Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change. 1 Forward Looking Statements – Caution Advised Certain statements in this presentation are forward-looking and are made in reliance on the safe harbour provisions of the US Private Securities Litigation Reform Act of These statements include, without limitation, those concerning: BT's plans for transformation of its networks; benefits to customers of the 21CN programme; key milestones and expected timetable for delivery of 21CN; and the benefits in relation to, for example interconnect, convergence and broadband. Although BT believes that the expectations reflected in these forward-looking statements are reasonable, it can give no assurance that these expectations will prove to have been correct. Because these statements involve risks and uncertainties, actual outcomes may differ materially from those expressed or implied by these forward-looking statements. Factors that could cause differences between actual outcomes and those implied by the forward-looking statements include, but are not limited to: material adverse changes in economic and financial markets conditions in the markets served by BT; supplier arrangements; future regulatory actions and conditions in BT’s operating areas; technological innovations; developments in the convergence of technologies and the anticipated benefits and advantages of new technologies, products and services, including broadband, not being realised.

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change. 2 Migration Provisioning: Interconnect Routes – DLE to NGS Ron Riches The purpose of this presentation is to outline to Communications Providers BT’s view of:  How BT will manage the allocation of slots for route migration  Fallback for DLE to NGS migration

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change. 3 Interconnect Route Migration: Transfer Slot Allocation The purpose of this presentation is to show the concept of : how Interconnect Migration Transfer Slots will be progressed forwards from the issue of the High Level SAN how Interconnect Migration Transfer Slots will be allocated and managed on a CP basis within each month

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change. 4 BT DLE L/XXX/UC CP 'A' SWITCH 1 YY/AAA/1 CP 'A' SWITCH 2 ZZ/AAA/2 route 1 route 2 route 3 BT NGS L/ABC In this example : CP 'A' has 3 routes to the closing BT DLE from 2 switches in their network CP Interconnect architecture pre-migration

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change. 5 BT DLE L/XXX/UC CP 'A' SWITCH 1 YY/AAA/1 CP 'A' SWITCH 2 ZZ/AAA/2 route 1 route 2 route 3 BT NGS L/ABC transfers to take place at a pre agreed date and time CP 'A' now has 3 routes to the target NGS from 2 switches in their network CP Interconnect architecture post-migration

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change. 6 Tranche X M1 (-6)M2 (-5)M3 (-4)M4 (-3)M5 (-2)M6 (-1)DLE C/O M1 (-6)M2 (-5)M3 (-4)M4 (-3)M5 (-2)M6 (-1) M1 (-6)M2 (-5)M3 (-4)M4 (-3)M5 (-2)M6 (-1) Tranche Y M1 (-6)M2 (-5)M3 (-4) M1 (-6)M2 (-5)M3 (-4) M1 (-6)M2 (-5)M3 (-4) M1 (-6) M2 (-5) M3 (-4) M4 (-3) M5 (-2) M6 (-1) DLE C/O DLE To NGS Transfer Months Stability Months Freeze Month DLE to MSAN transfer Month M4 (-3)M5 (-2)M6 (-1) M4 (-3)M5 (-2) M4 (-3) Administration & Preparation Phases Admin PhasePreparation PhaseTransfer PhaseStability PhaseNetwork FreezeDLE To MSAN CP Interconnect Migration Timeline Phases In the SAN Tranche programme Transfer Phases will overlap It is important to aim to achieve the DLE to NGS CP migrations in 'M1' of each DLE to MSAN's timeline - else a build up of work will occur CP Interconnect route migration schedule

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change. 7 Administration PhasePreparation PhaseTransfer Phase RFT # Achieved # RFTs (Ready For Test) will be achieved throughout the Preparation Phase Transfer Date RFTs, on a per route basis, will be notified weekly to CPs by will contain the Transfer Date within the Transfer Phase - positive response required HLSAN (3 month transfer window) ACOsOrders DSAN (1 week transfer window) Negotiations Admin PhasePreparation PhaseTransfer PhaseStability PhaseNetwork FreezeDLE To MSAN CP Interconnect Migration Timeline Phases CP Interconnect route migration - detail

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change. 8 W1W2W3W4W5W6W7W8W9W10W11WN Tranche X D1D2D3D4D5 S1 S2 S3 S4 S5 S6 SN each week HLSAN DSAN At Route RFT Achieved M1 (-6)M2 (-5)M3 (-4) 1 slot = 0700 to Monday to Friday 1 slot = one (minimum) ITO 1 slot = 1 DLE to 1 CP Switch 6 slots gives ~ 5 x 4 x 3 = slot gives ~ 5 x 4 x 3 = 60 each extra slot gives ~ month transfer window given & agreed 1 week transfer window given & agreed W1W2W3W4 M1 (-6) W1W2W3W4 M1 (-6) W5W6W7W8 M2 (-5) actual slot date given & agreed Pre Transfer actual time agreed + 2, non pre allocated, 'mop up' slots gives ~ the total number of working days will vary for each Tranche Admin Phase Prep Phase CP Interconnect route transfer slot allocation

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change. 9 BT DLE L/XXX/UC CP A SWITCH 1 YY/AAA/1 CP A SWITCH 2 ZZ/AAA/2 route 1 route 2 route 3 Slot 1 Slot 2 could use the same signalling link(s) BT NGS L/ABC In this example : CP 'A' has 3 routes to the closing BT DLE from 2 switches in their network CP Interconnect architecture pre-migration: Transfer slot allocation detail

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change. 10 Example Allocation Requires 22 slotsCP 1 Requires 15 slotsCP 2 Requires 12 slotsCP 3 Requires 7 slotsCP 4 Requires 7 slotsCP 5 Requires 5 slotsCP 6 Requires 4 slotsCP 7 Requires 4 slotsCP 8 Requires 1 slotsCP 9 Requires 1 slotsCP 10 W 1 W 2W 3W 4 'mop-up' slots Variable number of DLEs and variable number of impacted CP Routes per migration Tranche Variable number of slots required per CP per Tranche Variable number of slots available per Tranche Slots will be allocated from the beginning of the month starting with CP who has the greatest requirement that month DLEs are then mapped over slots 15 rules developed to achieve best fit allocations per month CP Transfer Slot Allocation – BT approach

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change CN CP Interconnect Migration : DLE To NGS High Level Fallback The purpose of this presentation is to show the concept of how, at a high level, DLE to NGS Fallback, if required, will be jointly managed and progressed by BT and the impacted CP.

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change CN CP Interconnect Migration: High Level Failures (DLE To NGS ) Administration PhasePreparation PhaseTransfer Phase Failure Re-programme Transfer eg - in same Transfer Phase Fallback Management Escalation eg - disparity process Failure Admin PhasePreparation PhaseTransfer PhaseStability PhaseNetwork FreezeDLE To MSAN CP Interconnect Migration Timeline Phases

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change CN CP Interconnect Migration: High Level Fallback (DLE To NGS) Key points in the Transfer Phase where Fallback could be triggered: After the existing E1s at the DLE have been placed 'Out Of Service' As new, or re-arranged, E1s at the NGS are 'Brought Into Service' or 'Returned To Service' After new, or re-arranged, E1s at the NGS have been 'Brought Into Service' or 'Returned To Service' Approach to Fallback: any decision to fallback will be taken jointly between BT and the CP involved in the transfer the decision will be based on the individual route and failure circumstances

Consult21 Information is subject to change and is for discussion purposes only. Any dates/timings are the current anticipated timescales and may be subject to change CN CP Interconnect Migration : High Level Fallback Model (DLE to NGS) Continue With Transfer Transfer Failure Occurs Investigate Transfer Failure Fix ? Y Instigate Fallback Review Reasons For Fallback N Organise Failure Fix & Arrange New Date Fallback Successful Fallback Un- Successful Fallback Required ? N Y Fix Fallback any decision to fallback will be taken jointly between BT and the CP involved