enhanced services for converged networks

© 2003, SS8 Networks, Inc. Proprietary. Do Not Copy or Distribute Without Permission.

Enhanced Services for Converged Networks

The Importance of SS7

Internet Telephony Expo

February 2003

© 2003, SS8 Networks, Inc. Proprietary. Do Not Copy or Distribute Without Permission. 2

Leveraging SS7 for IP Telephony

• Before SS7-IN for IP Voice can be discussed….

• What is IP Telephony?

– Technical Models

– Business Models

– Where it is going

• The Role of SS7 in IP Telephony

– PSTN Interconnect

– Service Delivery (Existing)

– Service Development (New)

• Leveraging SS7

– Do you have a choice?

– Should you have a choice?


What is IP Telephony/VoIP?

• Well, it’s Telephony using IP…..(duh)?• What is new about it?

– Well, it uses IP….(duh)• IP Telephony can mean many things:

– Trunking between class 4 switches (arbitrage and intercarrier)

– Trunking between class 5 switches (tandem apps)– Replacing Class 5 switches (access)– A new thing? A new form of communication?

• IP Telephony is really about three things:– Redefining Access– Redefining Services– Integrating Discrete forms of communications (mobile, voice,

visual, information, dialogue, broadcast, entertainment)


The Business Drivers for IP Voice

• Technology is not the driver

– Subscribers don’t care about protocols, codecs or algorithms.

• Access

– Finding new ways to reach the customer

– Increasing accessibility of services to the customer• Mobility of voice

• Access through multiple devices

• Bypassing ownership of physical plant

• Services

– Enhanced ability to use existing services• Web provisioning

• Voice navigation

• Always on, always there

– Cool new services

• Integrating the four primary communications tools


Evolution of IP Voice

• Current focus is on re-inventing traditional voice services and architectures on an IP backbone

• Incremental improvements and feature enhancements– Integration with PC voice applications like Windows Messenger– Web-based provisioning of service– Mobility

• SS7 is the primary mechanism for controlling call states and services • Longer-term, the Services Infrastructure will change

– New features, even for traditional voice, will be developed on IP-based systems– New features and services – the “killer apps”

• IP (presumably SIP but also something else akin to Parlay) will replace SS7 for services and inter-node signaling


SS7 Service Architecture

Voice Trunks

Signaling Links

SSP SSP

STPSTP

SCP

STPSTP

Media Layer

Services Layer

Signaling Layer

ServiceNode

ServiceNode

Data Repository

SCP

Billing, Provisioning,

Customer Service


Voice Trunks

Signaling Links

SSP SSP

STPSTP

SCP

STPSTP

Media Layer

Services Layer

Signaling Layer

ServiceNode

ServiceNode

Data Repository

SCP


Customer Service

Intelligent Network• Centralized core data model for services• 0800, LNP, VPN, and mobile

only services widely deployed• Application and data intertwined, making

provisioning and back office difficult and costly• Expensive, proprietary platforms



Voice Trunks

Signaling Links

SSP SSP

STPSTP

SCP

STPSTP

Media Layer

Services Layer

Signaling Layer

ServiceNode

ServiceNode

Data Repository

SCP


Customer ServiceService Node• Most common model for PSTN services• Voice mail, calling card, call center• Separate provisioning, billing,

customer service for each platform• Expensive and non-integrated



Voice Trunks

Signaling Links

SSP SSP

STPSTP

SCP

STPSTP

Media Layer

Services Layer

Signaling Layer

ServiceNode

ServiceNode

Data Repository

SCP


Customer Service

Switch Based (CLASS, Centrex)

• Requires local provisioning on each

Class 5 switch

• No mobility

• Expensive, time consuming for new

feature deployment



Why Migrate Services to IP?

• Reduce back office costs• Vendor End of Life of IN platforms• Speed time to market by integrating provisioning systems with

Web front end• Reduce customer service call center expenses by automating

service delivery and turn up through the Web• Integrate AAA Internet infrastructure with voice services • Provide integrated services for voice and web customers• Provide mobility to subscribers• Integrate VPN, Work at Home and Mobile service offerings

The bottom line: Migration must serve a business purpose and provide new features and end-user benefits. Migration for migration’s sake is a tough case to make


VoIP Service Architecture

Media Layer

Services Layer

Signaling Layer

STPSTP STPSTPMGMG

MGC

Media

Signaling

SG SGSIP Proxy/GK

Core ServicesPlatform

ApplicationServer

ApplicationServer

ApplicationServer


Customer Service

MGC


Media Layer

Services Layer

Signaling Layer

STPSTP STPSTPMGMG

MGC

Media

Signaling

SG SGSIP Proxy/GK


ApplicationServer

ApplicationServer

ApplicationServer


Customer Service

MGC

Handset Based Services

• Unlike PSTN, digital signaling right to the

handset

• Could be a soft-phone (e.g. XP Client)

• Limited to specific local features




Media Layer

Services Layer

Signaling Layer

STPSTP STPSTPMGMG

MGC

Media

Signaling

SG SGSIP Proxy/GK


ApplicationServer

ApplicationServer

ApplicationServer


Customer Service

MGC

Edge Services

• Softswtiches (MGCs) and proxy servers

can operate edge oriented services

• Potentially difficult to provision and

manage as network scales up

• Service parity and consistency difficult

in multi-vendor networks


Media Layer

Services Layer

Signaling Layer

STPSTP STPSTPMGMG

MGC

Media

Signaling

SG SGSIP Proxy/GK


ApplicationServer

ApplicationServer

ApplicationServer


Customer Service

MGCCore Network Services

• Contain dial plans, central network routing data

• Open, standard platforms, databases

• Application servers can share information,

resources

• Web-based provisioning enables carrier to

offer subscribers convenience and self

serve customization while maintaining control



Services in the Converged Network

Initially…• Existing infrastructure will be used for existing apps• New infrastructure will be used for new apps

Moving Forward…• Service Mediation role is critical but barely understood• SS7 should terminate at the edge of the IP network• New enhanced service infrastructure needs to be defined and

developed


Leveraging SS7 – Do You Have A Choice?

• For PSTN interconnect, ISUP is required for even simple voice termination– This will not change– SS7 interconnect will always be required

• For Services, there are alternatives– Use TCAP-AIN as the universal services protocol across IP– Use full AIN from existing infrastructure– Use TCAP-AIN for very basic query response to legacy

infrastructure– Forget it – build a new IN based on DNS/SIP/Protocol X


Today’s Networks

PSTN:PSTN:98% of world’s voice traffic98% of world’s voice traffic

PSTN:PSTN:98% of world’s voice traffic98% of world’s voice traffic

VoIPVoIPVoIPVoIP

GW/SSGW/SS


Wither SS7?

• Approaches– Provide direct TCAP interfaces to the SoftSwitch layer

and have SoftSwitch function as full SSP• Most direct resemblance to PSTN• SoftSwitches are years from having full capability• Performance issues• Too much to build on a single platform

– Provide an Service Mediator that maps AIN to IP and holds call state (this is a true SCP implementation)

• Requires additional node in the network• Most scaleable• Requires standardization of service delivery profiles in SIP


Enabler: Service Mediation Server

• To enable migration, a service mediation server must live at the edge of the network

• Call states and triggers must map to the existing IN platforms, hold state, and delivery transaction based messaging to SoftSwitches

• Porting SoftSwitch SSP to the edge

• Transitionary platform? Or permanent?


Converged Network Service Delivery

Media Layer

Services Layer

Signaling Layer

SigGW

STP

STP SIP Proxy/GK

MG

MGC

STPSTPSSP

IPOAMPSMSSCP

PSTN OAMPSMS

Media: IMT

ISUP/SCTP

TCAP/SCTP

PSTN

IP

PSTN IP

Media: RTP

SIP, H.323

MGCP, MEGACO

SS7

ServiceMediation

AppServerApp

ServerApp

Server


SS7 Services for VoIP Networks

Media Layer

Services Layer

Signaling Layer

SigGW

STP

STP SIP Proxy/GK

MG

MGC

STPSTPSSP

IPOAMPSMSSCP

PSTN OAMPSMS

Media: IMT

ISUP/SCTP

TCAP/SCTP

PSTN

IP

PSTN IP

Media: RTP

SIP, H.323

MGCP, MEGACO

SS7

ServiceMediation

PSTN services are defined in SCP,

accessed through TCAP/SCTP

• 0800, LNP, Dialing Plans trigger a query

through TCAP/SCTP to SCP

• IP Application platform retrieves data,

translates to SIP, sends to SoftSwitches

AppServerApp

ServerApp

Server


VoIP Services for SS7 Networks

Media Layer

Services Layer

Signaling Layer

SigGW

STP

STP SIP Proxy/GK

MG

MGC

STPSTPSSP

IPOAMPSMSSCP

PSTN OAMPSMS

Media: IMT

ISUP/SCTP

TCAP/SCTP

PSTN

IP

PSTN IP

Media: RTP

SIP, H.323

MGCP, MEGACO

SS7

ServiceMediation

AppServerApp

ServerApp

Server

IP-based services are defined in Application servers and accessed Using SIP, DNS or Parlay• SSP issues TCAP query• Service Mediation gateway resolvesquery and accesses appropriate servers.


Enabler: DNS

• DNS provides the strongest alternative to TCAP for Query-Response applications• Current DNS infrastructure is default address resolver for IP• Many IN apps are address resolution:

– Basic Tandem Routing– Carrier Select– LNP– 800– CNAM

• Problem: Most IN apps require Call Models when anything advanced is delivered.• Very few IN apps are pure query response• Call Model Server + DNS


Where We’re Eventually Headed

VoIP:98% of world’s voice traffic

VoIP:98% of world’s voice traffic

PSTNPSTN

GW/SS


Hybrid Network Service Architecture

Call processing Layer

Service Layer

SSP

SCP

SSP

STP

Other Servers

MGC

STP/SG

PSTN

PBX

SIP

ServiceMediation

•IP SCP looks like an SSP to the legacy network

• Triggers in IP map to SIP


Towards a VoIP Service LogicTowards a VoIP Service Logic

SCP

IP STP

SIP GWPBX

Access Network

H.323 GK H323 GW

PSTN

Trunking GW

{H323}

{SIP}

Service Management

System

Real Time Billing

Server/OSP Server

H323 GW

{XML}

{RADIUS/OSP}

HP Open View

{SNMP}

{SIP or H.323}

{SIP}

{H323}

{XML} {SNMP}

{RADIUS/OSP}

Access Network

Access Network


Conclusions

• Models for SS7 in VoIP will depend on the carrier business model, service set, and installed network infrastructure

• Some SS7 service logic is required for PSTN interconnect• Major architectural options:

– Where to house the triggers– Where to terminate SS7 and AIN– Service Mediation function

• Optimal outcomes will leverage existing SS7 investments but not impose TCAP-AIN on IP components

• Service Core must move to IP, even if the IN services remain on the PSTN

© 2003, SS8 Networks, Inc. Proprietary. Do Not Copy or Distribute Without Permission.

Michael Gaines

+1 (613) [email protected]

Thank-you!

enhanced services for converged networks

Documents