W I T N E S S E T H:

TWELFTH SUPPLEMENTAL INDENTURE (this “Twelfth Supplemental Indenture”), dated as of December 8, 2014, among WesTower Communications Inc., a Delaware corporation (the “New Guarantor”), MASTEC, INC., a Florida corporation (the “Company”), and U.S. BANK NATIONAL ASSOCIATION, as trustee under the Indenture referred to below (the “Trustee”).

WHEREAS the Company has heretofore executed and delivered to the Trustee an indenture (as amended, supplemented or otherwise modified, the “Indenture”) dated as of June 5, 2009, providing for (i) the issuance by the Company from time to time of its senior debt securities evidencing its unsecured and unsubordinated indebtedness, in an unlimited aggregate principal amount, in one or more series and (ii) the guaranty of such securities by the guarantors party thereto;

WHEREAS the Company has heretofore supplemented the Indenture by, among other things, executing and delivering to the Trustee (i) the Second Supplemental Indenture, dated as of November 10, 2009 (the “Second Supplemental Indenture”), by and among the Company, the guarantors party thereto and the Trustee, relating to the Company’s original 4.25% Convertible Senior Notes due 2014 (the “Original 4.25% Senior Convertible Notes”), (ii) the Fourth Supplemental Indenture, dated as of January 11, 2011 (the “Fourth Supplemental Indenture”), by and among the Company, the guarantors party thereto and the Trustee, relating to the Company’s new 4.25% Senior Convertible Notes due 2014 (the “New 4.25% Senior Convertible Notes” and, together with the Original 4.25% Senior Convertible Notes, the “4.25% Senior Convertible Notes”), (iii) the Fifth Supplemental Indenture, dated as of March 18, 2013 (the “Fifth Supplemental Indenture”), by and among the Company, the guarantors party thereto and the Trustee, relating to the Company’s 4.875% Senior Notes due 2023 (the “Senior Notes” and, together with the 4.25% Senior Convertible Notes, the “Notes”), (iv) the Sixth Supplemental Indenture, dated as of September 30, 2013, by and among the Company, the guarantors party thereto and the Trustee, relating to the joinder of certain subsidiaries of the Company as subsidiary guarantors, (v) the Seventh Supplemental Indenture, dated as of November 11, 2013, by and among the Company, the guarantors party thereto and the Trustee, relating to the joinder of certain subsidiaries of the Company as subsidiary guarantors, (vi) the Eighth Supplemental Indenture, dated as of March 12, 2014, by and among the Company, the guarantors party thereto and the Trustee, relating to the joinder of certain subsidiaries of the Company as guarantors of the Original 4.25% Senior Convertible Notes, (vii) the Ninth Supplemental Indenture, dated as of April 30, 2014, by and among the Company, the guarantors party thereto and the Trustee, relating to the joinder of certain subsidiaries of the Company as guarantors of the 4.25% Senior Convertible Notes, (viii) the Tenth Supplemental Indenture, dated as of July 10, 2014, by and among the Company, the guarantors party thereto and the Trustee, relating to the joinder of certain subsidiaries of the Company as subsidiary guarantors, and (ix) the Eleventh Supplemental Indenture, dated as of August 8, 2014, by and among the Company, the guarantors party thereto and the Trustee, relating to the joinder of certain subsidiaries of the Company as guarantors of the Senior Notes;

WHEREAS Section 4.04 of the Second Supplemental Indenture, Section 4.04 of the Fourth Supplemental Indenture and Section 4.15 of the Fifth Supplemental Indenture each provide that

under certain circumstances, the Company is required to cause the New Guarantor to execute and deliver to the Trustee a supplemental indenture pursuant to which the New Guarantor shall unconditionally guarantee all the Company’s obligations under the Notes and the Indenture on the terms and conditions set forth herein (the “Guarantee”); and

WHEREAS pursuant to Section 901 of the Indenture, Section 6.01 of the Second Supplemental Indenture, Section 6.01 of the Fourth Supplemental Indenture and Section 9.01 of the Fifth Supplemental Indenture, the Trustee, the Company and the New Guarantor are each 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 New Guarantor, the Company and the Trustee mutually covenant and agree for the equal and ratable benefit of the holders of the Notes as follows: