#1ADURAN ADVA Transformative Combination Creating a New Global Leader August 30, 2021#2#3Safe Harbor / Disclaimers ADURAN ADVA™ Non-GAAP Financial Measures In this presentation, in addition to GAAP financial results, ADTRAN and ADVA have provided non-GAAP financial measures including non-GAAP Gross Profit, adjusted EBITDA, and Free Cash Flow. These non-GAAP financial measures are provided to enhance the user's understanding of our past financial performance and our prospects for the future. Our management team uses these non-GAAP financial measures in assessing ADTRAN's performance, as well as in planning and forecasting future periods. These non-GAAP financial measures are not computed according to GAAP and the methods we use to compute them may differ from the methods used by other companies. Non-GAAP financial measures are supplemental, should not be considered a substitute for financial information presented in accordance with GAAP and should be read only in conjunction with ADTRAN's consolidated financial statements prepared in accordance with GAAP. These non-GAAP financial measures references are reconciled to their most directly comparable GAAP financial measures in the Appendix at the end of this presentation. Important Information for Investors and Stockholders This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. It does not constitute a prospectus or prospectus equivalent document. No offering of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the U.S. Securities Act of 1933, as amended. In connection with the proposed transaction between ADTRAN and ADVA, Acorn HoldCo is expected to file a Registration Statement on Form S-4 with the U.S. Securities and Exchange Commission ("SEC") that will include (1) a proxy statement of ADTRAN that will also constitute a prospectus for Acorn HoldCo and (2) an offering prospectus of Acorn HoldCo to be used in connection with Acorn HoldCo's offer to acquire ADVA shares held by U.S. holders. When available, ADTRAN will mail the proxy statement/prospectus to its stockholders in connection with the vote to approve the merger of ADTRAN and an indirect wholly-owned subsidiary of Acorn HoldCo, and Acorn HoldCo will distribute the offering prospectus to ADVA shareholders in the United States in connection with Acorn HoldCo's offer to acquire all of the outstanding shares of ADVA. Acorn HoldCo is also expected to file an offer document with the German Federal Financial Supervisory Authority (Bundesanstalt fuer Finanzdienstleistungsaufsicht) ("BaFin"). INVESTORS AND SECURITY HOLDERS OF ADTRAN AND ADVA ARE URGED TO READ THE PROXY STATEMENT/PROSPECTUS, THE OFFER DOCUMENT AND OTHER DOCUMENTS THAT WILL BE FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION. Investors and security holders will be able to obtain free copies of the proxy statement/prospectus (when available) and other documents filed with the SEC by ADTRAN or Acorn HoldCo through the website maintained by the SEC at http://www.sec.gov. Copies of the documents filed with the SEC by ADTRAN will be available free of charge at https://investors.adtran.com/ and under the heading "SEC Filings". Furthermore, the German language version of the offer document will be published by way of announcement on the internet at www.acorn-offer.com and by keeping available copies free of charge at the settlement agent. You will also be able to obtain a copy of the non-binding English translation of the offer document, which has not been reviewed by BaFin, on the internet at www.acorn-offer.com. 3 Certain Information Regarding Participants ADTRAN, ADVA, Acorn HoldCo and their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from ADTRAN's stockholders in respect of the proposed business combination. Information regarding the persons who are, under the rules of the SEC, participants in the solicitation of the stockholders of ADTRAN in connection with the proposed transaction, including a description of their direct or indirect interests, by security holdings or otherwise, will be set forth in the proxy statement/prospectus to be filed with the SEC. Information regarding the directors and executive officers of ADTRAN is contained in ADTRAN's Annual Report on Form 10-K for the year ended December 31, 2020 and its Proxy Statement on Schedule 14A, dated March 30, 2021, which are filed with the SEC and can be obtained free of charge from the sources indicated above. Other information regarding the participants in the proxy solicitations and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the proxy statement/prospectus and other relevant materials to be filed with the SEC regarding the proposed transaction when they become available.#4Today's Presenters 4 Tom Stanton Chairman & CEO ADURAN Brian Protiva CEO ADVA™ Mike Foliano CFO ADURAN ADURAN ADVA™ Uli Dopfer CFO ADVA#5Transformative Combination of ADTRAN and ADVA Creates a Global Leader 5 Creating a leader in end-to-end fiber networking (from metro core to customer premises) ADURAN + A leading global provider of fiber access, fiber extension and cloud-managed subscriber connectivity solutions $7.1B Combined Addressable Market Opportunity(¹) $1.2B Combined LTM Revenue(2) ADURAN ADVA™ ADVA™ A leading global provider of metro WDM, data center interconnect, business ethernet, and network synchronization solutions $183M Combined LTM EBITDA(2)(3) $52M Anticipated Run Rate Synergies By Year 2 post-closing(4) Note: Figures are non-GAAP. (1) Combined addressable market opportunity inclusive of Metro WDM & Business Ethernet and Passive Optical Networking for North America and EMEA. (2) LTM period is for the twelve months ending June 30, 2021. ADVA financials converted to USD from EUR at an exchange rate of 1.1929, the average exchange rate for the twelve months ending June 30, 2021. (3) Inclusive of $52 million annual run-rate pre-tax synergies. Please see appendix slides for Non-GAAP reconciliations. (4) Represents annual run-rate pre-tax synergies.#6#7#8#9#10#11#12#13#14#15#16#17#18#19#20