Level 3 Voice Services Network Architecture June 15, 2004 11/8/2018 1

About Level(3) Communications Network 19,000 mile North American intercity network 72 North American markets in service 3,600 mile Pan European network 20 European markets in service Fully owned Trans-Atlantic undersea capacity via Yellow MPLS used to manage QoS from end to end Softswitch Operating Experience Developing and operating Softswitch platforms since 1998 Running VoIP since 1999 100% Softswitch infrastructure for VoIP and Dial traffic CLEC-based services in 48 states with 1.8 million trunks Rate center coverage to 93% of the U.S. population More than 24 Billion minutes of Softswitch traffic per month Over 300 Billion lifetime Softswitch minutes 11/8/2018

Services & Revenue Breakdown Softswitch Services – 42% of Communications Revenue(1) Managed Modem Voice Services IP & Data Services – 26% of Communications Revenue(1) Dedicated Internet Access (3)FlexSM Data Services Security & VPN DSL Aggregation Transport & Infrastructure Services – 32% of Communications Revenue(1) Wavelengths Private Line Transatlantic & Backhaul Fiber Services Gateway Services Colocation Fiber Services Technical Support (1) Percentages are based on first quarter 2004 Communications GAAP revenue 11/8/2018

Softswitch Background VIPER softswitch Developed in-house and supported by internal developers Patented in August 2002 Incremental capacity can be added at a fraction of the cost of circuit-switched solutions Co-carrier trunk plant National network of direct interconnects to all major LECs Operational experience Created the OSS and processes to manage large volume of traffic at significantly lower costs than legacy providers Ability to extend platform to other services Continuing to invest in platform Ability to offer additional services using same infrastructure 11/8/2018

Level 3 – Softswitch Network Coverage Softswitch Local Footprint CLEC-based service in 48 states with 1.4 million trunks and full Local Number Portability (LNP) compliance Rate centers cover approximately 93% of the U.S. population Sample coverage – Kansas City 13 rate centers 14,400 trunks installed Long-distance Footprint 240 IXC tandem interconnects Wholesale termination of voice calls into Country code 1 (U.S., Canada, and U.S. Territories) and internationally. 11/8/2018

Level 3 Voice Services Overview 11/8/2018

Voice Services Portfolio Level 3 Products Product Type Segment Target Enterprise 3Tone Value Added Hosted (Turn-Key Applications) Consumer HomeTone Enhanced (Class 5 Functionality) Consumer or Enhanced Local Enterprise Transport ( Building Blocks) Local Inbound Toll Free Transit/Peering Termination Wholesale Level 3 provides a vertically integrated suite of VoIP products which allows customers to choose the amount of product complexity they want to manage 11/8/2018

Voice Services Portfolio Level 3 Products Product Type Capabilities HomeTone + Business Features = 3Tone Value Added Hosted (Turn-Key Applications) Enhanced + Hosted Application = HomeTone Transport + E911, Class 5 Enhanced (Class 5 Functionality) = Enhanced Local Enhanced Local Origination & Termination Transport ( Building Blocks) Local Inbound Toll Free Transit/Peering Termination = Level 3 provides a vertically integrated suite of VoIP products which allows customers to choose the amount of product complexity they want to manage 11/8/2018

Level 3 Voice Architecture 11/8/2018

IP and PSTN Interfaces Signaling Gateway IP Media Gateway Takes external signaling in both traditional TDM and IP mechanisms and normalizes them to SIP for use in the Level 3 Network. IP Media Gateway Media Interworking and border control of the Level3 IP Network; provides security, NATing, topology hiding etc. TDM Media Gateway Media Interworking function between the TDM/PSTN network and the IP Network. 11/8/2018

Network Features Session Controller Network & Feature Servers This device establishes and controls sessions in the network. It maintains state and controls gateways Network & Feature Servers Receives SIP signaling and applies routing or feature services Media Servers End points used by Feature Servers to manipulate or send media (announcements, conferences, etc). 11/8/2018

3Voice Termination (IP Handoff) Logical Architecture 11/8/2018

3VoIP Local Inbound Logical Architecture 11/8/2018

3VoIP Enhanced Local Logical Architecture Inbound Architecture works like 3VoIP Inbound Local Outbound Architecture works like 3VT(IP) with End Office Termination 11/8/2018

HomeTone Logical Architecture 11/8/2018

Regulatory Environment Level 3 is a certified telecommunications service provider at the federal and state levels Registered as a CLEC in all states except Iowa and Maine Supports E911, Operator/ Directory Services, LNP, N11, etc Forbearance petition filed in January 2004 Asks FCC to reaffirm that legacy switched access charges to not apply to voice over IP 11/8/2018