Difference Between Ngn And Legacy Tdm Network

Network Systems Division

Tekelec Packet Telephony

Next Generation Networks: Migration from Circuit to Packet – An Overview

White Paper 111700R1

Introduction The world’s telecommunications market is facing dramatic change. In the U. S. the Telecommunications Act of 1996 has served as a key catalyst. Furthermore, similar regulatory events are spreading this wave of change around the world. The net result is that the telecommunications services market has become increasingly competitive. This new level of competition, combined with the tremendous growth of the Internet and its associated technology has dramatically changed the incumbent service providers’ world. New competitive long distance and local service providers are challenging these venerable institutions. With these new competitors have come innovations in products, services, and pricing. A key enabler of this innovation is the convergence of voice and data. Whether its combining voice and data traffic in the carrier backbone or in the local loop, every carrier is evaluating the economies and flexibility of a converged solution. This paper provides a view of the telecommunication’s network migration that will occur, as new services are required in an ever demanding and changing marketplace.

Begin with the end in mind: Where are we going? Key characteristics of Next Generation Networks (NGNs) The demands on the telecommunication’s networks today and in the future are reflected clearly in the societal changes around the world. Customers of all services have historically wanted more for less, more flexibility, and sometimes just “more”! This can certainly be seen in the rapid growth of mobile network usage. The mentality of anytime, anywhere is becoming prevalent around the world – the primary differences between regions being largely a matter of degree. Also, customers are seeing innovation across all areas of consumer goods and services with “just in time” services tailored to their specific needs and timeframes. These too will be key demands placed upon telecommunications networks as they evolve. Key characteristics of NGNs are: • Geographic transparency: boundaries are disappearing and economic benefits independent of service “density” must be realized • Transport efficiencies: transport costs (price/bit) are continuously declining, NGNs must share these efficiencies – for both bearer and signaling traffic • Internet technology economics: leverage services and service delivery through the Internet, as well as the “silicon economics” of Internet hardware (servers, etc.)as memory and processor price/performance improve • “Old World” to “New World” interoperability: existing PSTN infrastructure, and its associated investment must be fully utilized Global resources – global reach The network of tomorrow will be the conduit to resources around the world. Regardless of location, regardless of technology, the uniform availability of communications services will be the fundamental differentiator between today’s and tomorrow’s networks.

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This reality will be based upon standards based transport, signaling, services, and many more aspects. Figure 1 below illustrates this from a high level.

Global Packet Telephony Network

Service Service

Service Service

Service

Service

Universal Services: Location independent

access

“inter-service” connections service access sessions inter-party communications Figure 1

Where are we today? In the long distance market, packet transport offers the “promise” of lower costs over traditional time division multiplexing (TDM) transport. This has resulted in an arbitrage “play” by upstart carriers as they offer long distance voice for almost free. Packet technology in the form of the Internet has also been created major disruptions (or opportunities, depending on your perspective). In the late 90’s ISPs began delivering data to both business and residences as demand for the Internet rose. As data traffic grew, forecasts of data surpassing voice abounded. With the continuing explosion of data traffic, the idea of a common transport gained momentum.

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In the local carrier market, Internet traffic is causing major concerns and driving reengineering of local End Office switches. These switches were engineered for traditional voice calling patterns. In particular, characteristics such as frequency of calls and call hold times are markedly different with the added load from Internet dial traffic. In fact, the steady increase in Internet traffic threatens to exceed these switches capacity. One avenue of relief for this situation is the deployment of residential ADSL. The leading technology in this market is an “always on” connection, but the traffic does not go through the local voice switch. Rather, the local Internet traffic is terminated in the local central office (CO) by a digital subscriber loop multiplexer or DSLAM. From the DSLAM the traffic is typically multiplexed into an ATM network and transported to an Internet Service Provider (ISP). Today, this ATM network is separate from the voice network. Within the Internet infrastructure, as well as in the enterprise domain, Internet Protocol (IP) is the dominant transport. Given that both ATM and IP have strong supporters, there is significant discussion and debate over what is the “best” approach, especially in replacing legacy TDM networks. In fact, technologists from both carriers and vendors, as well as industry “experts” are hotly debating over the choice of ATM versus IP as the primary transport method.

NGN Migration Key considerations in the evolution As carriers move towards solutions using new technologies and architectures, the success or failure of these solutions is dictated by many factors. In the case of the NGNs and “deconstructed” switch / packet network replacing the circuit switch / TDM network, it is important that these key benefits be delivered: -

Investment protection Operational and capital costs savings Carrier grade reliability Improved service creation capabilities Scalability Improved product selection/choices

Investment Protection Today’s carriers today have billions of dollars invested in their existing networks. It would be fiscally irresponsible for their management to even consider installing a completely new network, and discarding their network. In fact, it is critical that any new network technology, whether it is “simply” a new network element (NE) or an entire “sub-network”, interoperate and leverage existing capabilities. With this in mind, incorporating NGN components based upon standard, open protocols is the first step to protecting a carrier’s investment. Compatibility with SS7 and intermachine trunk (IMT) requirements are fundamental tenants to supporting a smooth migration to a NGN. This compatibility insures basic call setup and teardown, as well as access to existing Advanced Intelligent Network (AIN) services such as local number portability (LNP), free call (ex. U.S. 8xx calls), etc. An example of how this could be

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accomplished is shown in Appendix A. Additionally, from an operational perspective, interoperability with existing Operational Support Systems (OSS) is required before the NGN can actually be placed into service. Tekelec’s NGN components, the IP7 Secure Gateway, IP7 Front End, and VXi Media Gateway Controller family are comply with industry standards in signaling and transport, as well as supporting various management capabilities. Furthermore, Tekelec will continue to enhance and develop capabilities in this area to insure that its customers receive the maximum return from existing infrastructure investment in transition to an NGN approach. Operational and Capital Savings The primary driver behind NGNs is, predictably, economics. Whether the horizon is short term or long term the fundamental “raison d’être” is lower costs, higher revenues, or both. In as much as most carriers currently own and maintain both voice and data networks, it is reasonable to project possible savings on the order of 50% when the two networks are combined. Purely from a acquisition cost perspective, the NGN equivalent of a circuit switch – softswitch/MGC and MGs, together can be less than one third the cost. Furthermore, given the distributed nature of NGNs, and the incremental growth characteristic, capital budget management and growth planning are both simpler. Rather than large purchases (i.e. major switch upgrades), incremental upgrades to media gateways or additional media gateways occur. Since NGN solutions are premised upon open standards and are closely linked to Internet technologies, significant cost savings will occur over the life of the network. Open standards create choice and encourage competition -- a strong determinate of pricing trends. With the leverage of Internet technologies, whether it be software (“web” technology, etc.) or hardware (server and mass storage technologies, etc.) there will be dramatic cost and innovation benefits realized – similar to those found in the data networking market with routers, switches, and PCs. Carrier Grade Reliability Much of the success of today’s telecommunications carriers revolves around the fact that in most industrialized countries the telephones always work. Carrier grade standards for availability are typified by “five nines” or 99.999% uptime. To achieve this high level of reliability, equipment manufacturers and their carrier customers have developed products, architectures, and processes whose mission is focused on maximizing network uptime. From a product perspective, reliability is typically increased by redundancy – redundant processors, links interfaces, hard disks, power supplies, etc. These components are rigorously tested by manufacturers who have implemented the most stringent quality standards, such as ISO 9000 and TL9000. System reliability is also addressed by implementing “mated pairs”, i.e. redundant systems often operating in synchronization.

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Architecturally speaking, redundancy is again the often the approach of choice. System reliability is addressed by implementing “mated pairs”, i.e. redundant systems often operating in synchronization but geographically separated with redundant, diversely routed links providing the interconnection. This continues to be the standard industry practice and is part of Tekelec's network proposals. Tekelec has a celebrated reputation for providing carrier grade reliability in its products. The IP7 Secure Gateway platform has both calculated and field proven reliability of 99.99999%. The VXi MGC is based on carrier grade computing platforms from Sun Microsystems – the Netra series. The VXi MGC system is configured with redundant (active/standby) processors, redundant Tone and Announcement Servers, and redundant internal LANs with companion redundant hubs and routers. All of Tekelec’s solutions are carrier grade and meet such stringent requirements as the U.S. carrier NEBS certification. Tekelec will continue to work with its customers in meeting or exceeding all of the necessary requirements. Scalability Historically, telecommunications networks have scaled rather poorly and often at significant cost to the carrier. Switches were either “over provisioned” to support growth or they were upgraded to include additional line and trunk cards, additional call capacity. If capacity was required remotely from the serving switch, “remotes” or digital loop carriers were implemented. These solutions were usually expensive from both a capital and operating perspective. In contrast, NGN architectures support incremental growth in ports (lines or trunks), in call capacity, and in extension to new remote locations. With its distributed nature – softswitch or media gateway controller, media gateways and signaling gateways all interconnected via a packet transport – an NGN solution offers both incremental growth and the ability to leverage advances in technology without the “wholesale” changes that are typical of traditional circuit switches. Tekelec’s products and network proposals offer industry-leading scalability. The IP7 Secure Gateway scales from 2 to 450 SS7 links, while the VXi MGC offers in-service upgrades from 250,000 BHCA (Busy Hour Call Attempts) to nearly 1million BHCA. The NGN scales in a straightforward fashion as described above: either by incrementally adding capacity to existing media gateways, or by adding media gateways. Enhanced Services can be introduced or expanded using existing Network Elements (NEs), such as SCPs, or in the future by adding Feature/Application Servers, and Media Servers. Improved Product Selection Historically, the telecommunications network has relied upon a few large suppliers. This fact along with the highly integrated, “big iron” nature of circuit switches has led to carriers being overly reliant on these large suppliers. With long development cycles for new features, and expensive upgrades to support these features, carriers often felt captive to the vendors of their install base.

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The NGNs distributed, standards-based approach is the key to freeing carriers from this tenuous situation. Ideally, products that are standards-based will interoperate and offer carriers the best choices in technology, scalability, and price. However, given the relative immaturity of the NGN market and their associated standards, the telecommunications industry will face a period of standards “convergence” over the next few years. As stated here several times, Tekelec’s approach is founded on standards-based implementations. The VXi MGC supports Q.2931, MGCP, and SIP, and will evolve as these protocols mature. This is affirmed by the extensive list of media gateways supported. Not relying on a single transport technology or single vendor, the VXi MGC supports ATM and IP MGs supplied by leading manufacturers, such as Newbridge (Alcatel), Tellabs, and Cisco. In addition, support for integrated access devices from Woodwind and Mariposa complement this broad offering. A few words about Quality of Service There are a few key requirements to consider when evolving or replacing an existing service. Foremost is meeting or exceeding customer’s requirements. This is particularly true as it relates to telephone service. Though the level of quality varies by technology type (e. g., wired versus wireless) and network implementation, customers will continue to expect steady improvement in both the actual voice quality and voice services. The companion requirement to meeting customer expectations is meeting stockholder expectations, i.e. the new approach must be financially sound. A key premise of NGNs for voice is the guaranteed level of service. Contrasting today’s circuit based networks with the most visible packet based network – the Internet – a critical difference exists. The Internet is based upon a message delivery “philosophy” of “best effort”. In other words, accurate and timely delivery is not guaranteed. On the other hand, while a circuit switched network may not always deliver a call due to congestion, once a connection is made, the circuit is more often than not reliable. NGNs for voice implemented over packet networks, whether using ATM or IP, depend on timely delivery of the voice packets (one way latency, round-trip delay, echo delay, etc.). There are industry wide discussions on how this is best accomplished. For ATM networks, there are clearly defined approaches to insure both quality and timeliness. However, for IP networks there is significant debate on various schemes, such as MPLS, diffserv, etc., and there is no clear choice in evidence today. A standards-based approach is even farther away. Tekelec’s IP7 Secure Gateway and VXi MGC interface to packet networks; however, they assume that these networks provide the necessary quality of service. The media gateways supported by Tekelec are an integral edge component of these packet networks, and as such interoperate with the core transport to deliver the desired level of reliability and performance. Tekelec will work with its customers and MG partners to assist in creating an NGN network that meets both today’s and tomorrow’s customer expectations.

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Migration architectures Voice Trunking: Tandem Replacement The first step supported both by the technology available and industry consensus is the migration of the voice trunking network from TDM transport to packet transport (ATM or IP). This is demonstrated in the following two illustrations, Figure 2 and Figure 3: SS7

STP STP

STP End Office

End Office

SCN

SCN

TDM

TDM Access Tandem TDM

STP

STP

Access Tandem

Access TDM Tandem

TDM End Office

SCN

Traditional TDM Architecture

SCN

End Office

Figure 2

IP7 SG SS7

SS7 TALI/SCTP

STP

STP End Office

End Office

SCN TDM

TDM

End Office

VXi MGC Media Gateway

Media Gateway

SCN

MGCP UNI 4.0

SCN Media Gateway

Packet Transport Media Gateway (ATM/IP)

TDM

SCN Voice Trunking with Packet Transport

End Office

Figure 3

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Effectively, TDM trunks from End Offices, which typically connect directly to a Tandem or Transit switch network, now use a distributed transport and switching network, comprised of a packet transport and a softswitch / media gateway controller for call control. Examining the architecture, the three key components and their roles are: • Media Gateways: TDM to Packet translation for the bearer channel, and ingress/egress to the packet network. These MGs are of the trunking gateway variety, meaning they terminate TDM trunks. • Signaling Gateway: Conversion of SS7 signaling from TDM to packet, and management of SS7/ISUP country variants. Packetized SS7 information is forwarded to the MGC via standard interfaces. Today, this includes TALI, and in the future SCTP, pending its ratification. • Media Gateway Controller: Call control, as well as including trunk management, screening, number translations, and correct trunk routing. The MGC controls the MGs via standards such as Q.2931 for ATM MGs and MGCP for IP MGs. Note: Tekelec will offer standard based interfaces where available. In cases where customer’s require capabilities not yet standardized, Tekelec will either develop and promote an open standard (e.g. TALI), or will use the latest DRAFT of a potential standard.

While leveraging packet transport economies, this voice trunking approach also allows use of existing services provided by SCPs, Service Nodes, etc. Voice over IP: End Office Replacement The transition to End Office support is based on the addition of two devices: •

Media Gateways (MG): These are of the access gateway variety and perform the functions common to the trunking gateways of TDM to packet translations. However, these devices continue terminate analog local loops to support traditional telephone handsets. Variations, based on the nature of the local loop and the intelligence of the customer telephone device are discussed below.

•

Application/Feature Server (AS/FS): This is a shared resource associated with the packet transport, but one that interoperates with the MGC or softswitch. The interface will typically be a SIP interface, but the AS/FS will also support the implementation of the next level of call control features, such as call waiting, call forward no answer, caller ID, etc.

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The Voice over IP architecture is shown below in Figure 4: IP 7 SG SS7

SS7 TALI/SCTP

STP

End Office

STP VXi MGC

SCN TDM

Media Gateway

Access Gateway TDM

End Office

Application Server

MGCP/ UNI 4.0

Packet Transport (ATM/IP) Media

SCN

Media Gateway Media Gateway

TDM

SCN

Gateway

End Office

Access Gateway

SCN End Office

SIP

Voice Trunking and End Office Support with Packet Transport Figure 4

The current state of the industry for End Office support can best be characterized as experimental. While there are actual implementations of PC to PC and PC to phone, there are no carrier grade installations of true “black phone” to “black phone” with the requisite services supported. Historically, the PC to PC approach has been based on H.323, with the abundant availability of Microsoft’s NetMeeting application. There is also significant development underway to implement SIP and SIP phones as the “next generation” of customer telecommunications devices. This model is based on the assumption that the end user device is significantly more intelligent than today’s telephone handset. Due to the huge number of installed telephones, the migration to “intelligent” phones, ex. SIP phones, the requirement for continued support of “black phones” will remain for many years. Another emerging technology well suited to the softswitch/End Office approach is voice over DSL (VoDSL). In a VoDSL application the VoDSL gateway can support either a traditional TDM interface (GR-303) to a standard End Office switch, or it can support a suitable “packet” oriented interface such as Media Gateway Control Protocol (MGCP). With the advent of voice and data integrated access devices leveraging the bandwidth available from digital subscriber loop technology, another viable component, used as a media gateway, becomes available. With this in mind, it is critical that any NGN implementation provide the flexibility to support whatever access technology is predominant. Tekelec is basing its development, recommended architectures, and focus on standards. This will allow a straightforward migration to various access technologies as they implement standard interfaces such as MGCP and SIP. Tekelec is actively working with customer’s today to move towards viable, deployable capabilities for End Office applications.

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Converged Services: PSTN/Internet Interworking Another step in NGN migration is the incorporation of the Internet into the overall telecommunications architecture. One of the early applications involving softswitches has been the offloading of traffic destined for the Internet from the circuit switched network. This application, from an access perspective could be viewed as the initial capability of the converged services aspect of NGNs. In reality, this capability serves primarily to minimize a carrier’s internal problem (i.e., Internet traffic causing congestion in switches designed for voice traffic with 3-minute hold times), but does not offer any new capabilities to customers. New services are possible, however, with a converged services network. Primarily, the new services will involve logically coupling Internet sessions with the voice capability of the PSTN. Examples include: •

Internet Call Waiting – allowing an incoming call alert to be displayed on a PC window while maintaining an Internet connection. Various options regarding call acceptance are possible. Click to talk – the ability to initiate a voice call while visiting a web site supporting a voice dialog for ordering, customer service, etc. Unified Messaging – providing true integration of various messages into a single multimedia “mailbox” and offering translations between the media (voice to text, text to voice, etc.) Find me, follow me – expansion of existing services to include recognition of a user’s online presence as a contact reference / location. Click to fax – an ability similar to click to talk, but one that creates and sends a fax, typically based upon the “sending” web site content to a user supplied number from an Internet session. Content to Audio – retrieval of Internet based content in an audio format to a user-selected device.

• • • • •

The converged services approach would most likely be an incremental migration from the previous VoIP solution to include additional devices such as: •

Mediation media gateway – “access point” to Internet transport services with appropriate firewall capabilities

•

Media servers – devices capable of offering retrieval and translation of content to differing media.

In addition, there will be linkages between Internet, SCN, and VoP to support the capabilities listed above as well as other services. This high level architecture is shown in Figure 5 below:

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IP7 SG SS7

SS7 TALI/SCTP

STP

End Office

STP VXi MGC

SCN TDM

Media Gateway

Access Gateway TDM

Media Gateway

SCN

SIP

End Office

Application Server

MGCP/ UNI 4.0

Media Gateway

Packet Transport MGCP, SIP (ATM/IP) Mediation Gateway

SCN

Media Server

Access Gateway

End Office

Web PC

Pager

Internet PDA

SIP Phone

Converged NGN/Internet Figure 5

Services today and in the future A key issue in the migration from today’s PSTN to any NGN is the creation of new services, while maintaining existing services. This service compatibility requires welldefined interface points and clear protocols between the two environments (PSTN and NGN). For this reason, NGNs which implement some form of signaling gateways and SS7 interconnects, along with “higher-up-the-stack” capabilities such as TCAP and AIN features, form the initial services platform. Once this capability is insured then implementation of additional services databases and the requisite interoperability rules and protocols can be defined.

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The vision of the NGN is that these services can reside anywhere and be accessed by anyone. (Authorization is assumed). In fact, a new market opportunity for offering services is likely to develop form today’s nascent application service provider (ASP) space.

Conclusion The future of NGNs is from one perspective assured: the traditional TDM network will be replaced, from another perspective nothing is sure, but what exactly will an NGN look like? When will NGNs be implemented? And, what will be the key services of the future? These and other questions will be answered in the coming months and years. For now, it is critical that equipment suppliers and carriers alike understand the dynamics of the changing telecommunications landscape. Deregulation has opened up this market for aggressive and agile entrants who do not have the burdensome capital investment in traditional networking equipment. These new entrants - CLECS and ICPs, are dramatically affecting the market for both the every day subscriber and the incumbent carriers. “Internet-time” has reached the carrier market. Whether the architecture of the “new world” replaces the “old world” in next five years or ten years, change is certainly here.

Appendices

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Appendix A

PSTN to IP to PSTN Message Flow Diagram with LNP Query SCP SCP 8

ISUP/TCAP/SS7

ISUP/TCAP/SS7

IP IXC Signaling 3,22,27 MG Controller 6,14,19,26,29 MG Controller Gateway ISUP/TCAP/IP SIP+ [MGC] [MGC] [SG] 4,5,15,16,20,21

Signaling Gateway ISUP/TCAP/IP [SG]

7,9,12,18,25

MGCP

SIP+

2,23,28

ISUP/TCAP/IP

ISUP/SS7

IP Network

FGD Trunks

SSP 1

LEC A

Source: IN Forum, IN-IP Workgroup

Media Gateway [MG]

MGCP

FGD Trunks

SSP

10,11

MGCP

[MG]

LEC B

RTP FGD Trunks 11 - (RTP connection)

[MG]

SSP

LNP Message Flow Network Configuration

LEC C

Figure 6

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13,17,24

ISUP/SS7

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PSTN (call origination) to VoIP to PSTN (call destination) with an LNP Query LEC A

Origination Origination Media Media Gateway Gateway Controller

Origination Signaling Gateway

STP

SCP

Terminating Terminating Terminating Signaling Media Gateway Media LEC B LEC C Gateway Controller Gateway

STP

OFF-HOOK 1

IAM

2

IAM ISUP/IP - IAM

3

CRCX

4

ACK

5

INVITE

6 TCAP/IP (LNP)

7

TCAP (LNP) TCAP (LNP) TCAP (LNP-Response)

8

TCAP TCAP/IP (LNP-Response) 9 10

CRCX ACK

11 12

ISUP/IP - IAM IAM

13

IAM 100 TRYING

14 15

MDCX ACK

16

ACM

17

ACM ISUP/IP (ACM)

18 19 20 21 22

180 RINGING MDCX ACK ISUP/IP (ACM) ACM ACM

23 ANM

OFF HOOK 24

ANM ISUP/IP (ANM)

25 26 27

200 OK ISUP/IP (ANM) ANM

28

ANM ACK

29

Figure 7 – LNP Message Flow Diagram Call Scenario B Source: IN Forum, IN-IP Workgroup

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LNP Service Delivery - Message Flow Description The message numbers contained in this message flow description correspond to the numbering in the LNP Message Flow Diagram, refer to Figure 7. The message numbers also correspond to the LNP Network Diagram, refer to Figure 6. Note: This Call Scenario does not contain the call tear-down messaging at this time. 1. Caller goes off hook. 2. LEC A sends SS7 IAM to the originating SG (OSG). 3. The OSG receives and encapsulates the IAM in an IP packet (SIGTRAN), and sends it to the originating MGC (OMGC). ( The SG is shown as a separate physical element and uses the open interface being developed by IETF/SIGTRAN *** The SG may be integrated with the MGC, MG, or an integrated MGC/MG *** ) 4. The originating MGC (OMGC) (Media Gateway Controller) parses the IP encapsulated IAM, and sends a CRCX (create connection - MGCP) command to the originating MG (OMG). 5. The originating MG (OMG) returns an ACK acknowledgement containing the originating MG (OMG) RTP port address to be used for the call. 6. The originating MGC (OMGC) determines where the call is destined and sends an INVITE command to the destination Media Gateway Controller (DMGC) with the encoded IAM. 7. Destination Media Gateway Controller (DMGC) receives the INVITE and parses the IAM portion and determines the NPA-NXX resides in a ported MSA. The destination Media Gateway Controller (DMGC) launches a TCAP/IP (IP encapsulated TCAP SIGTRAN) LNP query to the destination Signaling Gateway (DSG). 8. The DSG removes the IP encapsulation and sends an SS7 LNP TCAP query to the LNP SCP. The LNP database may return the Location Routing Number (LRN) or the original dialed digits. In this instance, the called party has changed from Carrier B to Carrier C, thus an LRN for Carrier C is returned in the LNP TCAP response. 9. The DSG encapsulates the LNP response in an IP packet and sends it to the destination Media Gateway Controller (DMGC). 10. The destination Media Gateway Controller (DMGC) determines the destination MG (DMG) based on the LRN and sends a CRCX (create connection - MGCP) command to the destination MG connected to Carrier C. 11. The destination MG (DMG) establishes an RTP connection with the originating MG (OMG), and sends an ACK (connection acknowledge) to the destination Media Gateway Controller (DMGC) containing the destination MG RTP port information used for the IP connection. 12. The destination Media Gateway Controller (DMGC) updates the IAM based on the LNP query response, encapsulates it in an IP packet, and forwards it to the DSG. 13. The destination SG receives the encapsulated IAM, formats an SS7/IAM message and forwards it to Carrier C. 14. The destination Media Gateway Controller (DMGC) sends 100 TRYING to the originating MGC (OMGC). The 100 TRYING message contains the destination MG RTP port information to be used for the call.

16

15. The originating MGC (OMGC) sends an MDCX (modify connection) command to the originating MG (OMG). 16. The originating MG (OMG) establishes an RTP connection to the destination MG and sends an ACK (connection acknowledge) to the originating MGC (OMGC). 17. LEC C returns an ACM to the SG. 18. The originating Signaling Gateway (OSG) encapsulates the ACM and sends it to the destination Media Gateway Controller (DMGC). 19. Destination Media Gateway Controller (DMGC) sends 180 RINGING message to the originating MGC (OMGC) containing the encoded ACM. 20. The originating MGC (OMGC) sends a MDCX (modify connection - voice cut through) to the originating MG (OMG). 21. The originating MG (OMG) sends an ACK (connection acknowledge) to the originating MGC (OMGC). 22. The originating MGC (OMGC) forwards the updated ACM to the OSG. 23. The originating SG removes the encapsulation and forwards the ACM to Carrier A. 24. The Called Party answers the phone. Carrier C sends an ANM to the destination SG. 25. The destination SG encapsulates the ANM (SIGTRAN), and sends it to the destination Media Gateway Controller (DMGC). 26. Destination Media Gateway Controller (DMGC) sends 200 OK command to the originating MGC (OMGC) containing the encoded ANM. 27. Originating MGC (OMGC) receives 200 OK command, extracts, updates, encapsulates and forwards the ANM to the OSG. 28. The origination SG strips off the IP encapsulation and forwards the ANM to Carrier A. 29. The originating MGC (OMGC) acknowledges the 200 OK by sending an ACK message to the destination MGC. ************** Call Setup Complete************* Source: IN Forum, IN-IP Workgroup

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Appendix B Techno-economic discussion for Next Generation Networks (NGN). Today’s circuit switched architecture(s) have evolved over the last 100 years; however, this evolution compared to the rapid evolution seen in the PC and Internet worlds has occurred at a snail’s pace. The lifecycle of equipment in the traditional telecommunications marketplace is measured in decades. Contrasting that with “Moore’s Law” in the PC market place and “Internet time” in the Internet communications space illustrate a key motivator for NGNs. There are at least four key techno-economic drivers for NGNs: • Costs (capital and operational) • Price/performance • Standards • Speed of innovation and introduction of services With the dramatic hardware technology changes in the PC world (“obsolescence,” typically in 18 months) and the rapid innovation within the Internet, both hardware and software products are on dramatically different price/performance curves from traditional telecommunications equipment. Industry analysts often quote IP network capital costs to be as little as 50% of comparable switched network costs. Furthermore, the operational costs of combining (i.e. converging) the traditional disparate voice and data networks ostensibly could be in the 50% range as well. These cost advantages are key drivers for NGNs; however they are not the only drivers. Historically, the traditional telecommunications networks depended on a select group of vendors offering closed, proprietary solutions. These seldom interworked, except at clear lines of demarcation in standard interfaces. This market structure favored vendors and allowed significant control of product evolution by these same vendors. Today’s PC and Internet markets are based on “consumer” market quantities (eg. millions and millions) and rapidly evolving standards – but standards nonetheless. Since the NGNs leverage significant aspects of these two areas, the volume (that drive prices down) and the standards (that promote interoperability) form yet two more techno-economic reasons for NGN implementation. The fourth and perhaps the most unproven reason for migration to NGN implementation is the ability of these new networks to support rapid introduction of new and different services. Consistent with the characteristics of Internet applications, however, this “promise” has yet to be realized simply because NGN’s are still in their infancy. If Internet technologies (ex. NG HTML, DNS, LDAP, etc.) are effectively used, rapid, innovative services may prove to be the most compelling reason for NGNs. Regardless of the level of NGN “integration” into today’s existing circuit switched networks, benefits will be realized. However, as the NGN technologies mature and are deployed the more complete the move to NGNs, the more substantial will be the benefits.

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