1. NGN Interconnect Update JOINING THE THREADS 25 May 2005 FOR WG DISCUSSION ON 3 JUNE

2. INTERCONNECTION TODAY Distance and Element Based Voice Stovepiped (snapshot below, as example) NNIs for Frame and ATM Partial Private Circuits using PDH/SDH Site Type“Ex-DLE RCU”“DLE”“Tandem”“NGS” # SitesN/A21362 # Sites w/ ISI3282656 ISI E1 Volumes: -2,4491,59854,455 IEC E1 Volumes: 1,6862,16335319,616

3. NGN INTERCONNECT Converged Point of Handover ­ Multi-service pipe between two operators ­ Architecture (i.e. standards) to be agreed at TSG ­ In 21CN, BT side will generally be at a fibre MSAN Service Specific Conveyance ­ Multiple services will be conveyed across a PoH ­ Some will be price controlled (e.g. PSTN), others won’t ­ Some will require service specific network elements ­ Some services can be defined today, others can’t For discussion purposes. No implementation assurances

4. CONVERGED POINT OF HANDOVER Convergence requires a glue layer ­ Long term vision is native Ethernet, but ­ Some services may still require SDH ­ And most UK networks are SDH based BT Proposal to NICC/TSG ­ Hybrid: SDH, Physical Ethernet and/or Ethernet VLANs ­ Provides implementation flexibility ­ Allowing for technology evolution ­ But defines Ethernet VLANs as the glue layer For discussion purposes. No implementation assurances

5. GigE Physical IP SDH Physical VCAT ATM ATM Backhaul Services GFP Ethernet VLAN IP VCAT ATM GFP Ethernet VLAN IP PSTN/ISDN Services Other Services on IP TDM Services PSTN/ISDN Services Other Services on IP ATM Backhaul Services TDM Services DAY ONE PoH ARCHITECTURE For discussion purposes. No implementation assurances

6. HOW DEEP SHOULD PoH BE? BT proposed PoH at ~130 Metro node sites Some Operators want deeper PoH, because: ­ They have existing fibre assets that may be stranded ­ They want to leverage LLU investments ­ They want to intermediate the wholesale market ­ They believe conveyance will be cheaper Ofcom wants deeper PoH, because: ­ Policy of promoting infrastructure build ­ Greater competition for backhaul For discussion purposes. No implementation assurances

7. POTENTIAL HANDOVER POINTS For discussion purposes. No implementation assurances Metro Node Tier 1 MSAN Node MSAN Node CMSAN FMSAN TAMTAM Legacy MSAN Node CMSAN FMSAN TAMTAM Legacy MSAN Node CMSAN FMSAN TAMTAM Legacy CMSAN TAMTAM Legacy MSAN Node ~130 Sites ~1500 Sites ~4500 Sites ~5500 Sites P Router CORE DWDM 4/4/3 SDXC Core Node ~10 Sites ~ Voice/P C PE P Router CORE DWDM 4/4/3 SDXC Legacy switch function s Voice Intra Metro Ethernet Network Edge WDM Ethernet PE BRAS CMSAN Edge WDM FMSAN TAMTAM Lega cy ~ Voice/P C PE P Router CORE DWDM 4/4/3 SDXC Legacy switch function s Voice Intra Metro Ethernet Network Edge WDM Ethernet PE BRAS Tier 1 MSAN Node CMSAN Edge WDM FMSAN TAMTAM Lega cy CMSAN TAMTAM Legacy

8. CURRENT BT THINKING ON PoH Converged PoH as a new NGN product ­ Independent of service-specific conveyance riding on top of PoH ­ Dimensioning starting at STM-1 for SDH or Gig-E ­ Monthly port-based pricing with distance charge if circuit leased from BT Handover Points ­ Tier 1 MSANs co-located at Metro nodes ­ For operators with existing fibre, PoH at customer side of nearest Tier 1 MSAN ­ For LLU operators, PoH at nearest Tier 1 MSAN For discussion purposes. No implementation assurances

9. SERVICE LEVEL CONVEYANCE Multiple services will co-exist on PoH ­ Services may require specific network elements ­ Commercials will be different for different services Highest priority is PSTN replication ­ Needs both media routing and session control ­ Pricing will be determined by regulator Industry innovation will require new services ­ E.g. Multimedia, circuit emulation & bitstream evolution ­ For some, pricing will be commercially negotiated For discussion purposes. No implementation assurances

10. SERVICE CONVEYANCE PROTOCOLS C7 PSTN REPLICATIONMULTIMEDIAATMNGN PPC For discussion purposes. No implementation assurances Note: ATM and Circuit Emulation over Ethernet subject to further standards work.

11. STANDARDS CHALLENGES Many fora developing open standards BT committed to NICC/TSG process Sourcing standards for consideration from: ­ IETF, TISPAN, Metro Ethernet Forum, 3GPP, etc. But, localised variants cost time and money ­ Balance between backward compatibility and the burden of forever carrying the past For discussion purposes. No implementation assurances

12. SIP-I CONDUNDRUM AS EXAMPLE ITU ratified Q1912.5 for Global ISUP in SIP ETSI Plenary in September; expected to have ratified European normalised standard in December. UK NICC must agree and ratify the UK specific variations and options to ETSI SIP-I Vendors will need to support multiple SIP-I variants on a global basis: Will we back to the IUP problem in N years? For discussion purposes. No implementation assurances

13. CURRENT BT THINKING ON NGN NARROWBAND CALL CONTROL Altnet ability for full call control of their customer’s individual baseband voice line from their call server Altnet assumption was that this required physical interconnect to MSAN line card H.248 gateway Mutual learning from Consult21 Engagement Proposed BT solution enables NGN CPS and WLR for all wholesale customers ­ Provides full call control to those who invest in Call Servers ­ Not limited to deep infrastructure players ­ Promotes competition and innovative feature discrimination For discussion purposes. No implementation assurances

14. ILLUSTRATION OF AGCF SOLUTION MSAN H.248 control of line card ALTNET 1 BT ALTNET 2 Call Server AGCF “H.248 Proxy” SIP Equivalence Demarcation SIP Call Server SIP-I For discussion purposes. No implementation assurances

15. CURRENT BT THINKING ON 21CN NARROWBAND CONVEYANCE Ofcom will determine PSTN conveyance rates ­ “Technology Neutral” NCC currently in consultation ­ Market review will follow to set 21CN specific conveyance rates Industry needs commercial certainty during 4 year interregnum when 2 PSTN networks overlap ­ Non-congruent PSTN conveyance rates will be disastrous for all ­ Creating new arbitrage markets; hurting sustainable competition New Wave voice products that do not rely on C7 and PATS will follow commercial pricing models ­ No SMP nor bottleneck ­ Where all operators will try to innovate for new revenue For discussion purposes. No implementation assurances