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VoIP i2 Architecture Part II

SBC – Southwest Public Safety. VoIP i2 Architecture Part II. 9-1-1 Call Routing. The Interim VoIP Architecture for Enhanced 9-1-1 Services (i2) document was the primary source of information used to create this presentation .

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VoIP i2 Architecture Part II

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  1. SBC – Southwest Public Safety VoIP i2 ArchitecturePart II 9-1-1 Call Routing

  2. The Interim VoIP Architecture for Enhanced 9-1-1 Services (i2)document was the primary source of information used to create this presentation. • This NENA STANDARD is published by National Emergency Number Association (NENA) as a guide for the designers and manufacturers of systems that are used for the purpose of processing emergency calls.

  3. Now here’s a step-by-step look at a 9-1-1VoIP Call Flow Introduction VoIP i29-1-1 Call Routing is Part 2 in the 9-1-1 VoIP series. It is important that you review Part 1: VoIP i2 - IP Domain, prior to viewing this presentation to gain an understanding of the components in the VoIP architecture and the definitions of the acronyms used.

  4. Emergency Services Provider Network Call Server PSAP ESGW E9-1-1 Selective Router 7. Invite(ESRN,ESQK) 8. Call route (ESQK) V4 9. Deliver Call (ESQK) 2. Call Initiation 3. Query (Callback LIE), V1 V2 6. Response (ESRN, ESQK, LRO) User Agent Endpoint 11.ESPOSREQ Query VPC 10. ALI query (ESQK) 5. Response (LO) V0 12. ESPOSREQ Response (CBN, LO) 1. LO and/or LK 13. ALI response 4. Query(LK) LIS (Callback, LO) V3 MSAG ERDB MSAG MSAG VDB DBMS 9-1-1 Call Flow VoIP Domain SRDB 14. ESQK De-allocation

  5. Basic Call Routing of a VoIP Emergency Call GOT IT? Now the next slide also has the IP Call Flow graphically depicted. But on this slide you can click on any of the indicated steps in the call flow for a closer look at that particular step.

  6. Emergency Services Provider Network Call Server PSAP ESGW 7. Invite(ESRN,ESQK) E9-1-1 Selective Router V4 8. Call route (ESQK) 9. Deliver Call (ESQK) 2. Call Initiation 3. Query (Callback LIE), V2 6. Response (ESRN, ESQK, LRO) VPC 10. ALI query (ESQK) 5. Response (LO) 13. ALI response 4. Query(LK) (Callback, LO) V3 ERDB 9-1-1 Call Flow VoIP Domain V1 SRDB 11.ESPOSREQ Query User Agent Endpoint V0 12. ESPOSREQ Response (CBN, LO) 1. LO and/or LK LIS MSAG 14. ESQK De-allocation MSAG MSAG VDB DBMS

  7. LIS Step 1 – LO and/or LK User Agent Endpoint Click on picture to see animation V0 interface LO/LK The LO/LK is downloaded from the Location Information Server (LIS) to the endpoint by the Dynamic Host Configuration Protocol (DHCP) server, using the V0 interface. Click on this button to return to the diagram

  8. Call server Step 2 – Call Initiation User Agent Endpoint V1 interface 9-1-1 + LO The VoIP endpoint originates an emergency call by sending a call initiation request, designating sos@local.domain.name as the target destination, and including Callback information, and the LO using the V1 interface.

  9. Call server Step 3 – Query Routing request VPC V2 interface The Call Server receives the call initiation request and sends a routing request to the VPC using the information received in the call request over the V2 interface.

  10. Step 4 – Query (LK) Step 5 – Response (LO) VPC Location Key V3 interface LIS Location • The VPC queries the identified LIS over the V3 interface, including the received location key. • The LIS returns to the VPC the LO it has associated with the Client-ID.

  11. Call server Step 6 – Response VPC Location (LO) V2 interface ESQK/ESRN, LO ERDB ESQK/ESRN • The VPC uses the LO to obtain the ESZ-related routing information from the ERDB (including the, ESRN, ESN, and CRN) that will enable the routing via the ESGW to the SR that serves this ESZ. • The VPC uses the received routing information to allocate an available ESQK from the pool of ESQKs appropriate for the SR/ESN associated with the caller’s location/ESZ and sends a response to the routing request for this call, including the allocated ESQK and ESRN, as well as the appropriate LRO.

  12. Call ESGW server Step 7 – Invite (ESRN, ESQK) ESQK/ESRN V4 interface • The Call Server will take the ESRN received in the response and use it as the basis for selecting the appropriate ESGW with which to route the emergency call. • The Call Server routes the call to the ESGW, including the ESRN provided by the VPC and the ESQK.

  13. E9-1-1 Selective Router ESGW Step 8 - Call Route 9-1-1 + ESQK CAMA/ SS7 • The ESGW uses the received ESRN to select an outgoing route (i.e., trunk group) to the appropriate E9‑1‑1 SR. • The ESGW signals an emergency call origination to the E9‑1‑1 SR, using outgoing (SS7 or MF) signaling that includes the digits “9-1-1” as the called number and the ESQK as the calling number/ANI.

  14. E9-1-1 S/R ESN PSAP Step 9 – Deliver Call ESQK ESQK SRDB • The SR receives the emergency call, uses the ESQK to query the SRDB for the associated Emergency Service Number (ESN), and uses the ESN to identify the appropriate PSAP for the call. • The SR then delivers the call to the appropriate PSAP, signaling the ESQK as the Automatic Number Identification (ANI) information.

  15. PSAP Step 10 – ALI Query ALI Database ESQK The PSAP ANI/ALI controller receives the call setup signaling, and sends an ALI query to its serving ALI DB, using the ESQK as the query key.

  16. Step 11 - ESPOSREQ ALI Database VPC ESPOSREQ w/ESQK The ALI DB sends an Emergency Services Positioning Request (ESPOSREQ)to the VPC (identified in the shell record for the ESQK in the ALI DB), which includes the ESQK as the query key in the request. For further information on ESPOSREQ, click on the acronym

  17. ESPOSREQ • Emergency Service Position Request from ALI to MPC, is used to request the initial, updated, or last known position of a wireless handset or other device. If the requesting entity is authorized, the VPC shall use the ESQK contained in the Emergency Services Routing Key parameter of the ESPOSREQ message to identify the call instance, and to look up the associated call and location-related information stored at the VPC.

  18. Step 12 - ALI Query ALI Database VPC ESPOSREQ CBN, LOC, VSP • The VPC receives the ESPOSREQ from the ALI DB, and uses the ESQK to retrieve the ALI record information it stored previously (in Step 4). • The VPC returns the ESPOSREQ response to the ALI DB to provide the Callback Number, the Location information, and the VSP provided information that can be supported by the V-E2 interface.

  19. Step 13 - ALI Response ALI Database John Smith xxx-xxx-xxxx 1234 W. 6th Ave Eagle Lake, MO. Fire - xxx xxx -xxxx EMS - xxx-xxx -xxxx Police - xxx- xxx-xxxx ALI Response • The ALI DB receives the ESPOREQ from the VPC (it may also extract additional information from the shell record for the ESQK). • The ALI DB returns an ALI response to the PSAP, following requirements in NENA 02-010.

  20. Step 14 – ESQK De-allocation When the VPC receives an indication that a particular instance of an emergency call is being cleared, the VPC de-allocates the associated ESQK and makes it available for subsequent emergency calls. Note that release of the ESQK may occur as a result of an indication of call release over the V2 interface from the Call Server/Routing Proxy, or the expiration of the ESQK guard timer, whichever occurs first.

  21. Emergency Services Provider Network Call Server PSAP ESGW E9-1-1 Selective Router 7. Invite(ESRN,ESQK) 8. Call route (ESQK) V4 9. Deliver Call (ESQK) 2. Call Initiation 3. Query (Callback LIE), V1 One More Time Altogether! V2 6. Response (ESRN, ESQK, LRO) User Agent Endpoint 11.ESPOSREQ Query VPC 10. ALI query (ESQK) 5. Response (LO) V0 12. ESPOSREQ Response (CBN, LO) 1. LO and/or LK 13. ALI response 4. Query(LK) LIS (Callback, LO) V3 MSAG ERDB MSAG MSAG VDB DBMS 9-1-1 Call Flow VoIP Domain SRDB 14. ESQK De-allocation SBC – Southwest Public Safety Frank Abbenhaus

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