Enabling the Future Network

ADTRAN at a Glance Broad Portfolio of Solutions More than 1,700 products 2011 Revenues - $717 million Carrier Division - $569 million Enterprise Division - $148 million Strong Financials Over 20 years of continuous profitability 1,750 Employees Global Presence Headquartered in Huntsville, AL Development centers: Phoenix, AZ Ottawa, Canada Mountain View, CA Hyderabad, India Boston, MA NSN BBA Acquisition ADTRAN Headquarters, Huntsville, AL NASDAQ: ADTN 2 2

Global Market Trends Broadband / Ethernet Access Mobility Exponential growth in bandwidth access IP traffic will increase 4x over next five years VoIP proven and continues significant growth Mobility Mobile data demand growing 15-25x over next three years Users have growing number of end-points 3 to 5 devices per person Smartphone, iPad, laptop, machine-to-machine Cloud Services & Applications Shift to cloud computing drives demand for Enterprise and SMB connectivity Virtualization Applications running on virtual machines increase efficiency, reduce space and carbon footprint 3

New Devices and Applications New Mobile Devices iPad, tablets, smart phones, etc.. New Applications Video, gaming, etc.. Cloud services Voice over Wi-Fi Major Usage Changes Netflix is now 30% of Internet traffic Over 50% of the 800M Facebook users are active daily Over 350M users access Facebook on their mobile device Two-way video chat Skype Apple’s Facetime

Mobility Demand is Exploding 5B Mobile Phones Globally Smart phones are Pervasive True Mobility is no Longer a Convenience Voice over Wi-Fi, Facetime New Devices Rely on Wireless Connectivity iPads Mobile Data Traffic is Growing Exponentially Wi-Fi Data Offload to Fixed Network is Necessary Source: FCC

Cloud is the Future Cloud services level the playing field for businesses of all sizes and deliver global scalability IDC estimates the market for public cloud products and services will grow to $56 billion by 2014 Amazon’s S3 Cloud Storage Service skyrocketed from 262 billion in 2010 to over 566 billion in 2011 Over 370,000 requests per second Small business public cloud computing spending is estimated to reach $6 billion by 2014 (Source: In-Stat - December 2010)

ADTRAN Areas of Focus Broadest Portfolio of Broadband Solutions Fiber-to-the-Home/Node/Curb, Ultra Broadband Mobile Infrastructure Fixed access from exchange to cell tower Optical access, Carrier Ethernet access, Broadband access Cloud Connectivity Enterprise converged access Hosted service provider solutions Carrier Ethernet, broadband connectivity Virtualization enables unlimited scalability Broadband Mobility Cloud

ADTRAN – Complete Connectivity Exchange Provider’s Access Infrastructure Business & Residential Customers 8

ADTRAN – Complete Connectivity Broadband Access Industry’s most widely adopted access platform Ethernet Aggregation Cost-effective for high-density Ethernet deployment Optical Access Specifically designed for the access edge Redefining the packet optical edge Exchange 9

ADTRAN – Complete Connectivity Mobile Backhaul Efficient fiber Ethernet services Business Ethernet Services Full range of service rates and service reach Business Service Migration Extend product lifecycle Provider’s Access Infrastructure 10

ADTRAN – Complete Connectivity Cloud Connectivity Industry leadership in service provider bundles Enterprise Communications Solutions which enable businesses to become more capable and efficient Virtual Mobility Complete end-point freedom throughout the Enterprise Residential Deliver Ultra Broadband for premium services Business & Residential Customers 11

Core Product Performance 48% growth 65% growth 36% growth 25%growth ADTRAN Core Products Solid performance in Core Products Broadband Access Optical Access Internetworking

Broadband Access Opportunity Market Characteristics Carrier consolidation Releases investment Competitive push by non-wireless carriers Government mandates US Other regions Over the top video Continual bandwidth upgrades The demand for availability and greater capacity Broadband connectivity is pervasive across the globe. Carrier consolidation has release significant CapEx investment for networks that had previously been under invested as well to meet State PUC and FCC merger obligations. Examples include Frontier’s acquisition of 5M lines from Verizon and CenturyLink’s acquisition of Qwest. We also see strong market competition from fixed line carriers, cable and wireless carriers to deliver greater speed and availability. Countries around the world have implemented National Broadband Plans and aspirational speed and broadband availability targets to increase global competitiveness and for economic development. In the U.S., the government launched a $7.2B Broadband Stimulus program that is just starting to result in CapEx spending. The FCC also implemented a National Broadband Plan with the goal of delivering 100Mbps to 100M households by 2020. As part of the National Broadband Plan, the FCC issued an Order in late 2011 to reform the voice-based $4.5B/yr Universal Service Fund (high cost fund) to be targeted to broadband, which will also fuel CapEx investment for broadband infrastructure. End-user demand and high capacity applications continue to drive continuous upgrades for greater availability and more bandwidth capacity. According to Infonetics, ADTRAN is the market leader in the U.S. in MSAP (Multi-Service Access Platforms (TA 5000)) and in DSL. ADTRAN also experienced 500% growth in Fiber To The Home deployments in 2011. ADTRAN has one of the industry’s broadest portfolios of broadband access solutions which include our highly differentiated Ultra Broadband solutions. ADTRAN’s Ultra Broadband solutions deliver deep fiber to sealed and maintenance-free Outside Plant nodes that cost effectively deliver ultra-high broadband performance for the delivery of premium internet and high-bandwidth video services. Ultra Broadband Premium internet and video to more customers at the lowest TCO Fiber to the Home Ultra flexible, high capacity deep fiber solutions

Core Product Growth – Broadband Access Proven market share growth (2007-11) #1 DSL & MSAP in NA #3 DSL Globally #4 MSAP Globally Increasing demand for premium internet, video delivery and business services Leveraging healthy forecast for high-speed services globally Source is Infonetics report called “2011-Infonetics-3Q11-PON-FTTH-DSL-Mkt-Fcst-Updated-12-13-11” In the latest reported marketshare (3Q11), ADTRAN has moved into the #1 marketshare leader for DSL and MSAP (Multi-Service Access Platforms) according to Infonetics Research. ADTRAN also hold the #3 global position in DSL and the #4 global position in MSAPs Source: Infonetics

Internetworking Opportunity Market Characteristics Cloud Connectivity Market Leadership in public and private cloud connectivity Rise of Cloud Services Public & Private More Communications Enabled Business Processes Unified Communications Explosion of Mobile Devices End-user (not IT) dictates the device Demand for bandwidth Enterprise Communications Premises-based solutions enabling business productivity Businesses around the world are rapidly moving to public and private Cloud-based services. ADTRAN is the market leader in Cloud Connectivity. In the U.S., ADTRAN cloud connectivity solutions are included in 85% of the Tier 1 Service Provider bundled business services and ADTRAN maintains 72% to 100% market share (internal estimates) in the bundles that we participate in. The follow are the Bundled Business Services that ADTRAN participates in and a list of the ADTRAN solutions included in those bundles: Bundled Business Services Hosted Centrex, Hosted UC, Hosted IP Centrex, Hosted WLAN, Business Internet Access, Business Ethernet (on ramp MPLS (IDE) and IDA), Private Network (MPLS), SIP Trunking, Managed Security, Managed UC and SIP Trunking with PBX bundle Bundled Business Service Solutions IP Business Gateways, Access Routers, Ethernet Switches, Unified Communications, Unified Threat Management In addition to market leadership in Service Provider business services, ADTRAN provides a strong offering of Enterprise Communication solutions. Businesses around the world have been forces to cut back on staff and resources putting a major demand on being able to do more with less. ADTRAN’s line of Enterprise Communications solutions are premises-based solutions that enable businesses to be more productive and more capable through communications enabled businesses processes with Unified Communications, efficient LAN infrastructure solutions and highly scable wireless LAN solutions. With the explosion of Mobile Devices such as smart phones and tablets, the end-user now is in control of device selection, the number devices simultaneously used and how the applications that are used (video, voice over WiFi, video conferencing, etc). This puts significant demand on the IT department to deliver massive wireless bandwidth, scalability for many devices per users and enable persistent IP sessions across the enterprise campus. Users demand end-point freedom across the enterprise. ADTRAN’s initial Virtual Mobility solution is the Bluesocket Virtual Wireless LAN which is the Industry’s first fully cloud-based wireless LAN solution. Virtual Mobility End point freedom across the Enterprise

Core Product Growth – Internetworking Proven market share growth (2007-11) #1 Cloud Connectivity #1 SIP Trunking #2 Access Routers Market Leadership in Carrier Bundled Business Services Highly Differentiated Virtual Wireless LAN and Unified Communications #1 Cloud Connectivity - ADTRAN is in 85% of US Tier 1 service provider bundles and maintains 72% to 100% market share (based on Svc Provider reporting to ADTRAN) Frost & Sullivan (2011) reported that ADTRAN is #1 in SIP Trunking (for Converged Access (ie IP Business Gateways)) but most of ADTRAN’s revenue is in North America. Infonectics reports that ADTRAN maintains a #2 market share position in access routers. Source: Infonetics

Optical Access Opportunity Market Characteristics Massive Traffic Growth Limitless Optical Capacity Simplified Operations Optical Ethernet 5B Mobile Devices Worldwide Computer on your hip Mobile Broadband Exponential Bandwidth Requirements Service Providers are under pressure to deliver more and more bandwidth to consumers, businesses and mobile users while simplifying their work-flow processes and network architecture. These are reflected in the mobile infrastructure upgrades and major LTE rollouts which began in 2011 and will continue through 2014. Service providers rolling out fiber-based telecom networks for mobile broadband need solutions that can adapt quickly to not only this near-term opportunity but as well to emerging customer demands from business services delivery and broadband services backhaul which will require optical access and aggregation. In 2011, ADTRAN moved from Optical Access to Optical Networking with the launch of the Optical Networking Edge (ONE) in response to the massive traffic growth at the edge of the network. New functionality such as ROADM (reconfigurable Add / Drop multiplexer) and OTN (Optical Transport Network) were introduced from the Total Access 5000 in order to reduce network complexity using Packet Optical, blurring the boundaries between access aggregation and transport. ONE is unique because it right-sizes Packet Optical technology to operate at the edge of the network – removing bandwidth bottlenecks, reducing network complexity to accelerate services revenue. ADTRAN provides a full portfolio of Optical Access solutions that includes Opti-6100 SONET/SDH MSPP (service provisioning platform), the Total Access 5000-based Optical Ethernet access and aggregation components, QDFR (quad fiber) T1 services over fiber and the NetVanta 8044M Cell site Gateway. Optical Networking Edge Right-sizing Packet Optical to reduce complexity at the network edge. Mobile Backhaul Enabling the promise of Mobile Broadband

Core Product Growth – Optical Access Expanding Optical Addressable Market SONET  WDM Access & Transport U.S.  Global Growing Market Share Highly Differentiated Solutions - ONE Reducing Network Complexity Accelerating Services Delivery Pull-Thru Revenue ONE differentiation pulls through sales in Broadband Access Source is Infonetics report called “2011-Infonetics-3Q11-PON-FTTH-DSL-Mkt-Fcst-Updated-12-13-11” ADTRAN is expanding its Optical Addressable Market with the introduction of the Optical Networking Edge (ONE) solution that was introduced in 2011. The solution “right sizes” Packet Optical technology to address the bottle necks of Access Aggregation. ADTRAN’s Optical Addressable market now goes beyond SONET Optical Access addressed by the OPTI-6100 with the ONE solutions, addressing Packet Optical at the access edge. In addition to addressing WDM, ADTRAN expands beyond just Access to also include Optical Transport. The ONE also enables ADTRAN’s Addressable Market to expand beyond the U.S. (SONET market) to include the Global Packet Optical market. The ONE solution also provides significant access aggregation differentiation for our TA 5000 for Broadband Access deployments, pulling through incremental Broadband Access revenue. Source: Infonetics

International Growth Progress 2011 Revenue Contribution International International Growth Domestic 165% Growth 215% Growth 2010 2011 2010 2011 Q4 2011 over Q4 2010

Planned Acquisition of NSN’s BBA Business ADTRAN announced that it plans to acquire Nokia Siemens Networks Broadband Access (BBA) business NSN BBA business includes MSAN, GPON, DSLAM and related Network Management Solutions and associated IPR Incumbent customer base of carriers across >20 countries in Europe, Middle East, Africa, India, Russia and Asia Strong team of sales, service, support, and engineering Acquisition is anticipated to close by the end of April 2012 Advances ADTRAN’s Top Tier Global Supplier status in fixed broadband access EPS neutral for first full year, accretive thereafter

Purpose of Acquisition Accelerates strategic plan for global growth Incumbent supplier to top Carriers across the globe, including DT, Bezeq, Sunrise and others Regional Diversity Complementary product portfolios Strong global MSAN Solutions ADTRAN adds Carrier Ethernet, Ethernet Business Services, Mobile Backhaul, Enterprise solutions… NSN BBA adds MPLS, H.248, ETSI voice, global services… Combined portfolios deliver compelling global roadmap Strengthens Engineering and Services resources to focus on global accounts Provides word-class sales, services and customer support

ADTRAN Customer Focus EUROPE NORTH AMERICA ASIA AFRICA SOUTH AMERICA AUSTRALIA ANTARCTICA

NSN BBA Customer Focus EUROPE NORTH AMERICA ASIA AFRICA SOUTH AMERICA AUSTRALIA ANTARCTICA

Combined Customer Focus EUROPE NORTH AMERICA ASIA AFRICA SOUTH AMERICA AUSTRALIA ANTARCTICA

Top Tier Global MSAP Ranking – Ports Global – MSAP Category (Port Shipments) Source: Infonetics Q3 2011 Report

Top Tier Global DSL Ranking – Revenue Global – DSL Category (Revenue) Source: Infonetics Q3 2011 Report

Annual Revenue and EPS EPS: 2007-2011

Return on Invested Capital and Economic Value Added Spread (trailing twelve months) *Adjusted for nonrecurring tax items. Information derived from Bloomberg as of January 1, 2012

Highly Differentiated Solutions That Deliver Immediate Business Results Large Growth Markets Strong Company Solid Performance Global Presence 29