1. Introduction to 21CN Resilience Tim Hubbard Head of 21CN Solutions Strategy

2. Introducing the new architecture for PSTN 21CN Resilience and security Proposed topics for discussion

3. 21CN – Three key objectives Empower the end user with control, choice and flexibility like never before including communications from anywhere to any device Offer exciting new services for end user faster than before Reduce costs and grow cash cost savings - expected to amount to £1 billion per annum by 2008/9 Speed to market End user experience & empowerment Cost transformation

4. 21CN - evolution 21CN Today A single network that’s physically simpler and more reliable than our existing, complex infrastructure could ever be Up to 50 per cent fewer components in terms of switches, hubs, routers and suchlike. We will be able to deliver the next generation of converged services faster, more efficiently and more cost-effectively than ever before.

5. Dedicated hierarchical network of concentrators, local, trunk and tandem exchanges, with fixed relationship between all Dedicated network of trunks and circuits for voice traffic, each call has its own circuit Call control traffic and voice traffic directly connected together Call control and routing carried out by all switches in the network Complex Inflexible Restrictive Traditional PSTN architecture

6. 21CN PSTN – Separating speech and control Metro/Core MSAN 21CN PSTN OCP MSAN MSAN: Converts analogue PSTN speech into VoIP MSAN: delivers either copper based or fibre based services to end customers MSAN: Copper version has “combi card” functioning as DSLAM for broadband and concentrator for PSTN

7. 21CN PSTN – Separating speech and control Metro/Core MSAN 21CN PSTN OCP MSAN VLAN: Dedicated bandwidth across Ethernet backhaul network (MSAN to Metro Node) for carrying PSTN signalling traffic, PSTN speech traffic, broadband traffic, etc

8. 21CN PSTN – Separating speech and control Metro/Core MSAN 21CN PSTN OCP MSAN Call Server: Carries out call control, processing dialled digits, setting up and tearing down telephone calls, etc Directory: Holds all PSTN numbers, whether they are on 21CN, legacy PSTN, other CP network.

9. 21CN PSTN – Separating speech and control Metro/Core MSAN 21CN PSTN OCP MSAN Session Border Controllers: Gateway for telephone calls between 21CN and legacy PSTN/other CP networks Signalling Firewalls: Gateway for signalling traffic to/from 21CN call server to set up telephone calls to/from 21CN to legacy PSTN and other CP networks

10. 21CN PSTN – Separating speech and control - 21CN to 21CN call Metro/Core MSAN 21CN PSTN OCP MSAN

11. 21CN PSTN – Separating speech and control - 21CN to 21CN call Metro/Core MSAN 21CN PSTN OCP MSAN

12. 21CN PSTN – Separating speech and control - 21CN to 21CN call Metro/Core MSAN 21CN PSTN OCP MSAN

13. 21CN PSTN – Separating speech and control - 21CN to 21CN call Metro/Core MSAN 21CN PSTN OCP MSAN

14. 21CN PSTN – Separating speech and control - 21CN to OCP/PSTN Metro/Core MSAN 21CN PSTN OCP MSAN

15. 21CN PSTN – Separating speech and control - 21CN to OCP/PSTN Metro/Core MSAN 21CN PSTN OCP MSAN

16. 21CN PSTN – Separating speech and control - 21CN to OCP/PSTN Metro/Core MSAN 21CN PSTN OCP MSAN

17. 21CN Resilience De-couple each “layer” Recover at the lowest level possible Maintain service availability across 21CN Physical:Building, ducts, equipment, fibre, etc Logical:Optical and packet protocols SDH/WDM Service Ethernet MSAN MetroCore MPLS D-WDM

18. 21CN Resilient PSTN Core Node Tier 1 MSAN Metro Node Voice Controlled by call server in Metro/Core Nodes Each MSAN has at least two routes to its primary call server Each MSAN will have a primary and secondary call server FMSAN CMSAN

19. 21CN Resilient PSTN Core Node Tier 1 MSAN Metro Node Voice Controlled by call server in Metro/Core Nodes Each MSAN has at least two routes to its primary call server Each MSAN will have a primary and secondary call server FMSAN CMSAN

20. 21CN Resilient PSTN Core Node Tier 1 MSAN Metro Node Voice Controlled by call server in Metro/Core Nodes Each MSAN has at least two routes to its primary call server Each MSAN will have a primary and secondary call server FMSAN CMSAN X

21. 21CN Resilient PSTN Core Node Tier 1 MSAN Metro Node Voice Controlled by call server in Metro/Core Nodes Each MSAN has at least two routes to its primary call server Each MSAN will have a primary and secondary call server FMSAN CMSAN X

22. 21CN Reliability, continuity and resilience 21CN is a private IP network, NOT the Internet 21CN separates network and services for increased resilience and faster service delivery 21CN is engineered with high availability and resilience 21CN Assurance agreed with Central Sponsor for Information Assurance

23. Webcall update 18 AprilProduct retirements 24 April21CN overview 2 MayMigration process 22 MayCPE compatibility testing programme 31 MaySwitched-on communications campaign 20 JunePathfinder programme overview 9 JulyPreparing for 21CN migration 26 JulyBroadband migration programme 2 August21CN resilience and security 27 Sept tbc Migration portal overview Industry invited to suggest topics of interest …further webcalls will be scheduled for the rest of 2007

24. Sources of further information Information and support for communication providers on the 21CN programme: http://www.btwholesale.com/consult21 The independent public information website covering the process of migration: http://www.switchedonuk.org For general information about BT’s 21CN programme go to: http://www.btplc.com/21CN/

25.  Answers Questions