SUPPLEMENTAL INDENTURE

Exhibit 10.17

EXECUTION COPY

SUPPLEMENTAL INDENTURE

Supplemental Indenture (this “ Supplemental Indenture ”), dated as of July 30, 2008, among Clear Channel Capital I, LLC, a Delaware limited liability company (“ Holdings ”), the direct parent of Clear Channel Communications, Inc., a Texas corporation (the “ Issuer ”), each of the Issuer’s Restricted Subsidiaries party hereto (collectively, the “ Restricted Guarantors ,” and together with Holdings, the “ Guarantors ”) and Law Debenture Trust Company of New York, as trustee (the “ Trustee ”).

WITNESSETH

WHEREAS, Clear Channel Communications, Inc. has heretofore executed and delivered to the Trustee an indenture (the “ Indenture ”), dated as of July 30, 2008, providing for the issuance of an unlimited aggregate principal amount of 10.75% Senior Cash Pay Notes due 2016 (the “ Senior Cash Pay Notes ”) and 11.00% / 11.75% Senior Toggle Notes due 2016 (the “ Senior Toggle Notes ” and together with the Senior Cash Pay Notes, the “ Notes ”);

WHEREAS, the Indenture provides that under certain circumstances the Guarantors shall execute and deliver to the Trustee a supplemental indenture pursuant to which the Guarantors shall unconditionally guarantee all of the Issuer’s Obligations under the Notes and the Indenture on the terms and conditions set forth herein and in the Indenture (the “ Guarantee ”); and

WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee is authorized to execute and deliver this Supplemental Indenture.

NOW THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged, the parties mutually covenant and agree for the equal and ratable benefit of the Holders of the Notes as follows:

(1) Capitalized Terms . Capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture.

(2) Agreement to Guarantee . Each of the Guarantors hereby agrees to provide an unconditional Guarantee on the terms and subject to the conditions set forth in the Indenture including but not limited to Articles 10 and 11 thereof.

(3) No Recourse Against Others . No past, present or future director, officer, employee, incorporator, member, partner or stockholder of any Guarantor or any of its direct or indirect parent companies shall have any liability for any obligations of the Issuer or the Guarantors (including the Guarantors party hereto) under the Notes, any Guarantees, the Indenture or this Supplemental Indenture or for any claim based on, in respect of, or by reason of, such obligations or their creation. Each Holder by accepting Notes waives and releases all such liability. The waiver and release are part of the consideration for issuance of the Notes and the Guarantee provided herein.

(4) Governing Law . THIS SUPPLEMENTAL INDENTURE WILL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

(5) Counterparts . The parties may sign any number of copies of this Supplemental Indenture. Each signed copy shall be an original, but all of them together represent the same agreement.

(6) Effect of Headings . The Section headings herein are for convenience only and shall not affect the construction hereof.

(7) The Trustee . The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or for or in respect of the recitals contained herein, all of which recitals are made solely by the Guarantors.

(8) Subrogation . Each Guarantor shall be subrogated to all rights of Holders of Notes against the Issuer in respect of any amounts paid by the Guarantors pursuant to the provisions of Section 2 hereof and Section 10.01 of the Indenture; provided that, if an Event of Default has occurred and is continuing, the Guarantors shall not be entitled to enforce or receive any payment