes a document of te-
lephony 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 “de-
fines the resource that is being accessed,” and that it was
well known to send information over the Internet to an ap-
plication using a URI. J.A. 5282 at [0162]–[0163]. The ap-
plication, which may be defined by a URI, is mapped to the
telephony session when it is assigned to take the call and
Case: 19-1842 Document: 59 Page: 9 Filed: 06/10/2020

TWILIO INC. v. TELESIGN CORPORATION
10
when the TEL address (the telephony gateway address con-
taining 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 “assign-
ing an application specified by a URI to incoming call in-
formation (i.e., a telephony endpoint), thereby associating
a URI with a telephony endpoint,” which meets the map-
ping 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 appli-
cation 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 posi-
tion, Maes teaches passing the TEL address to the applica-
tion 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 call-
ers, and/or any suitable data.” J.A. 18; ’465 patent at 5:33–

6
Twilio separately argues that even if the TEL ad-
dress 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).
Case: 19-1842 Document: 59 Page: 10 Filed: 06/10/2020

TWILIO INC. v. TELESIGN CORPORATION
11
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 ar-
ticulate 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 ap-
plication over the Internet, as disclosed in Maes. J.A. 26.
The Board was not relying on Ransom to modify the archi-
tecture disclosed in Maes, but instead to show that the com-
bination expressly teaches using a URI to achieve the
embodiment claimed in the ’465 patent. As Dr. Nielson ex-
plained, 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 evi-
dence supports the Board’s finding that a person of ordi-
nary 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.
C
ONCLUSION
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
Case: 19-1842 Document: 59 Page: 11 Filed: 06/10/2020