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TECHNICAL SOLUTION FOR INTERNET GATEWAY (IGW) TOIMPLEMENET VOIP BY COMPLYING BTRC COMPLAINCE

COURSE TITLE:IP TELEPHONY (ETE 605)

PREPAED BY:SAYEF ALMAJIID: 063170056

SUBMITTED TO:DR. M RAHMAN

DEPARTMENT OF COMPUTER SCIENCE AND ENG INEERING

NORTH SOUTH UNIVERSITYApril 15, 2008

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Table of Content

Content Page1.0 Introduction 032.0 Key points of technical requirement for International Gateway (IGW)by BTRC

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3.0 Technical Solution 06 3.1 Standard New Generation Network (NGN) 06 3.2 Solution Requirements 07 3.3 IGW Solution 08 3.4 Networking Diagram for IGW 10 3.5 Interconnecting with H.323 Network 114.0 Conclusion 125.0 Bibliography 12

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1.0 Introduction

Bangladesh is a dense telecom populated industry which would like to deployInternational Long Distance Call Based on NGN with current requirement imposed byBTRC. In the requirement of whole network system now considering basically two partsin whole VOIP IGW & ICX platform like Voice Service Platform and Data ServicePlatform.

In Data service platform architecture, BTRC’s main concern is to monitor thewhole internet exchanges so that no voice traffic may pass through this platform. Allinternet service providers (ISPs) will be connected to three independent InternetExchanges (IX) and Internet Exchanges will be connected to Submarine InformationHighway or to internet Backbone with VSAT.

In Voice Service Platform architecture, BTRC considers three layers like,

Layer-1: Operators (Mobile, PSTAN/PLMN, & ISPs)

Layer 2: ICX / POI (Point Of Interconnection)

Layer 3: International Gateway.

In layer 1, basically all operators like Mobile Operators, PSTN/PLMN Operators and ISPswill reside. In Layer 2: ICX / POI, different operators like Mobile, PTAN/PLMN, and ISPswill be interconnected. The ICX / POI platforms will be connected with threeindependent IGWs (International Gateway). These International Gateways will throwthe voice traffic over IP to Submarine Cable Information highway Backbone or tointernet Backbone through VSAT (As Backup).

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2.0 Key points of technical requirement for InternationalGateway (IGW) by BTRC

The followings are some of the key points for implementing International Gateway byBTRC,

Type of switching technology

The IGWs must have both circuit switching and packet switchingtechnologies. The packet switching technology must have NGNfunctionalities. These two types of switching technologies may be combinedin a single system or in two separate systems located in the same premise.

All international voice calls including VoIP, originating from andterminating to Bangladesh, would be routed through the InternationalGateway Exchanges (IGWs). Prior approval of commission would berequired for international ‘Transit Call Services’ between two overseascarriers.

Interface Requirement

International Side

Both TDM and IP interfaces should be there at international side. Theconnectivity will be at STM-1, STM-4 or Ethernet level with SEA-ME-WE-4cable or any other level subject to availability of the submarine cablesystem(s) from authorized operator(s) in Bangladesh. However, for interfacerequirement, the IGW Licensee will arrange with Submarine Cable operatorand IGW Licensee’s overseas carrier.

National Side

Initially, only TDM interfaces will be used at National side to connect withthe Interconnection Exchanges (ICXs). The interface will be in STM-x levelas available with ICX. Any new interface in this respect may be installedsubject to permission of the Commission.

Signaling / Protocol

The CCS7 Signaling shall be used based on ITU-T White Book or laterversion. Moreover, it shall be backward compatible with Blue Book variantsprevailing in Bangladesh.

On International side, in addition to CCS7, all standard NGN signallingprotocol recommended by ITU-T and IETF shall be available. However, IGWLicensee is solely responsible for inter-working with overseas operators.

The NGN equipment must support IPv6.

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Speech Coding

The coding of TDM voice channels shall be according to A-law as per ITU-TG.711.

The IGWs shall have standard ITU-T recommended coding techniques for theconversion of TDM voice to packet as per clause-17 of this specification.

Network Security

For Next Generation Network, the IGW Licensees shall follow code ofpractice for information security as specified in ISO/IEC 17799 (laterrenamed as ISO/IEC 27002).

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3.0 Technical Solution

3.1 Standard New Generation Network (NGN)

NGN solution is based on the standard 4 layer NGN architecture namely edgeaccess, core switching, network control and service management, therebyachieving Technological Convergence, Network Convergence, and Service Convergence.These convergences bring us both challenge and opportunities as they enable onenetwork to offer more comprehensive services.

General Introductions to Carrier-class Component of U-SYS are as below:

Soft switch – offers an integrated solution for both fixed and mobile networkwhich is deployed in the control layer of NGN. Adopting DOPRA (DistributedObject-oriented Programmable Real-time Architecture) on OSTA (Open StandardTelecom Architecture) ensures the 6H features of the equipment - highavailability, high reliability, high real-time, high scalability, high load balance andhigh compliance to open system.

Universal media gateway - supports both narrowband and packet switchingfunctions with multiple access interfaces. The packet switching provides IPinterface to implement service traffic process and conversion betweenIP/TDM networks, which implements efficiently the inter-workingbetween different networks.

As a large capacity Universal Media Gateway (UMG) in NGN, it performsthe functions of subscriber access AMG, large-scale/mini-scale TMG, SignalingGateway NGN-enabled TDM switch, mobile network gateway, videointerconnection gateway (VIG), or a combination of above applications aswell.

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Signaling gateway - Besides built-in signaling function in UMG, SG asindependent signaling gateway is also available to fulfill the inter-workingbetween PSTN network and NGN so as to cooperate with the Softswitch andother IP-based database equipment (e.g. IP-HLR, IP-SCP and IP-SMSC). It providesbuilt-in STP function.

Multimedia resources server - Under the control of Softswitch, MRS providesmedium resource to packet network. Unlike the traditional peripherals based oncircuit technology, MRS is directly based on packet technology and eliminatesthe media stream conversion between TDM and IP, resulting in high qualitymedium flow on IP.

NMS - Network Management System uses standard protocol to manage all devicesin NGN, from Softswitch, various gateways, to IADs. iManager adopts layeredstructure, suitable for flexible and large scale networking.

NMS supports end-to-end service management, providing detailed deviceoperation information. The formerly complicated job of service configuration,IAD dispatching and trunk configuration can be performed easily through datasetting.

NMS supports network fault relativity analysis. The real source of alarming islocated among the group of related alarming messages. And more powerfully,the alarming relativity analysis among multiple devices is provided.

Network all-around performance analysis and syntheses is provided for theoperator to get real-time network performance information.

3.2 Solution Requirements

The each individual IGW (International Gateway) Platform should support the followingmodes.

Pure TDM traffic

In this mode, the IGWs should have the capability of managing and collecting intra-domain TDM traffic by the CS / MG which are owned by FT 100% TDM, including thetraffic between 2 MG and the traffic in a same MG.

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Mixed TDM and IP traffic

In this mode, the IGWs should have the capability of managing and collectingintra-domain TDM traffic by the CS / MG which are owned by FT 100% TDM,including the traffic between 2 MG and the traffic in a same MG as well as IP trafficfrom or to the other NGN domain, featured in red.

3.3 IGW Solution

The general IGW solution has two cases,

If there is STP in the current network or the current network capacity is very big, thesolution with standalone SG is recommended, the networking of this solution asfollowing:

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If there is no special requirements for signaling processing, the solution with built-in SG is recommended, and this solution have some advantages such as savinginvestment, especially suitable for distributed TG networking, the networking of thissolution as following:

Based on NGN architecture, a perfect IGW solution with the key components asfollow: SoftX3000 acts as call control center, UMG 8900 as TG, SG7000 as signallinggateway, SoftX3000 control UMG8900 with H.248, between SoftX3000 andSG7000 their protocol is SIGTRAN, SG7000 use No.7 inter-communication withPSTN.

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3.4 Networking Diagram for IGW

To meet the requirement for VOIP based IGW network, required equipments are Softswitch+ MG + SG + MRS + NMS + Router + Transmission Equipment (MW/Optical)

The following figure shows the NGN solution for VOIP IGW,

According to the requirement of this common platform of VOIP IGW where DataService and Voice services should be two different platforms and our proposednetwork solution will meet the requirement. In this proposed solution, in each IGW,there will be at least one Softswitch, which is used as the Call Server. But werecommend 2 Softswitchs that are used as the Dual-homing architecture toguarantee the network reliability.

The Softswitch has a built-in numbering database that can provide addressing,translation and routing facilities.

Generates CDRs and interworks with the FT billing system and perform interworkingbetween H.248 to MG. Interoperate with other Call Servers using SIP-T or SIP-I orH.323. Provide the call control function for the MG. Working as part of a resilient pairwith dual-homing for disaster recovery.

One MG, which are used as the UMG, are deployed in XXX.

Provide the build-in signaling gateway/ stand along signaling gateway to realize the SS7signaling translation between TDM and IP.

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Provide the interface between the IP/MPLS and the legacy TDM.

Provide virtual MG functionality so that different ports can be controlled by the differentcarriers. Connect to legacy PBX equipment with PRI interfaces.

One MRS for each softswitch, which will use as the Media Resource Servers. The MRSprovides customized announcements and tones for the whole network.

One NMS is used as the Network Management System. The NMS provides integratedManagement function for all network elements in the solution, presenting aseparate partitioned management view for each island.

3.5 Interconnecting with H.323 Network

The Softswitch may interwork with the H.323 network via H.323 protocol.

The soft switch sends RAS message to the opposite GK and exchanges Q.931 signalingwith the opposite GK or GW, performing call control, setting up H.245 channels, andnegotiating media capabilities and media channels. The soft switch supports routessignaling via GK or directly via gateway.

When a GK is used for routing signaling, all signaling interactions are performedbetween the soft switch and the opposite GK.

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Otherwise, when a gateway is used for routing signaling, except for the RAS sent to GKfrom the softswitch, all of the H.323 signaling are directly exchanged between thesoftswitch and the opposite H.323 GW.

When an operator interworks with his own H.323 VoIP network, he may avoidcomplex IP address translation by adopting unified IP address planning. If theassigned IP addresses of the VOIP network and the Softswitch network are indifferent address spaces, an NAT can be used for address translation between them.The call part of H.323 protocol family includes H.225.0 and H.245. The NAT isrequired to perform interworking between signaling stream and media stream ofVOIP. Residing at the application layer, H.225.0 and H.245 contain the IP addressesand port numbers of the called and calling gateways, therefore, to accomplish NATof H.225.0 and H.245, analysis on the application layer is needed, i.e. TheNAT should have H.323 application layer gateway (ALG) functionality.

4.0 Conclusion

The above discussion is just an overview on the possible way to implement VOIP throughInternet Gateway (IGW) by considering the rules and regulations provided by BTRC.

5.0 Bibliography

http:// www.btrc.gov.bd

http://en.wikipedia.org/wiki/