This Equity Acceleration Agreement (“Agreement”) is entered into as of July 24, 2025 (“Effective Date”) by and between Doug Chambers (“Associate”) and United States Cellular Corporation (the “Company”) (together, the “Parties”).

WHEREAS, the Company has adopted and maintains the United States Cellular Corporation Long-Term Incentive Plan (the “Plan”), under which the Company has granted to Associate the award(s) set forth on Exhibit A to this Agreement (the “Awards”).

WHEREAS, the Company has entered into a Securities Purchase Agreement, dated as of May 24, 2024, by and among the Company, Telephone and Data Systems, Inc. (“TDS”), USCC Wireless Holdings, LLC (“USCC Wireless”), and T-Mobile US, Inc. (“Buyer”), pursuant to which the Company intends to sell to Buyer its wireless operations and select spectrum assets (the date on which such sale closes, the “Closing Date,” and the closing of such acquisition, the “Change in Control”);

WHEREAS, the Company recognizes the work Associate performs, and in anticipation of this continuing need after the Closing Date, wishes to reward Associate with accelerated vesting of the Awards effective as of the Closing Date, but subject to repayment if Associate voluntarily leaves employment with the Company or one of its affiliates (collectively, the “Company Group”) prior to January 1, 2026 (or such earlier date specified by the Company as the date of Associate’s employment termination) (“Retention Period”) for a reason other than “Good Reason” (as defined in the Plan), or if Associate fails to satisfactorily meet performance expectations through the end of the Retention Period, such continued employment and satisfactory performance both of which are required in order to retain the benefits of the Acceleration (as defined below) (the requirements set forth in this paragraph, the “Retention Conditions”); and

WHEREAS, the Parties acknowledge and agree that this Agreement does not constitute a contract of employment or a guarantee of employment or any term or condition of employment, including compensation, and Associate continues to be employed on an at-will basis. As such, Associate’s employment with the Company Group may be terminated by Associate or any member of the Company Group that employs Associate at any time for any reason, without prior notice or warning.

NOW, THEREFORE, in consideration of the mutual covenants and agreements set forth in this Agreement, the Parties acknowledge and agree as follows:

1.Recitals. The Parties acknowledge and agree that the foregoing recitals are an integral part of this Agreement and incorporated herein by reference.

2.Equity Award Acceleration. Provided Associate signs, dates and returns this Agreement to the Company, and subject to the approval of the Company’s Board of Directors or its Long-Term Incentive Compensation Committee and the continued employment of Associate through the Closing Date, effective immediately following the later of the Change in Control and the Effective Date (such later date, the “Acceleration Date” and the treatment described in this Section 2, the “Acceleration”), all Awards shall fully vest, and shall be settled within 60 days following such Acceleration Date (in the case of outstanding Performance Awards granted in 2025, if any, based on deemed 100% achievement of target performance).

3.Repayment. Associate acknowledges and agrees that the Acceleration is an advance of unearned compensation that will not be earned by Associate unless Associate satisfies all of the Retention Conditions. Therefore, Associate agrees that if Associate fails to satisfy all of the Retention Conditions through the conclusion of the Retention Period, Associate shall pay the Company, within five business days of receipt by Associate of a written demand therefor, an amount in cash equal to (x) the number of shares of Common Stock (as defined in the Plan) subject to the portions of the Awards that vested on account of the Acceleration, multiplied by (y) the Fair Market Value (as defined in the Plan) of a share of Common Stock on the Acceleration Date (the “Repayment Amount”).

Associate acknowledges and agrees that the Awards, by encouraging stock ownership and thereby increasing an employee’s proprietary interest in the Company Group’s success, are intended as incentives to participating employees to remain in the employ of the Company Group. Associate acknowledges and agrees that this Section 3 is therefore fair and reasonable, and not a penalty. To satisfy Associate’s repayment obligation, Associate authorizes any applicable member of the Company Group to deduct from Associate’s last paycheck (or any other compensation payable to Associate) up to and including the entire Repayment Amount, unless otherwise prohibited by state law. Associate agrees to execute any documents at the time of setoff required by any member of the Company Group in order to effectuate such setoff. This right of setoff shall not be an exclusive remedy (i.e., the Company shall be entitled to any other remedy permitted under applicable law) and the Company Group’s election not to exercise this right of setoff with respect to any amount payable to Associate shall not constitute a waiver of this right of setoff with respect to any other amount payable to Associate or any other remedy. Associate further acknowledges and agrees that it will be his/her/their responsibility to address payment of any remaining indebtedness for the Repayment Amount with Human Resources. Should Associate fail to repay the entire gross Repayment Amount, the Company Group will seek any and all remedies available by law and Associate agrees that the Company Group will be entitled to reimbursement from Associate of all expenses, including attorneys’ fees, incurred by the Company Group as a result of any collection efforts.

4.Choice of Law and Severance of Agreement Provisions. This Agreement shall be governed by and construed in accordance with the laws of the State of Delaware, without reference to principles of conflicts of laws. Associate agrees that any action or proceeding in connection with any claim arising out of or related to this Agreement, whether in tort or contract or at law or in equity, shall be brought exclusively in the United States District Court for the Northern District of Illinois or the courts of the State of Illinois (the “Chosen Courts”) and (i) irrevocably submits to the exclusive jurisdiction of the Chosen Courts, (ii) waives any objection to laying venue in any such action or proceeding in the Chosen Courts for purposes of any such action or proceeding, (iii) waives any objection that the Chosen Courts are an inconvenient forum or do not have jurisdiction over any party and (iv) consents to the service of process in any such action or proceeding by certified or registered mailing of the summons and complaint therein directed to Associate at Associate’s last known address on file with the Company. Associate hereby irrevocably waives any right to trial by jury in any legal proceeding arising out of or related to this Agreement. The Parties agree that in the event that any part of the Agreement shall be declared invalid, it shall not affect the validity of any of the remaining terms or provisions of the Agreement. Moreover, if any one or more of the provisions contained in this Agreement are held to be excessively broad as to duration, scope, activity or subject, such provisions will be construed by limiting and reducing them so as to be enforceable to the maximum extent compatible with applicable law.

5.Assignment of this Agreement. This Agreement may not be assigned, or any rights or obligations hereunder delegated, in whole or in part, by Associate without the prior written consent of the Company. The Company may assign this Agreement to another employing entity within the TDS family of companies, which entity will then be considered the Company for purposes of this Agreement, upon written notice to Associate.

6.Counterparts. This Agreement may be executed in counterparts, and each counterpart, when executed, shall have the efficacy of a signed original. Photographic and electronic copies of such signed counterparts may be used in lieu of the originals for any purpose.

WHEREFORE, Associate hereby affirms and acknowledges that Associate has read the foregoing and is aware of Associate’s right to consult an attorney before signing the Agreement and has either consulted an attorney or elected not to exercise such right. Associate further affirms that Associate understands the meaning of the terms of this Agreement and their effect, and that Associate agrees that the provisions set forth in the Agreement are written in language that Associate understands. Associate represents that Associate has not relied on any representations or commitments other than as expressly set forth herein and enters into this Agreement freely and voluntarily with full knowledge of its implications.

July 24, 2025

Douglas W. Chambers

Subject:        Appointment as President and Chief Executive Officer of Array Digital Infrastructure, Inc.

Dear Doug,

On behalf of the organization, I am pleased to present our offer for your transition to President and Chief Executive Officer of Array Digital Infrastructure, Inc. (as UScellular will be renamed). This offer is subject to approval by the Board of Directors of UScellular (the “Board”) and will be effective upon the closing of the Company’s sale of its wireless operations and select spectrum assets to T-Mobile (the “T-Mobile Closing”). Your service as President and Chief Executive Officer of Array Digital Infrastructure will be on an interim basis.

The following summarizes pertinent compensation and benefits information, effective as of the date of your appointment:

Base Salary: You will continue to receive an annual base salary of $620,500 (subject to applicable withholdings). Merit increases for executives are determined in the beginning of February each calendar year, with an effective date that is applied retroactively to January 1st of that year.

Annual Target Bonus: Your annualized target bonus opportunity for 2025 will remain 55% of your base earnings. Your 2025 annual bonus will be paid in two installments. The first installment will be paid for the period prior to the T-Mobile Closing and will be paid at the time of the T-Mobile Closing. The second installment will be paid for the period following the T-Mobile Closing and will be paid following year-end. However, if you separate from the Company prior to the end of 2025, the second installment will be paid at the time of your separation and will be pro-rated based on the portion of the period following the T-Mobile Closing that you worked.

Long-Term Incentive Program (LTIP): If your employment continues in 2026, you will be eligible to participate in the Company’s Long-Term Incentive Plan (LTIP). Assuming the LTIP continues in its current form, your anticipated Long-Term Incentive (LTI) target grant date value for 2026 will be 160% of your annual base salary on the date of the grant. The Long-Term Incentive grants are subject to the approval of the Board and are not guaranteed in any year.

Benefits: You will continue to be provided with the same medical, life insurance, and 401(k) benefits as the organization extends to its similarly situated executives.

Severance: Upon your separation from the Company, you will be eligible for severance in an amount that is no less than the amount that you would have been eligible for under the Company’s Compensation Due at Time of Separation for Executive Officers Policy had you separated, under the same circumstances, on the date of the T-Mobile Closing. For the avoidance of doubt, this severance will be conditioned upon you executing (and not revoking) a release of all claims against the Company and its affiliates in the form provided by the Company.

Your employment remains at−will, meaning either you or the Company can end your employment at any time, with or without notice or cause. Neither this letter nor any other oral or written statements or representations regarding your employment may alter your at-will status or may be considered an employment contract. The Company reserves the right to change or terminate the compensation and benefits arrangements described herein, and any other compensation and benefits arrangements, at any time for any reason.

Doug, as you have experienced, our dynamic organization is an exciting and fulfilling place to work. We take pride in providing a rewarding career for our associates. We are very excited about you moving into your interim position and anticipate a mutually rewarding working relationship.

Thank you for taking on this critical position.

Sincerely,

/s/ LeRoy T. Carlson, Jr.

LeRoy T. Carlson, Jr.

Chairman of the Board

By my signature below, I acknowledge and certify that I have read, fully understand and accept all terms of the foregoing offer to serve as interim President and Chief Executive Officer of Array Digital Infrastructure, Inc.

Agreed and accepted:

CHICAGO (July 24, 2025) — United States Cellular Corporation (NYSE:USM) (the “Company”) today announced that it expects its Board of Directors to approve a special cash dividend in the aggregate range amount of $1.950 billion - $2.075 billion following the closing of the sale of the Company’s wireless operations and select spectrum assets to T-Mobile US, Inc. The expected dividend is in the range of $22.50 - $23.75 per Common Share and Series A Common Share. The board is expected to set a record and payment date at the time of declaration.

"We are pleased to provide additional clarity on the expected special dividend to UScellular shareholders, subject to the approval of the Board of Directors and contingent on the closing of the T-Mobile transaction. We expect this to be the first of potentially several special dividends issued to shareholders as a result of our announced transactions,” said Laurent Therivel, UScellular President and CEO. “We believe that payment of a dividend in this approximate amount will leave the post-closing business with ample liquidity and financial flexibility to meet capital requirements and general business needs for the foreseeable future.”

The following table provides a reconciliation between the gross purchase price and the expected net cash available for distribution following the expected close of the T-Mobile transaction. Certain amounts in this table are estimates:

(1)    Expected proceeds at closing include $400 million of funds from the sale of spectrum licenses related to designated entities. Final UScellular buyout of the equity interest in the designated entities has been completed. As such, those licenses are expected to be conveyed to T-Mobile upon the initial closing.

(2)    Excess cash - Represents a substantial majority of cash on hand at the beginning of 2025 and cash generated by UScellular’s business in 2025. UScellular’s remaining business, after sale of its wireless operations, will have a significantly different financial and operational profile, and is also significantly smaller in size. Accordingly, the cash balance required to operate and meet the working capital and investment needs of the remaining business is expected to be substantially less than the corresponding cash balance required to operate UScellular’s legacy business that includes its wireless operations. Such excess cash is included in the amount available for payment of the expected special dividend.

Telephone and Data Systems, Inc. (NYSE:TDS), which is expected to own approximately 81% of the equity of UScellular as of the closing of the T-Mobile transaction, will receive its pro-rata share of the special dividend.

Additional Developments - In a separate press release issued today, UScellular announced two additional developments that are also subject to the closing of the sale of the wireless operations. First, upon closing, the Company intends to change its name to Array Digital Infrastructure, Inc. Second, Doug Chambers will serve as interim CEO of the post-closing Array business. For more information, please refer to the press release which can be accessed on the Company’s website.

United States Cellular Corporation provides a comprehensive range of wireless products and services, excellent customer support, and a high-quality network to customers with 4.4 million retail connections in 21 states. The Chicago-based company had 4,100 full- and part-time associates as of March 31, 2025. For more information about UScellular, visit uscellular.com.

Safe Harbor Statement Under the Private Securities Litigation Reform Act of 1995:  All information set forth in this news release, except historical and factual information, represents forward-looking statements. This includes statements regarding the amount of the expected dividend to be paid following the expected closing of the T-Mobile transaction and statements regarding the various items shown above that impact the calculation of that expected dividend. These statements are based on current estimates, projections, and assumptions, which involve certain risks and uncertainties that could cause actual results to differ materially from those in the forward-looking statements. Important factors that may affect these forward-looking statements include but are not limited to: whether the announced transactions whereby UScellular has agreed to sell its wireless operations and selected spectrum assets will be successfully completed, whether the USCC Board will elect to declare the dividend and whether an unexpected development will arise that impacts the cash currently expected to be available following the closing. Investors are encouraged to consider these and other risks and uncertainties that are more fully described under “Risk Factors” in the most recent filing of UScellular's Form 10-K, as updated by any UScellular Form 10-Q filed subsequent to such Form 10-K.

Colleen Thompson, Vice President-Corporate Relations

colleen.thompson@tdsinc.com

Julie Mathews, IRC, Director – Investor Relations

julie.mathews@tdsinc.com

    

Appoints Doug Chambers as interim President and CEO of ArraySM

CHICAGO (July 24, 2025) — United States Cellular Corporation (NYSE:USM) announced two developments today, each of which is subject to and will become effective upon the closing of the previously announced sale (the “T-Mobile Transaction”) of its wireless operations to T-Mobile US, Inc. The T-Mobile Transaction is expected to close on August 1, 2025, subject to satisfaction of closing conditions. Upon closing:

•Douglas W. Chambers will serve as interim President and Chief Executive Officer (CEO) of the post-closing business

•The post-closing business will change its name to Array Digital Infrastructure, Inc.SM

Chambers currently serves as Executive Vice President, Chief Financial Officer and Treasurer of UScellular. As interim CEO of Array, he will be responsible for overseeing operations and strategic initiatives related to the portfolio of 4,400 owned towers, noncontrolling investment interests and retained wireless spectrum.

“As we progress through the divestiture of the wireless operations, we are pleased to take these next steps in announcing leadership as well as the new legal name, Array Digital Infrastructure, Inc., of the post-closing company. Doug brings decades of industry experience and a robust understanding of the company’s strategy and overall operations, making him well suited to serve as interim President and CEO,” said LeRoy T. Carlson, Jr., UScellular Board Chair. “The Board is confident that Doug is the right leader to oversee the successful transition to Array while we consider potential choices for a permanent CEO.”

“I am honored to assume the role of interim CEO of Array at this pivotal time for the company,” said Chambers. “We have a great opportunity ahead of us and I look forward to working with the Board and our management team to continue to strengthen our tower business, seek opportunities to monetize our retained spectrum, and work towards closing the announced spectrum transactions.”

Mr. Chambers joined the TDS family of companies in 2007 and has served as Executive Vice President, CFO and Treasurer of UScellular for the past six years. He also currently serves on the board of UScellular.

In connection with the name change, the Company intends to change its ticker symbol on the NYSE to “AD” for its Common Stock. The new ticker symbol will replace the Company’s current ticker symbol “USM” which has been used since its initial public offering in 1988.

As part of the corporate name change, the Company will launch a new website and a new company logo. Array Digital Infrastructure, Inc. expects to remain headquartered in Chicago, IL.

Additional Developments - In a separate press release issued today, UScellular also announced that it expects its board of directors to approve a special cash dividend in the range of $22.50 - $23.75 per Common Share and Series A Common Share following the closing of the sale of the wireless operations. For further information, please refer to the press release which can be accessed on the Company’s website.

United States Cellular Corporation provides a comprehensive range of wireless products and services, excellent customer support, and a high-quality network to customers with 4.4 million retail connections in 21 states. The Chicago-based company had 4,100 full- and part-time associates as of March 31, 2025. At the end of the first quarter of 2025, Telephone and Data Systems, Inc. (NYSE: TDS) owned approximately 83 percent of UScellular. For more information about UScellular, visit uscellular.com.

Safe Harbor Statement Under the Private Securities Litigation Reform Act of 1995: All information set forth in this news release, except historical and factual information, represents forward-looking statements. This includes all statements about the company’s plans, beliefs, estimates, and expectations, including with respect to the expected closing date of the transaction with T-Mobile. These statements are based on current estimates, projections, and assumptions, which involve certain risks and uncertainties that could cause actual results to differ materially from those in the forward-looking statements. Important factors that may affect these forward-looking statements include but are not limited to: whether the announced transactions whereby UScellular has agreed to sell its wireless operations and selected spectrum assets will be successfully completed. Investors are encouraged to consider these and other risks and uncertainties that are more fully described under “Risk Factors” in the most recent filing of UScellular's Form 10-K, as updated by any UScellular Form 10-Q filed subsequent to such Form 10-K.

Colleen Thompson, Vice President - Corporate Relations of TDS

colleen.thompson@tdsinc.com

Julie Mathews, IRC, Director - Investor Relations of TDS

julie.mathews@tdsinc.com