ESW – May 2010

UK Architecture for VoIP 999/112s

John Medland – BT 999/112 Policy Manager

UK Emergency Service

BT or CW Public Network

Fixed/MobileNetworks

Stage 1 PSAPs

BT (5) or C&W (2)

Public networks

Police 52%

Ambulance42%

Fire 6%

Coastguard <1%

999/112/ 18000

999/112/18000

(204 Local Controls) (

Public Emergency numbers

- 999/112,

- 18000 (ITU v21 text over voice, ie real time text using special terminals)

•31 million calls each year to stage 1 PSAPs, 55% from mobile phones

•Around 60% are connected to Stage 2 PSAPs (usually within 10 seconds)

Location for emergency callers

• Available automatically on fixed and mobile calls at Stage 1 and Stage 2 PSAPs

• Fixed lines : civic locations as name and address updated daily to Stage 1 PSAP database

• Mobile networks provide cell coverage area (enhanced with timing advance for some) over standard ETSI interface: radius ~2.2km

• Limitations for VoIP calls, calls from private networks, mobile roamers

• Stage 1 PSAPs provide Location Servers which can be accessed by Stage 2 PSAPs ( location retrieved instantly using telephone number + secure TCP/IP link)

• Industry funded Stage 1 PSAPs supply location free to Stage 2 PSAPs (Stage 2 PSAPs pay for their lines, hardware and software)

• Telematics emergency calls (non-standard eCalls) growing and can provide GPS information

Handling VoIP 999 now• PSAPs still TDM based so VoIP goes through PSTN / IP

Gateways• Small number of VoIP 999s at present, mostly fixed users• Regulation says if PSTN access, then must allow 999 • 999s identified as VoIP• Registered “default” address accessed through E164 tel

number (CLI) for “fixed” users….• ….but default address marked as needing voice

confirmationVerbal routing

• Device/CPE use PSTN/GSM for 999 if possible

• Key issues for VoIP 999 : -- only default name+address data from large number of VoIP SPs- challenge of 24 hour VSP contact point for PSAP use (tracing, alternative contact numbers)- lack of information to PSAP for nomadic users

• Need to Automate Location provision………

NICC Task Group• The Network Interoperabilty Consultative Committee : NICC is a

UK telecommunications industry committee which acts as an industry consensus group in which specifications and technical issues associated with network competition can be discussed. It also is a source of technical advice to the UK Regulator

• Location Task Group : Routing 999/112 for VoIP to correct local EA supplying caller location information on all calls

• Membership : BT, C&W, Ericssons, Huawei, Andrew, Nominet, Magrathea, Aeonvista,Vodafone, VirginMedia, Orange, and Ofcom +….

• Approach :-

- VSP, ISP and Access Provider(s) all different organisations- PSAPs are still TDM based- Start with UK only (all parties UK-based) - Cover DSL, Cable, Enterprise, WiFi and GSM scenarios - Use developing standards wherever possible, eg IETF, ETSI- Don’t rely on user- Don’t rely on device

Key

VPC

VoIP call

CLI + VSP1 id

VSP 1Soft-Switch

Emergency Handling Authority –Stage 1 PSAP

Internet service & access infrastructure providers

PIGPIG

CLI + VSP1 id

IAIC

Request using CLI, VSP id.Response gives location

1

c

3

4

b

ISP LIS

SBC2

PSTN—IP Gateway

VSP 2 soft switch (Aggregation + SS7 interconnect )

a

SBC1

SBC1/2

Source IP+Port, VSP 1 ID and CLI information (NENA v2)

Access and IP Log-on functions

2

Voice path

Data path

Overview of Architecture and Interfaces

HELD third party request using Source IP (+ Port no.), in HELD ID extensions. Response gives PIDF-LO

LIS URI IP

VoIP Positioning Centre

VSP Soft Switch

Emergency Handling Agency

ISP LIS

IAIC (IP Address to ISP Converter)

Interface (a)Key Parameters (CLI,

Source Public IP Address, source port number)

Interface ( b)Parameter (Source Public IP Address)

Inteface(b)Parameter (ISP LIS

URI)

Interface ( c )Parameter (Source Public IP Address)

Interface (4)Parameter

(CLI)Interface (4)Parameter(Location)

Interface( c )Parameter (PIDF-LO

Location)

VPC Functions

IAIC

AS / LIS mapping

IP / AS mapping

IP Address

LIS URI

BGP4 Route Collector

BGP Route Updates

Interface (b)

BGP Peers

VPC - Mapping Source IP address to ISP

LIS

HELD Server

IP@ translation; Border Functions - NAPT/SBC/ALG

OSS Systems

Network

elements

Interface (c)

iL2

iM1

iC1

iB1LIS

Other LIS

Generic LIS Functions

Broadband and ADSL Access

IP N/W

Voice

Term

ina

l

Management

Control

Media

Resid

ential

G/W

RADIUSServer

RADIUSServer

LIS VPC

OSSISPOSSBAPOSSLLP

(RADIUS)

(RADIUS)

(RADIUS)

L2T

P A

ccessC

oncen

trator

L2T

P N

etwork

Server

(RADIUS)

DS

LA

M

SIP

RTP/RTCP

Figure E1: xDSL Architecture for PPP Tunnelled via L2TP to ISP

UserEnvironment

Local LoopProvider

Backhaul &Aggregation

Provider

Internet ServiceProvider

EmergencyHandlingCentre

InternetTelephony

ServiceProvider

BB Service Req (Billing Adrs, Inst Adrs)

BB Service Req (RefISP,MPF,Inst Adrs)

BB Service Req (RefBAP, MPF, Inst Adrs)

BB Service Resp (RefBAP,SIDLLP)

LIS Add Info (SIDBAP, Inst Adrs)

BB Inst Adrs Audit Req(List[SIDBAP])

BB Inst Adrs Audit Req(List[SIDLLP])

BB Inst Adrs Audit Resp(List[SIDLLP,Inst Adrs])

BB Inst Adrs Audit Resp(List[SIDLLP,Inst Adrs])

LIS Add/Remove/Modify Info(SIDBAP, Inst Adrs)

OSSISPOSSBAPOSSLLP LISBBCustomer

Figure E5: BB Provision and Audit on a MPF Line For Binding of Service Identifier (SID) to Installation Address (Inst Adrs)

BB Service Resp (RefISP,SIDBAP)

Audit

Provision

Resid

ential

G/W LIS

DS

LA

M

L2T

PA

ggregationC

oncen

trator

ISPRADIUSServer

Figure E2: Network Attachment for PPP Tunnelled via L2TP to ISP

L2T

PN

etwork

Server

BAPRADIUSServer

L2TP Tunnel Establishment

PPP Resp (UID,#PW#)

RADIUS Auth Req(UID,Token,#PW#,IA=SIDBAP)

PPP Challenge(Token)PPP Challenge(Token)

PPP Response(UID,#PW#, IA=SIDBAP)

RADIUS Auth Req(UID,Token,#PW#,IA=SIDBAP)

Auth Accept

RADIUS Accounting Req

(IP Adrs,SIDBAP)

PPP Link Est ReqPPP Link Est Req

PPP Link Est RespPPP Link Est Resp

PPP IPCP Config Req (IP Adrs)

PPP IPCP Config Resp

RADIUS Accounting Req(IP Adrs,SIDBAP)

RADIUS Accounting Resp

Auth Accept(L2TP Tunnel End Pt, Tunnel Id)

L2TP Tunnel Est Req(Tunnel Id,UID,Token,#PW#)

L2TP Tunnel Est Resp

RADIUS Accounting RespNB This example shows the case of an Intermediate Agent at the DSLAM signalling the SIDBAP and the ISP’s LNS allocating IP Addresses.

Way Forward for UK

• NICC Standard published Jan 2010 http://www.niccstandards.org.uk/files/current/ND1638%20V1.1.2.pdf?type=pdf

• New requirements on all organisations (systems development)

• Many more organisations involved to deliver 999 (not just traditional telcos but VSPs and ISPs)

• New operational components : LIS and VPC

• New interfaces for all organisations: based on international standards as far as possible (eg IETF HELD)

• Increased co-op and trust relationships between PSAP and VSP, ISP and Access networks

• NICC Work to continue : other use cases, IP PSAPs (IP end to end)