Emergency call real time text (RTT) to RTT exchange

Inventors: Jenniffer F. Lucas Cruz (Bellevue, WA); Oliver Rankine (Bellevue, WA); Gladys Martinez-Herrera (Monroe, WA); Robert E. Golden (Liverpool, NY)

Assignee: T-Mobile USA, Inc.

H04W4/90 H04W4/12

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Quick Facts

Patent No.: US 12671969
App. No.: 18/331,061
Granted: Jun 30, 2026
Kind: B2

External Links

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Abstract

Emergency calls that use real time text (RTT) in addition to audio face a challenge: between an originating endpoint (e.g., a cellular network) sending a session initiation protocol (SIP) invite and receiving the response (e.g., 200 OK) from a downstream terminating endpoint (e.g., a peering network), the media attribute fields associated with the text and audio data may become swapped. Three options are disclosed for dealing with this issue. (1) The originating endpoint may swap the protocol paths for the RTT and audio data so that the public safety answering point (PSAP) and the user equipment (UE) are able to communicate. (2) The originating endpoint may send a correction request to the terminating endpoint. (3) If default protocol paths are specified for RTT and audio, the originating endpoint uses the default protocol paths independently of whether the SIP invite or response specified the correct data type and protocol path association.

Claims (36)

1 . A method comprising:

transmitting, by an originating endpoint, to a terminating endpoint, an emergency call request, wherein the emergency call request identifies a first protocol and a second protocol, and wherein the emergency call request comprises a first data type associated with a first media attribute field and a second data type associated with a second media attribute field;

receiving a response to the emergency call request, wherein the response comprises the first data type associated with the second media attribute field and the second data type associated with the first media attribute field, wherein determining that the first data type and the second data type have swapped associations comprises determining that a first protocol path value associated with the first data type in the emergency call request is present in the second media attribute field in the response, and that a second protocol path value associated with the second data type in the emergency call request is present in the first media attribute field in the response;

determining that the first data type and the second data type have swapped associations with the first media attribute field and the second media attribute field; and

based on the determination that the first data type and the second data type have swapped associations, transmitting data of the first data type using the second protocol path value of the second media attribute field, and transmitting data of the second data type using the first protocol path value of the first media attribute field.

2 . The method of claim 1 , wherein the first data type comprises a text data type and the second data type comprises an audio data type.

3 . The method of claim 1 , wherein the first data type comprises real time text (RTT).

4 . The method of claim 1 , wherein the first protocol comprises a real time protocol (RTP) and the second protocol comprises an audio video protocol (AVP).

5 . The method of claim 1 , wherein the emergency call request comprises a session initiation protocol (SIP) invite and the response comprises a SIP 200 OK.

6 . The method of claim 1 , wherein the terminating endpoint comprises a public safety answering point (PSAP) node; or the terminating endpoint comprises a node within a peering network between the originating endpoint and a PSAP node.

7 . The method of claim 1 , further comprising:

using header manipulation rules (HMR) to swap the first data type to the second protocol path value of the second media attribute field and to swap the second data type to the first protocol path value of the first media attribute field.

8 . A system comprising:

a processor; and

a computer-readable medium storing instructions that are operative upon execution by the processor to:

transmit, by an originating endpoint, to a terminating endpoint, an emergency call request, wherein the emergency call request identifies a first protocol and a second protocol, and wherein the emergency call request comprises a first data type associated with a first media attribute field and a second data type associated with a second media attribute field;

receive a response to the emergency call request, wherein the response comprises the first data type associated with the second media attribute field and the second data type associated with the first media attribute field;

determine that the first data type and the second data type have swapped associations with the first media attribute field and the second media attribute field, wherein determining that the first data type and the second data type have swapped associations comprises determining that a first protocol path value associated with the first data type in the emergency call request is present in the second media attribute field in the response, and that a second protocol path value associated with the second data type in the emergency call request is present in the first media attribute field in the response; and

based on the determination that the first data type and the second data type have swapped associations, transmit data of the first data type using the second protocol path value of the second media attribute field, and transmit data of the second data type using the first protocol path value of the first media attribute field.

9 . The system of claim 8 , wherein the first data type comprises a text data type and the second data type comprises an audio data type.

10 . The system of claim 8 , wherein the first data type comprises real time text (RTT).

11 . The system of claim 8 , wherein the first protocol comprises a real time protocol (RTP) and the second protocol comprises an audio video protocol (AVP).

12 . The system of claim 8 , wherein the emergency call request comprises a session initiation protocol (SIP) invite and the response comprises a SIP 200 OK.

13 . The system of claim 8 , wherein the terminating endpoint comprises a public safety answering point (PSAP) node; or the terminating endpoint comprises a node within a peering network between the originating endpoint and a PSAP node.

14 . The system of claim 8 , wherein the instructions are further operative to:

use header manipulation rules (HMR) to swap the first data type to the second protocol path value of the second media attribute field and to swap the second data type to the first protocol path value of the first media attribute field.

15 . One or more computer storage devices having computer-executable instructions stored thereon, which, upon execution by a computer, cause the computer to perform operations comprising:

determining that the first data type and the second data type have swapped associations with the first media attribute field and the second media attribute field, wherein determining that the first data type and the second data type have swapped associations comprises determining that a first protocol path value associated with the first data type in the emergency call request is present in the second media attribute field in the response, and that a second protocol path value associated with the second data type in the emergency call request is present in the first media attribute field in the response; and

16 . The one or more computer storage devices of claim 15 , wherein the first data type comprises a text data type and the second data type comprises an audio data type.

17 . The one or more computer storage devices of claim 15 , wherein the first data type comprises real time text (RTT).

18 . The one or more computer storage devices of claim 15 , wherein the first protocol comprises a real time protocol (RTP) and the second protocol comprises an audio video protocol (AVP).

19 . The one or more computer storage devices of claim 15 , wherein the emergency call request comprises a session initiation protocol (SIP) invite and the response comprises a SIP 200 OK.

20 . The one or more computer storage devices of claim 15 , wherein the terminating endpoint comprises a public safety answering point (PSAP) node; or the terminating endpoint comprises a node within a peering network between the originating endpoint and a PSAP node.