Amendment: SEC Form SCHEDULE 13D/A filed by Telephone and Data Systems Inc.

The principal business and office address of TDS, is 30 North LaSalle Street, Suite 4000, Chicago, Illinois 60602. The information with respect to the directors and executive officers of TDS is set forth on Appendices A and B attached hereto, and incorporated herein by reference. The principal business address of the Voting Trust is c/o TDS, 30 North LaSalle Street, Suite 4000, Chicago, Illinois 60602. The information with respect to the trustees of the Voting Trust is set forth in Appendix C hereto, and incorporated herein by reference.

TDS' principal business is that of providing high-quality communications services. The Voting Trust holds common shares, par value $0.01 per share, of TDS ("TDS Common Shares"), and series A common shares, par value $0.01 per share, of TDS ("TDS Series A Common Shares"), that are which are convertible on a share-for-share basis into TDS Common Shares, and was created to facilitate long-standing relationships among the trust's certificate holders. Under the terms of the Voting Trust, the trustees hold and vote the TDS Series A Common Shares and TDS Common Shares held in the trust. The information with respect to the directors and executive officers of TDS is set forth on Appendices A and B attached hereto, and incorporated herein by reference. The information with respect to the trustees of the Voting Trust is set forth in Appendix C hereto, and incorporated herein by reference.

To the knowledge of Walter C. D. Carlson, during the last five years, none of TDS, any of the persons named in Appendices A and B hereto, the Voting Trust nor any of the persons named in Appendix C hereto has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

To the knowledge of Walter C. D. Carlson, during the last five years, none of TDS, any of the persons named in Appendices A and B hereto, the Voting Trust nor any of the persons named in Appendix C hereto was a party to a civil proceeding of a judicial or administrative body of competent jurisdiction, and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

TDS is a Delaware corporation. The Voting Trust is organized under Delaware law. The information with respect to the directors and executive officers of TDS is set forth on Appendices A and B attached hereto, and incorporated herein by reference. The information with respect to the trustees of the Voting Trust is set forth in Appendix C hereto, and incorporated herein by reference.

This Amendment Number 21 to Schedule 13D is filed to reflect that the sale of the Issuer's wireless operations and select spectrum assets to T-Mobile US, Inc., as announced in Amendment No. 19, was completed on August 1, 2025. The information contained in Item 4 below is incorporated herein by reference.

This Item 4 is being updated by the following information. On August 1, 2025, the Issuer completed the sale of its wireless operations and select spectrum assets to T-Mobile US, Inc. for approximately $4.3 billion in cash and the assumption of certain debt, as further described in TDS' Form 8-K filed with the Securities and Exchange Commission on August 4, 2025. The trustees of the Voting Trust have advised TDS that they intend to maintain the ability to keep or dispose of the voting control of TDS. The trustees of the Voting Trust have further advised TDS that, if and to the extent that the Issuer remains a publicly-traded company, the trustees of the Voting Trust intend that TDS maintain the ability to keep or dispose of the voting control of the Issuer. TDS and the trustees of the Voting Trust also retain the right to change their intent, to acquire additional securities from time to time or to dispose of all or part of the securities beneficially owned by TDS or the Voting Trust in any manner permitted by the terms of the Voting Trust and/or applicable law. Except as disclosed or incorporated by reference herein, TDS and the Voting Trust do not have any current intention, plan or proposal with respect to any of the matters specified in paragraphs (a) through (j) of Item 4 of Schedule 13D.

As of the date of this Amendment Number 21 to the Schedule 13D, TDS may be deemed to beneficially own, pursuant to Rule 13d-3(d)(1)(i), an aggregate of 37,782,826 Common Shares which is approximately 70.8% of such shares outstanding. In addition, TDS owns 33,005,877 Series A Common Shares which have ten votes per share on all matters and are convertible on share-for-basis into Common Shares. The information with respect to the directors and executive officers of TDS is set forth on Appendix D attached hereto, and incorporated herein by reference. As of the date of this Amendment Number 21 to the Schedule 13D, pursuant to Rule 13d-3(d)(1)(i), the Voting Trust may be deemed to beneficially own an aggregate of 37,782,826 Common Shares representing 70.8% of such shares. In addition, the Voting Trust may be deemed to beneficially own 33,005,877 Series A Common Shares.

(I) TDS. (i) Sole Power to Vote or Direct the Vote: TDS is the direct beneficial owner of 37,782,826 Common Shares and 33,005,877 Series A Common Shares of the Issuer representing approximately 82.0% of all classes of common shares of the Issuer. The Series A Common Shares have ten votes per share on all matters and are convertible on a share-for-share basis into Common Shares. TDS has sole voting power with respect to an aggregate of 37,782,826 Common Shares and 33,005,877 Series A Common Shares representing approximately 95.9% of the combined voting power of the Common Shares and the Series A Common Shares. As a result of such ownership, TDS has the voting power to elect all of the directors of the Issuer. (ii) Shared Power to Vote or Direct the Vote: None. (iii) Sole Power to Dispose or Direct the Disposition: TDS has sole power to dispose of 37,782,826 Common Shares and 33,005,877 Series A Common Shares, representing approximately 82.0% of all classes of capital stock outstanding. (iv) Shared Power to Dispose or Direct the Disposition: None. (II) Directors and Executive Officers of TDS. The information with respect to the directors and executive officers of TDS is set forth on Appendix D attached hereto, and incorporated herein by reference. (III) The Voting Trust. (i) Sole Power to Vote or Direct the Vote: None. (ii) Shared Power to Vote or Direct the Vote: The Voting Trust is the direct beneficial owner of TDS Series A Common Shares and TDS Common Shares. The Voting Trust holds and the trustees vote 7,210,499 TDS Series A Common Shares and 6,301,814 TDS Common Shares, representing approximately 95.6% of the outstanding TDS Series A Common Shares and approximately 5.8% of the outstanding TDS Common Shares, and approximately 56.8% of the combined voting power of all outstanding shares of TDS capital stock with respect to matters other than the election of directors (based on 108,232,402 TDS Common Shares and 7,538,781 TDS Series A Common Shares on August 1, 2025). Therefore, the Voting Trust may direct a majority of the combined voting power of TDS, which has voting power to elect all directors of the Issuer and has approximately 56.8% of the combined voting power of the Issuer with respect to matters other than the election of directors. (iii) Sole Power to Dispose or Direct the Disposition: None. (iv) Shared Power to Dispose or Direct the Disposition: The information contained in Item 5.III(b)(ii) above is incorporated herein by reference. Through the ability to direct a majority of the combined voting power of TDS, the Voting Trust trustees share the power to direct the disposition of 37,782,826 Common Shares and 33,005,877 Series A Common Shares of the Issuer, representing approximately 82.0% of all classes of capital stock outstanding of the Issuer.

Except as disclosed below, to the knowledge of Walter C. D. Carlson, no transactions were effected during the past sixty days in Common Shares by TDS, by any Director or Executive Officer of TDS, or by the Voting Trust except to the extent disclosed herein, and as may be attributable to TDS pursuant to transactions in the ordinary course under employee benefit plans. Walter C. D. Carlson was awarded 1,146 Common Shares on August 1, 2025, in connection with his service as a director of the Issuer. Douglas W. Chambers had 52,654 of previously granted restricted stock units and performance share units vest on August 1, 2025 as a result of accelerated vesting triggered by the sale of the Issuer's wireless operations and select spectrum to T-Mobile, of which 24,749 were withheld to cover his taxes and he was issued 27,905 net Common Shares. Mr. Chambers had an additional 67,005 of previously granted restricted stock units and performance share units vest on August 1, 2025 as a result of accelerated vesting due to the above referenced sale of the Issuer's wireless operations and select spectrum assets, which were settled in cash at $73.50 per unit.

To the knowledge of Walter C. D. Carlson, no other person is known to have the right of dividends from, or the proceeds from the sale of the shares of Common Shares beneficially owned by TDS. To the knowledge of Walter C. D. Carlson, no person other than the persons listed in Appendix D are known to have the right to receive or the power to direct the receipt of dividends from, or other proceeds from the sale of Common Shares beneficially owned by the persons listed in Appendix D. To the knowledge of Walter C. D. Carlson, no person other than TDS is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, Common Shares or Series A Common Shares of the Issuer beneficially owned by the Voting Trust.

Not applicable.

The information contained in Item 4 above is incorporated herein by reference. The Voting Trust holds TDS Series A Common Shares and TDS Common Shares and was created to facilitate long-standing relationships among the trust's certificate holders. Under the terms of the Voting Trust, the trustees hold and vote TDS Series A Common Shares and TDS Common Shares held in the trust. As of August 1, 2025, the Voting Trust holds and the trustees vote 7,210,499 TDS Series A Common Shares and 6,301,814 TDS Common Shares, representing approximately 95.6% of the outstanding TDS Series A Common Shares, and approximately 5.8% of the outstanding TDS Common Shares, and approximately 56.8% of the combined voting power of all outstanding shares of TDS capital stock with respect to matters other than the election of directors (based on 108,232,402 TDS Common Shares and 7,538,781 TDS Series A Common Shares on August 1, 2025). Therefore, the Voting Trust trustees may direct a majority of the combined voting power of TDS which has the voting power to elect all directors of the Issuer and approximately 56.8% of the combined voting power of the Issuer with respect to matters other than the election of directors.

Exhibit 1: Joint Filing Agreement and Signature Appendix A Appendix B Appendix C Appendix D