> ## Documentation Index
> Fetch the complete documentation index at: https://docs.telegent.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Elastic SIP Trunk Documentation
> Use-case samples, PCAP snippets, and a reference guide for SIP INVITEs and expected header-handling behavior when interworking T-Mobile, Joonto SBC/OpenSIPS, and UC partners.
## Overview
The following provides specific use-case samples and examples of various SIP documentation, PCAP snippets, and reference guide for SIP INVITEs and expected header-handling behavior when interworking T-Mobile, Joonto SBC/OpenSIPS, and UC partners.
Telegent highly recommends sending the `Identity` header received from T-Mobile whenever possible. If an upstream partner does not provide the `Identity` header, the call should still be allowed to proceed, but may have potential for STIR/SHAKEN attestation issues.
***
## Voice Origination – OTT
* The `Diversion` header allows an OTT call to not automatically be marked as scam likely on the T-Mobile network, because the call didn't originate on the device
* `PRACK` is required for T-Mobile to ring the device
### Inbound INVITE sample where no Identity header is passed to Telegent SBC
```text theme={null}
INVITE sip:+19087645402@13.83.167.165:5060 SIP/2.0
Via: SIP/2.0/UDP 137.192.80.69:5060;branch=z9hG4bKa3b9hn207o8hmq36oqj0.1
Max-Forwards: 69
From: ;tag=06gN621vNF84F
To:
Call-ID: d42edea3-7661-123f-989f-be10809469ca
CSeq: 110219115 INVITE
Contact:
User-Agent: vp2-inteliquent
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, REGISTER, REFER, NOTIFY
Supported: timer, path, replaces
Allow-Events: talk, hold, conference, refer
Content-Type: application/sdp
Content-Disposition: session
Content-Length: 394
Remote-Party-ID: "+17328532203" ;party=calling;screen=yes;privacy=off
P-Asserted-Identity:
Diversion: ;reason=deflection
```
***
## Voice Termination – Single SIM Device Endpoint
### Step 1: Inbound INVITE sent first to UC partner for inbound ringing with Identity header
```text theme={null}
INVITE sip:+14155837080@3.232.127.185 SIP/2.0
Via: SIP/2.0/UDP 13.83.167.160:5060;branch=z9hG4bKeade.3d49cb14.0
Max-Forwards: 62
From: ;tag=as1eb30ca5
To:
Call-ID: 511cb1aa5180c4b84a1ab34e06988c55@12.7.192.27
CSeq: 102 INVITE
Contact:
Supported: replaces
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,SUBSCRIBE,NOTIFY,INFO,PUBLISH,MESSAGE
P-Asserted-Identity: tel:+15302899128
Content-Type: application/sdp
Content-Length: 318
Session-Expires: 1800;refresher=uas
Identity: eyJhbGciOiJFUzI1NiIsInBwdCI6InNoYWtlbiIsInR5cCI6InBhc3Nwb3J0IiwieDV1IjoiaHR0cHM6Ly9zdGlyLm5hNC5saXZldm94LmNvbS9jZXJ0L1I5ZmZsdGZMIn0.eyJhdHRlc3QiOiJBIiwiZGVzdCI6eyJ0biI6WyIxNDE1NTgzNzA4MCJdfSwiaWF0IjoxNzY5NTM2NTAxLCJvcmlnIjp7InRuIjoiMTUzMDI4OTkxMjgifSwib3JpZ2lkIjoiNGQxOGM4ODQtZmJhOS0xMWYwLWI1ZDEtMWJlMGJiM2QzMDkyIn0.yY88EdiWSNEig4loaAUqF6eqh0Z2J_H42AaIbtnhcwcvf7wGGi48DNG10QhCz-pSYkJbh5nQY9gLHd_hQ3llgQ;info=;alg=ES256;ppt="shaken"
v=0
o=ccs-0-303-11 0300111855943011 1470322392 IN IP4 13.83.167.160
s=CX-IVS-SBC
c=IN IP4 13.83.167.160
b=AS:80
b=RS:1000
b=RR:3000
t=0 0
m=audio 31562 RTP/AVP 0 101
b=AS:80
b=RS:1000
b=RR:3000
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=sendrecv
a=rtcp:31563
a=ptime:20
```
### Step 2: INVITE sent to Telegent SBC for ringing SIM device
* `PRACK` is required for T-Mobile to ring the device
```text theme={null}
INVITE sip:+14155837080@13.83.167.160:5060 SIP/2.0
Via: SIP/2.0/UDP 3.232.127.185:5060;rport;branch=z9hG4bKPjd861bc21-52a2-41fc-8f03-db9b6f353727
From: ;tag=e7ffee04-82a3-421b-93ba-c6c0701eb71d
To:
Contact:
Call-ID: 427dd7b3-49bd-45b2-8525-e3030f3d0463
CSeq: 15418 INVITE
Allow: OPTIONS, REGISTER, SUBSCRIBE, NOTIFY, PUBLISH, INVITE, ACK, BYE, CANCEL, UPDATE, PRACK, MESSAGE, REFER
Supported: 100rel, timer, replaces, norefersub, histinfo
Session-Expires: 1800
Min-SE: 90
P-Asserted-Identity:
Identity: eyJhbGciOiJFUzI1NiIsInBwdCI6InNoYWtlbiIsInR5cCI6InBhc3Nwb3J0IiwieDV1IjoiaHR0cHM6Ly9zdGlyLm5hNC5saXZldm94LmNvbS9jZXJ0L1I5ZmZsdGZMIn0.eyJhdHRlc3QiOiJBIiwiZGVzdCI6eyJ0biI6WyIxNDE1NTgzNzA4MCJdfSwiaWF0IjoxNzY5NTM2NTAxLCJvcmlnIjp7InRuIjoiMTUzMDI4OTkxMjgifSwib3JpZ2lkIjoiNGQxOGM4ODQtZmJhOS0xMWYwLWI1ZDEtMWJlMGJiM2QzMDkyIn0.yY88EdiWSNEig4loaAUqF6eqh0Z2J_H42AaIbtnhcwcvf7wGGi48DNG10QhCz-pSYkJbh5nQY9gLHd_hQ3llgQ;info=;alg=ES256;ppt=shaken
Max-Forwards: 70
User-Agent: Asterisk PBX 18.10.0~dfsg+~cs6.10.40431411-2
Content-Type: application/sdp
Content-Length: 263
v=0
o=- 1032313863 1032313863 IN IP4 3.232.127.185
s=Asterisk
c=IN IP4 3.232.127.185
t=0 0
m=audio 17256 RTP/AVP 0 8 101
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:20
a=maxptime:150
a=sendrecv
```
### Sample of above call scenario
***
## Voice Termination – Forked Device Example
### Step 1: Inbound INVITE sent first to UC partner for inbound ringing with Identity header
```text theme={null}
INVITE sip:+13852213180@104.42.190.204 SIP/2.0
Via: SIP/2.0/UDP 13.83.167.160:5060;branch=z9hG4bK1a78.87ff9873.0
Max-Forwards: 64
From: ;tag=mavodi-__stsxvrswsxw__0-80-ad-7-0-70003-0-0-0-1766076149-_155985-bb2ec
To:
Call-ID: 0A58AC142435-cb5-dd85f700-aca53b-69442ef5-bb1ab
CSeq: 1 INVITE
Contact:
P-Early-Media: supported
Supported: path,replaces,100rel
Allow: ACK,BYE,CANCEL,INFO,INVITE,MESSAGE,NOTIFY,OPTIONS,PRACK,REFER,UPDATE
P-Asserted-Identity:
Content-Type: application/sdp
Content-Length: 268
Session-Expires: 1800;refresher=uas
Identity: eyJhbGciOi... [truncated]
```
### Step 2: INVITE forked to alternate branch (e.g. SIM/OTT app)
```text theme={null}
INVITE sip:+13852213180@13.83.167.164 SIP/2.0
Via: SIP/2.0/UDP 13.83.167.160:5060;branch=z9hG4bK1a78.87ff9873.1
Max-Forwards: 64
From: ;tag=mavodi-__stsxvrswsxw__0-80-ad-7-0-70003-0-0-0-1766076149-_155985-bb2ec
To:
Call-ID: 0A58AC142435-cb5-dd85f700-aca53b-69442ef5-bb1ab
CSeq: 1 INVITE
Contact:
P-Early-Media: supported
Supported: path,replaces,100rel
Allow: ACK,BYE,CANCEL,INFO,INVITE,MESSAGE,NOTIFY,OPTIONS,PRACK,REFER,UPDATE
P-Asserted-Identity:
Content-Type: application/sdp
Content-Length: 268
Session-Expires: 1800;refresher=uas
Identity: eyJhbGciOi... [truncated]
```
If the OTT branch answers first, Telegent sends `CANCEL` to the other forked INVITE branch. This stops ringing on the remaining destination and behaves like standard simultaneous ringing.
***
## Voice Termination – Body Example
### Body samples
```text theme={null}
Message Body
Session Description Protocol
Session Description Protocol Version (v): 0
Owner/Creator, Session Id (o): ccs-0-303-3 030031921555243 768119725 IN IP4 13.83.167.165
Owner Username: ccs-0-303-3
Session ID: 030031921555243
Session Version: 768119725
Owner Network Type: IN
Owner Address Type: IP4
Owner Address: 13.83.167.165
Session Name (s): -
Connection Information (c): IN IP4 13.83.167.165
Connection Network Type: IN
Connection Address Type: IP4
Connection Address: 13.83.167.165
Time Description, active time (t): 0 0
Session Start Time: 0
Session Stop Time: 0
Media Description, name and address (m): audio 35508 RTP/AVP 0 100
Media Type: audio
Media Port: 35508
Media Protocol: RTP/AVP
Media Format: ITU-T G.711 PCMU
Media Format: DynamicRTP-Type-100
Bandwidth Information (b): AS:88
Bandwidth Modifier: AS [Application Specific (RTP session bandwidth)]
Bandwidth Value: 88 kb/s
Media Attribute (a): maxptime:40
Media Attribute Fieldname: maxptime
Media Attribute Value: 40
Media Attribute (a): rtpmap:0 PCMU/8000
Media Attribute Fieldname: rtpmap
Media Format: 0
MIME Type: PCMU
Sample Rate: 8000
Media Attribute (a): rtpmap:100 telephone-event/8000
Media Attribute Fieldname: rtpmap
Media Format: 100
MIME Type: telephone-event
Sample Rate: 8000
Media Attribute (a): fmtp:100 0-15
Media Attribute Fieldname: fmtp
Media Format: 100 [telephone-event]
Media format specific parameters: 0-15
Media Attribute (a): sendrecv
Media Attribute (a): rtcp:35509
Media Attribute Fieldname: rtcp
Media Attribute Value: 35509
Media Attribute (a): ptime:20
Media Attribute Fieldname: ptime
Media Attribute Value: 20
[Generated Call-ID: 0A58AC142435-cb5-dd85f700-aca53b-69442ef5-bb1ab]
```
Need help or have questions? Contact [support@telegent.com](mailto:support@telegent.com)