EXHIBIT 19

Case 2:23-cv-00444-JRG Document 1-20 Filed 09/27/23 Page 1 of 12 PageID #: 274
Issued Claim 1 

1 [pre]. A method for controlling a media 

session having at least two transactions 

compnsmg: 

U.S. Patent No. 774907155 

Identification 

T-Mobile Defendants operate an IP Multimedia Subsystem (IMS) 

To the extent the preamble is limiting, IMS mobile origination, for example, practices a method 

for controlling a media session having at least two transactions: 

"4.6.1 Proxy-CSCF 

The Proxy-CSCF (P-CSCF) is the first contact point within the IM CN subsystem. Its address is 

discovered by UEs using the mechanism described in the clause "Procedures related to Local 

CSCF Discove1y". The P-CSCF behaves like a Proxy (as defmed in IETF RFC 3261 [12] or 

subsequent versions), i.e. it accepts requests and services them internally or forwards them on. 

The P-CSCF shall not modify the Request URI in the SIP INVITE message. The P-CSCF may 

behave as a User Agent (as defmed in the IETF RFC 3261 [12] or subsequent versions), i.e. in 

abnonnal conditions it may terminate and independently generate SIP transactions." 

3GPP TS 23.228 V18.0.0 (2022-1 2) p. 49. 

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Page 2 

5.6.2 (M0#2) Mobile origination, home 

This origination procedure applies to users located in their home service area. 

The UE is located in the home network, and determines the P-CSCF via the CSCF discovery procedure described in 

clause 5.1.1. During registration, the home network allocates an S-CSCF in the home network. 

When registration is complete, P-CSCF knows the name/address of S-CSCF. 

Originating Home Network Terminating 

Network 

UE P-CSCF S-CSCF 

1. Invite Initial SOP • tier) 

esource 

Reservation 

1-----

l 

_ ~~rt User 

30. Start Media 

31 . ACK 

2. Invite Initial SOP 

14. Conf Ack O t SD 

32. ACK 

Initial S P Offer) 

. Offer Res nse 

12. Response Co f (Opt SOP) 13. Conf Ack O I SOP) 18. Reservation onf 19. Reservation Conf 

. 2. Ring1ng __ _ 

6. 200 OK 

33. ACK 

Figure 5.15: Mobile origination procedure - home 

Case 2:23-cv-00444-JRG Document 1-20 Filed 09/27/23 Page 3 of 12 PageID #: 
Issued Claim 1 Identification 

"Procedure M0#2 is as follows: 

1. UE#l sends the SIP INVITE request, containing an initial SDP, to the P-CSCF detennined 

via the CSCF discove1y mechanism. The initial SDP may represent one or more media for a 

multi-media session. 

2. P-CSCF remembers (from the registration procedure) the next hop CSCF for this UE. In this 

case it fo1wards the INVITE to the S-CSCF in the home network. 

P-CSCF detennines whether the INVITE message requires priority handling based on user 

profile stored during the registration procedure and/or the priority requested by the user and/or 

MPS code/identifier included in the INVITE message. If the session is detennined to require 

priority handling, then P-CSCF inse1is/replaces the priority indication and fo1wards the INVITE 

to the S-CSCF. 

3. S-CSCF validates the service profile, if a GRUU is received as the contact, ensures that the 

Public User Identity of the served user in the request and the Public User Identity associated 

with the GRUU belong to the same service profile, and invokes any origination service logic 

required for this user. This includes authorization of the requested SDP based on the user's 

subscription for multi-media services. If the Request URI contains the SIP representation of an 

E.164 address then the procedure specified in clause 4.3.5.3 applies. 

4. S-CSCF fo1wards the request, as specified by the S-S procedures. When the INVITE message 

includes priority indication, the S-CSCF fo1wards the INVITE, including the Service User's 

priority level if available. 

5. The media stream capabilities of the destination are returned along the signalling path, per the 

S-S procedures. 

6. S-CSCF fo1wards the Offer Response message to P-CSCF. 

7. P-CSCF instructs the PCRF/PCF to authorize the resources necessaiy for this session. 

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Issued Claim 1 Identification 

8. P-CSCF fo1wards the Offer Response message to the originating endpoint. 

9. UE decides the offered set of media streams for this session, confinns receipt of the Offer 

Response and sends the Response Confnmation to P-CSCF. The Response Confmnation may 

also contain SDP. This may be the same SDP as in the Offer Response received in Step 8 or a 

subset. If new media are defined by this SDP, a new authorization ( as in Step 7) will be done 

following Step 14. The originating UE is free to continue to offer new media on this operation 

or on subsequent exchanges using the Update method. Each offer/answer exchange will cause 

the P-CSCF to repeat the Step 7 again. 

10. Depending on the bearer establishment mode selected for the IP-CAN session, resource 

reservation shall be initiated either by the UE or by the IP-CAN itself. The UE initiates resource 

reservation procedures for the offered media as shown in Figure 5 .15. Othe1wise, the IP-CAN 

initiates the reservation ofrequired resources after step 7. 

11. P-CSCF fo1wards this message to S-CSCF. 

12. S-CSCF fo1wards this message to the te1minating endpoint, as per the S-S procedure. 

13-14. The te1minating end point responds to the originating end with an acknowledgement. If 

Optional SDP is 

contained in the Response Confnmation, the Confnmation Acknowledge will also contain an 

SDP response. If the SDP has changed, the PCSCF authorizes the media. 

15. PCS CF fo1wards the answered media towards the UE. 

16-18. When the resource reservation is completed, UE sends the successful Resource 

Reservation message to the tenninating endpoint, via the signalling path established by the 

INVITE message. The message is sent first to P-CSCF. 

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Issued Claim 1 

[ 1 a] receiving a first message from an 

end user device at an application server 

to initiate a media session; 

Identification 

19-21. The terminating end point responds to the originating end when successful resource 

reservation has occmTed. 

If the SDP has changed, the P-CSCF again authorizes that the resources are allowed to be used. 

22-24. The destination UE may optionally perfo1m ale1i ing. If so, it signals this to the 

originating paiiy by a 

provisional response indicating Ringing. This message is sent to S-CSCF per the S-S procedure. 

It is sent from there toward the originating end along the signalling path. 

25. UE indicates to the originating user that the destination is ringing. 

26-27. When the destination paiiy answers, the tenninating endpoint sends a SIP 200-OK final 

response along the signalling path to the originating end, as specified by the te1mination 

procedures and the S-S procedures, to S-CSCF. 

28. P-CSCF indicates that the media flows authorized for this session should now be enabled. 

29. P-CSCF passes the 200-OK response back to UE. 

30. UE staiis the media flow(s) for this session. 

31-33. UE responds to the 200 OK with an ACK message which is sent to P-CSCF and passed 

along the signalling path to the te1minating end." 

3GPP TS 23.228 V18.0.0 (2022-12) oo. 120-1 22. 

Receiving a first message from an end user device at an application server to initiate a media 

session takes place, for example, in steps 1-3: 

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Issued Claim 1 

f 1 bl fo1warding the first message from 

the application server to a media server; 

Identification 

" I. UE#l sends the SIP INVITE request, containing an initial SDP, to the P-CSCF dete1mined 

via the CSCF discove1y mechanism. The initial SDP may represent one or more media for a 

multi-media session. 

2. P-CSCF remembers (from the registration procedure) the next hop CSCF for this UE. In this 

case it fo1wards the INVITE to the S-CSCF in the home network. 

3. S-CSCF validates the service profile, if a GRUU is received as the contact, ensures that the 

Public User Identity of the served user in the request and the Public User Identity associated 

with the GRUU belong to the same service profile, aud invokes auy origination service logic 

required for this user. This includes authorization of the requested SDP based on the user's 

subscription for multi-media services. If the Request URI contains the SIP representation of au 

E. 164 address then the procedure specified in clause 4.3.5.3 applies." 

The first message is, for example, the "INVITE message" as defined by the standard. 

Fo1warding the first message from the application server to a media server takes place, for 

example, in step 4: 

"4. S-CSCF fo1wards the request, as specified by the S-S procedures. When the INVITE 

message includes priority indication, the S-CSCF fo1wards the INVITE, including the Service 

User's priority level if available." 

"4.2.4 IP multimedia Subsystem Service Control Interface (ISC) 

The ISC interface is between the Serving CSCF and the service platfonn(s). 

An Application Server (AS) offering value added IM se1vices resides either in the user's home 

network or in a third party location. The third party could be a network or simply a stand-alone 

AS. 

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Issued Claim 1 Identification 

The Serving-CSCF to AS interface is used to provide services residing in an AS. Two cases 

were identified: 

- Serving-CSCF to an AS in Home Network. 

- Serving-CSCF to an AS in External Network (e.g., Third Party or Visited) 

The SIP Application Seiv er may host and execute seiv ices. The SIP Application Seiv er can 

influence and impact the SIP session on behalf of the seiv ices and it uses the ISC interface to 

communicate with the S-CSCF. The S-CSCF shall be able to supply the AS with infoimation to 

allow it to execute multiple seiv ices in order within a single SIP transaction. 

The ISC interface shall be able suppoii subscription to event notifications between the 

Application Seiver and S-CSCF to allow the Application Seiver to be notified of the implicit 

registered Public User Identities, registration state and UE capabilities and characteristics in 

tenns of SIP User Agent capabilities and characteristics. 

The S-CSCF shall decide whether an Application Seiv er is required to receive infoimation 

related to an incoming initial SIP request to ensme appropriate seiv ice handling. The decision at 

the S-CSCF is based on (filter) infoimation received from the HSS. This filter infonnation is 

stored and conveyed on a per Application Seiver basis for each user. It shall be possible to 

include a seivice indication in the filter infoimation, which is used to identify seivices and the 

order that they are executed on an Application Seiver within a single SIP transaction. The 

name(s)/address(es) infoimation of the Application Seiver (s) are received from the HSS." 

3GPP TS 23.228 V18.0.0 (2022-12) p. 31. 

"The purpose of optimal media routing (OMR) is to identify and remove unnecessaiy media 

functions from the media path for each media stream associated with a session .... 

The OMR procedures have the following additional characteristics: 

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Issued Claim 1 

[le] establishing the media session 

between the end user device and the 

media server; 

[Id] initiating a first media transaction 

between the media server and the end 

user device via the application server 

using the media session; 

Identification 

- They build on the ALG NAT traversal model that is an alternative to the ICE NAT trnversal 

model. 

- They usually complete within a single end-to-end SDP offer/answer trnnsaction. Some 

transcoding scenarios require additional signalling to complete optimisation. 

- They apply independently to each media sti·eam established by an SDP offer/answer 

ti·ansaction. 

- They apply to media sti·eams established between any types of endpoints ( e.g., UEs, media 

servers, media gateways)." 

3GPP TS 23.228 V18.0.0 (2022-1 2) p. 280. 

Establishing the media session between the end user device and the media server takes place, for 

example, in steps 1-4 (see [la] and [lb]). 

Initiating a first media ti·ansaction between the media server and the end user device via the 

application server using the media session takes place, for example, in steps 5-8: 

"5. The media stream capabilities of the destination are returned along the signalling path, per 

the S-S procedures. 

6. S-CSCF fo1wards the Offer Response message to P-CSCF. 

7. P-CSCF instrncts the PCRF/PCF to authorize the resources necessaiy for this session. 

8. P-CSCF fo1wai·ds the Offer Response message to the originating endpoint." 

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Issued Claim 1 

[ 1 e] conducting the first media 

transaction between the media server and 

the end user device via the application 

server using the media session, the first 

media transaction being conducted by 

transmitting a first media stream from the 

media server to the end user device via 

the application server and transmitting a 

second media stream from the end user 

device to the media server via the 

application server in response to the first 

media stream; 

f 1 fl completing the first media 

transaction between the media server and 

the end user device via the application 

server using the media session; 

[lg] receiving a second message from the 

media server at the application server, the 

second message indicating that the first 

media transaction is complete; 

[lh] transmitting a third message from 

the application server to the media server 

to initiate a second media transaction 

between the media server and the end 

user device via the application server 

Identification 

Conducting the first media transaction between the media server and the end user device via the 

application server using the media session, the first media transaction being conducted by 

transmitting a first media stream from the media server to the end user device via the application 

server takes place, for example, in steps 5-8 (see [Id]). 

And transmitting a second media stream from the end user device to the media server via the 

application server in response to the first media stream takes place, for example, in step 9. 

"9. UE decides the offered set of media streams for this session, confams receipt of the Offer 

Response and sends the Response Confamation to P-CSCF. The Response Confnmation may 

also contain SDP. This may be the same SDP as in the Offer Response received in Step 8 or a 

subset. If new media are defined by this SDP, a new authorization (as in Step 7) will be done 

following Step 14. The originating UE is free to continue to offer new media on this operation 

or on subsequent exchanges using the Update method. Each offer/answer exchange will cause 

the P-CSCF to repeat the Step 7 again." 

Completing the first media transaction between the media server and the end user device via the 

application server using the media session takes place, for example, in steps 1-9 (see [le]). 

Receiving a second message from the media server at the application server, the second message 

indicating that the first media transaction is complete takes place, for example, in steps 5-8: 

The second message is, for example, the "Off er Response message" as defined by the standard. 

Transmitting a third message from the application server to the media server to initiate a second 

media transaction between the media server and the end user device via the application server 

using the same media session used for the first media transaction takes place, for example, in 

steps 10-12: 

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Issued Claim 1 

using the same media session used for 

the first media transaction; 

[Ii] conducting the second media 

transaction between the media server and 

the end user device vi.a the application 

server using the same media session used 

for the first media transaction, the second 

media transaction being conducted by 

transmitting a third media stream from 

the media server to the end user device 

vi.a the application server and 

transmitting a fourth media stream from 

the end user device to the media server 

vi.a the application server in response to 

the third media stream; 

Identification 

" 10. Depending on the bearer establishment mode selected for the IP-CAN session, resource 

reservation shall be initiated either by the UE or by the IP-CAN itself. The UE initiates resource 

reservation procedures for the offered media as shown in Figure 5 .1 5. Othe1w ise, the IP-CAN 

initiates the reservation of required resources after step 7. 

11. P-CSCF fo1wards this message to S-CSCF. 

12. S-CSCF fo1wards this message to the te1minating endpoint, as per the S-S procedure. " 

The third message is, for example, the "Resource Reservation message" as defined by the 

standard. 

Conducting the second media transaction between the media server and the end user device vi.a 

the application server using the same media session used for the first media transaction, the 

second media transaction being conducted by transmitting a third media stream from the media 

server to the end user device vi.a the application server takes places in steps 13-15: 

" 13-14. The te1minating end point responds to the originating end with an acknowledgement. If 

Optional SDP is 

contained in the Response Confomation, the Confomation Acknowledge will also contain an 

SDP response. If the SDP has changed, the PCSCF authorizes the media. 

15. PCS CF fo1wards the answered media towards the UE. " 

And transmitting a fourth media stream from the end user device to the media server via the 

application server in response to the third media stream takes place in steps 16-18: 

" 16-18. When the resource rese1vation is completed, UE sends the successful Resource 

Rese1v ation message to the te1minating endpoint, via the signalling path established by the 

INVITE message. The message is sent first to P-CSCF." 

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Issued Claim 1 

[lj] completing the second media 

transaction between the media server and 

the end user device via the application 

server using the same media session used 

for the first media transaction; and 

flkl receiving a fourth message from the 

media se1ver at the application se1ver, the 

fourth message indicating that the second 

media transaction is complete. 

Identification 

Completing the second media transaction between the media server and the end user device via 

the application server using the same media session used for the first media transaction takes 

place, for example, in steps 16-18: 

" 16-18 When the resource rese1vation is completed, UE sends the successful Resource 

Rese1v ation message to the te1minating endpoint, via the signalling path established by the 

INVITE message. The message is sent first to P-CSCF." 

Receiving a fourth message from the media se1ver at the application se1ver, the fomih message 

indicating that the second media transaction is complete takes place, for example, in steps 19-

21: 

" 19-21. The te1minating end point responds to the originating end when successful resource 

rese1v ation has occmTed. 

If the SDP has changed, the P-CSCF again authorizes that the resources are allowed to be used." 

The fomih message is, for example, the "Rese1vation Conf ' message in step 19 as defined by 

the standard. 

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