1. Emergency Text Messaging using SIP MESSAGE draft-kim-ecrit-text-00
Jong Yul Kim
Wonsang Song
Henning Schulzrinne
Pietr Boni
Michael Armstrong
IPR disclosure:
IETF 77

2. Introduction How to use page-mode messaging for emergency?
Using SIP MESSAGE for session-less IM and SMS
For the endpoints that do not support session-based text (e.g., Real-time text, MSRP)
Draft contains:
Overview of operation
UAC behavior
Proxy behavior
Conversion to SIP MESSAGE
IETF 77

3. Overview of operation . . . … IM Network SMS Network Resolve ESRP
Create soft state for each IM caller
Static routing after the first LoST query
PSAP SIP Proxy
ACD
Call Takers
Conference Server
Emergency Services IP Network (ESInet)
Emergency Services Routing Proxy (ESRP)
Location-to-Service Translation (LoST) Server
IP PSAP A …
. . .
IP PSAP Z
Create soft state for each text caller
Static routing after the first LoST query
IM Network
IM Client
SIP Proxy
Resolve ESRP
LoST Server
SMS Network
- Create record for each text caller
- Static routing after first call taker assignment
Cellular phone
SMS-SIP Gateway
Create soft state for each SMS caller
Static routing after the first LoST query
IETF 77

4. UAC behavior Basically, follows rules from both:
MESSAGE urn:service:sos SIP/2.0
To: urn:service:sos
From:
Route:
Geolocation:
Content-Type: multipart-mixed; boundary=”--- =_RjhENkI3RjQ”
----- =_RjhENkI3RjQ
MIME-Version: 1.0
Content-ID:
Content-Type: text/plain
Content-Transfer-Encoding: 8bit
Hello, I need help.
Content-ID:
Content-Type: application/pidf+xml
Content-Transfer-Encoding: UTF-8
<PIFO-LO omitted>
Basically, follows rules from both:
SIP MESSAGE (RFC 3428)
Framework for Emergency Calling using Internet Multimedia (draft-ietf-ecrit- framework-10)
Also, sends MESSAGE consistently to the same ESRP or the same outbound proxy during conversation.
Next hop is fixed after first MESSAGE is sent.
IETF 77

5. Proxy behavior Stores a record to track MESSAGE requests.
(Source SIP URI, next hop, expiration timer)
Routes all subsequent MESSAGE requests from the same source to the same next hop.
Resets expiration timer when receiving subsequent MESSAGE.
Deletes record if timer expires.
Above only applies to proxies that route MESSSAGE based on policy or location. (e.g. ESRP)
From header field
of MESSAGE
Record valid time
in seconds
Either ESRP or PSAP URL
from first LoST query
IETF 77

6. Conversion to SIP MESSAGE
SMS-SIP/IM-SIP gateway converts SMS/IM messages to SIP MESSAGE requests.
Type of information
Where to place in SIP MESSAGE
Origination address or number
From header field
Destination address or number*
(if not urn:service:sos)
History-Info header field
User message
Body
Location information
Geolocation header field and body
* To header and request URI should be urn:service:sos.
IETF 77

7. Related issue: location in SMS
(Not part of this draft, but needs to be solved)
Location delivery:
out of band: there is (generally) no p-ANI
also fails for international visitors, among others
in-band: add information to SMS
160 limit  compression
IETF 77