Exhibit 99.3

From: Erik Prusch

To: Clearwire Employees

Distribution: May 13, 2013 at 6:05am Pacific

Subject: Second Letter to Stockholders

Team –

Today we sent a second letter from Executive Chairman John Stanton to all stockholders reminding them of our board of director’s recommendation to vote for the proposed transaction with Sprint.

The letter states that the board believes that the facts and circumstances surrounding this proposed merger, when fairly assessed, show that the transaction is the best strategic alternative for all stockholders. You can read the entire letter here (press release).

Thank you for continuing to focus on our core objectives. I realize it’s a distracting time, and you will likely continue to see more media and analyst speculation, but let’s stay focused on our daily deliverables as we work to post a strong second quarter.

Erik

Cautionary Statement Regarding Forward-Looking Statements

This Current Report on Form 8-K includes “forward-looking statements” within the meaning of the securities laws. The words “may,” “could,” “should,” “estimate,” “project,” “forecast,” “intend,” “expect,” “anticipate,” “believe,” “target,” “plan,” “providing guidance” and similar expressions are intended to identify information that is not historical in nature.

This Current Report on Form 8-K contains forward-looking statements relating to the proposed merger and related transactions (the “transaction”) between Sprint and Clearwire. All statements, other than historical facts, including statements regarding the expected timing of the closing of the transaction; the ability of the parties to complete the transaction considering the various closing conditions; the expected benefits and efficiencies of the transaction; the competitive ability and position of Sprint and Clearwire; and any assumptions underlying any of the foregoing, are forward- looking statements. Such statements are based upon current plans, estimates and expectations that are subject to risks, uncertainties and assumptions. The inclusion of such statements should not be regarded as a representation that such plans, estimates or expectations will be achieved. You should not place undue reliance on such statements. Important factors that could cause actual results to differ materially from such plans, estimates or expectations include, among others, any conditions imposed in connection with the transaction, approval of the transaction by Clearwire stockholders, the satisfaction of various other conditions to the closing of the transaction contemplated by the merger agreement, and other factors discussed in Clearwire’s and Sprint’s Annual Reports on Form 10- K for their respective fiscal years ended December 31, 2012, their other respective filings with the U.S. Securities and Exchange Commission (the “SEC”) and the proxy statement and other materials that have been or will be filed with the SEC by Clearwire in connection with the transaction. There can be no assurance that the transaction will be completed, or if it is completed, that it will close within the anticipated time period or that the expected benefits of the transaction will be realized.

Clearwire does not undertake any obligation to update any forward-looking statement to reflect events or circumstances after the date on which the statement is made or to reflect the occurrence of unanticipated events. Readers are cautioned not to place undue reliance on any of these forward-looking statements.

Additional Information and Where to Find It

In connection with the transaction, Clearwire has filed a Rule 13e-3 Transaction Statement and a definitive proxy statement with the SEC. The definitive proxy statement has been mailed to the Clearwire’s stockholders. INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THE DEFINITIVE PROXY STATEMENT AND OTHER RELEVANT MATERIALS BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT CLEARWIRE AND THE TRANSACTION. Investors and security holders may obtain free copies of these documents and other documents filed with the SEC at the SEC’s web site at www.sec.gov. In addition, the documents filed by Clearwire with the SEC may be obtained free of charge by contacting Clearwire at Clearwire, Attn: Investor Relations, (425) 505-6494. Clearwire’s filings with the SEC are also available on its website at www.clearwire.com.

Participants in the Solicitation

Clearwire and its officers and directors and Sprint and its officers and directors may be deemed to be participants in the solicitation of proxies from Clearwire stockholders with respect to the transaction. Information about Clearwire officers and directors and their

ownership of Clearwire common shares is set forth in the definitive proxy statement for Clearwire’s Special Meeting of Stockholders, which was filed with the SEC on April 23, 2013. Information about Sprint officers and directors is set forth in Sprint’s Annual Report on Form 10-K for the year ended December 31, 2012, which was filed with the SEC on February 28, 2013. Investors and security holders may obtain more detailed information regarding the direct and indirect interests of the participants in the solicitation of proxies in connection with the transaction by reading the preliminary and definitive proxy statements regarding the transaction, which will be filed by Clearwire with the SEC.