Filed by T-Mobile US, Inc.

pursuant to Rule 425 under the Securities Act of 1933

and deemed filed pursuant to Rule 14a-12

under the Securities Exchange Act of 1934

Subject Company: Sprint Corporation

Commission File No.: 001-04721

The following advertisement was made available in connection with the transaction.

Important Additional Information In connection with the proposed transaction, T-Mobile US, Inc. (“T-Mobile”) has filed a registration statement on Form S-4 (File No. 333-226435), which was declared effective by the U.S. Securities and Exchange Commission (the “SEC”) on October 29, 2018, and which contains a joint consent solicitation statement of T-Mobile and Sprint Corporation (“Sprint”), that also constitutes a prospectus of T-Mobile (the “joint consent solicitation statement/prospectus”), and each party will file other documents regarding the proposed transaction with the SEC. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE JOINT CONSENT SOLICITATION STATEMENT/PROSPECTUS AND OTHER RELEVANT DOCUMENTS FILED WITH THE SEC WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION. The documents filed by T-Mobile may be obtained free of charge at T-Mobile’s website, at www.t-mobile.com, or at the SEC’s website, at www.sec.gov, or from T-Mobile by requesting them by mail at T-Mobile US, Inc., Investor Relations, 1 Park Avenue, 14th Floor, New York, NY 10016, or by telephone at 212-358-3210. The documents filed by Sprint may be obtained free of charge at Sprint’s website, at www.sprint.com, or at the SEC’s website, at www.sec.gov, or from Sprint by requesting them by mail at Sprint Corporation, Shareholder Relations, 6200 Sprint Parkway, Mailstop KSOPHF0302-3B679, Overland Park, Kansas 66251, or by telephone at 913-794-1091. No Offer or Solicitation This communication shall not constitute an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. 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. Cautionary Statement Regarding Forward-Looking Statements This communication contains certain forward-looking statements concerning T-Mobile, Sprint and the proposed transaction between T-Mobile and Sprint. All statements other than statements of fact, including information concerning future results, are forward-looking statements. Such forward-looking statements include, but are not limited to, statements about the benefits of the proposed transaction, including anticipated future financial and operating results, synergies, accretion and growth rates, T-Mobile’s, Sprint’s and the combined company’s plans, objectives, expectations and intentions, and the expected timing of completion of the proposed transaction. There are several factors which could cause actual plans and results to differ materially from those expressed or implied in forward-looking statements, including the risks and uncertainties detailed in the Form S-4, as well as in T-Mobile’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018 and in its subsequent reports on Form 10-Q, including in the sections thereof captioned “Risk Factors” and “Cautionary Statement Regarding Forward-Looking Statements,” as well as in its subsequent reports on Form 8-K, all of which are filed with the SEC and available at www.sec.gov and www.t-mobile.com. Forward-looking statements are based on current expectations and assumptions, which are subject to risks and uncertainties that may cause actual results to differ materially from those expressed in or implied by such forward-looking statements. Given these risks and uncertainties, persons reading this communication are cautioned not to place undue reliance on such forward-looking statements. T-Mobile assumes no obligation to update or revise the information contained in this communication (whether as a result of new information, future events or otherwise), except as required by applicable law. NewTMobile.com #5GFORALL Learn more about how the New T-Mobile will lead the 5G revolution at NewTMobile.com Every now and then, something comes along that changes our lives. Like railroads. And automobiles. These are things that opened up America and let culture, communities and commerce flourish. 5G can do this. But not if it’s just 5G for the few, just incremental improvement or just a marketing label. 5G can be so much more. The New T-Mobile can make it more. With real, nationwide 5G for all. Not the few. Not in a decade, but as soon as possible. Not incremental improvement, but a transformation that will change lives in ways we can’t even imagine yet. With 5G for All, the New T-Mobile can open massive wireless highways and lower the prices to use them. We can ignite innovation and challenge a failed status quo. A status quo that opponents of this merger want to preserve. A status quo that has left too many Americans looking across a digital divide, paying too much for too little, with too few options, tolerating terrible treatment and believing it can’t change. It can change. It should change. The New T-Mobile can and will change it. We can change this failed status quo and lead in the 5G era. We can build the 5G network that America deserves and unleash Americans to do what we do best: create a brighter future for everyone. CREATING A 5G FUTURE FOR ALL