Exhibit 10.15 (j)

AMENDMENT NO. 9 TO GENERAL PURCHASE AGREEMENT

This Amendment No. 9 to General Purchase Agreement (“Amendment No. 9”) is made
and entered into this 27th day of December, 2011 (the “Ninth Amendment Date”),
by and between Alcatel-Lucent USA Inc. (formerly known as Lucent Technologies
Inc.), a Delaware corporation (“Alcatel-Lucent” or “Seller”) having an office at
600 Mountain Avenue, Murray Hill, New Jersey 07974, and MetroPCS Wireless, Inc.,
a Delaware corporation (“Customer”), having an office at 2250 Lakeside
Boulevard, Richardson, Texas 75082.

RECITALS

WHEREAS, Customer and Seller entered into that certain General Purchase
Agreement, effective as of June 6, 2005 (as amended, the “Agreement”);

WHEREAS, Customer and Seller entered into an Amendment No. 1 to the Agreement,
dated September 30, 2005 (“Amendment No. 1”); and

WHEREAS, Customer and Seller entered into an Amendment No. 2 to the Agreement,
dated November 10, 2005 (“Amendment No. 2”);

WHEREAS, Customer and Seller entered into an Amendment No. 3 to the Agreement,
dated December 3, 2007 (“Amendment No. 3”);

WHEREAS, Customer and Seller entered into an Amendment No. 4 to the Agreement,
dated March 23, 2011 (“Amendment No. 4”);

WHEREAS, Customer and Seller entered into an Amendment No. 5 to the Agreement,
dated June 15, 2011 (“Amendment No. 5”);

WHEREAS, Customer and Seller entered into an Amendment No. 6 to the Agreement,
dated September 30, 2011 (“Amendment No. 6”);

WHEREAS, Customer and Seller entered into an Amendment No. 7 to the Agreement,
dated October 28, 2011 (“Amendment No. 7”);

WHEREAS, Customer and Seller entered into an Amendment No. 8 to the Agreement,
dated November 23, 2011 (“Amendment No. 8”) and together with Amendment No. 1,
Amendment No. 2, Amendment No. 3, Amendment No. 4, Amendment No. 5, Amendment
No. 6, Amendment No. 7, Amendment No. 8 and this Amendment No. 9, (the
“Amendments”);

WHEREAS, Customer and Seller wish to amend the Agreement by extending the
Extension Term of the Agreement on the terms and conditions hereinafter set
forth.

NOW, THEREFORE, in consideration of the mutual promises contained herein and
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the undersigned Parties, intending to be legally bound,
hereby agree to the foregoing and as follows:

1.    INCORPORATION OF RECITALS; DEFINED TERMS. The foregoing recitals are
hereby incorporated into this Amendment No. 9 and made a part hereof.
Capitalized terms used herein but not defined herein shall have the meanings
ascribed to them in the Agreement.

2.    AMENDMENTS.

2.1    Section 2.1 of Amendment No. 8, Section 1.2(a) “Initial Term” and Section
1.2(b) “Renewal Terms”. Notwithstanding anything to the contrary under Amendment
No. 8 and Section 1.2(a), Initial Term and Section 1.2(b) Renewal Terms of the
Agreement, the Parties hereby extend the Extension Term of the Agreement until
such time as the Parties execute a new agreement replacing in its entirety the
Agreement.

Alcatel-Lucent/ MetroPCS Proprietary Information
Page 1 of 2

--------------------------------------------------------------------------------

3.    MISCELLANEOUS. Except for those provisions of the Agreement which are
expressly modified herein, all of the other terms and conditions of the
Agreement, including all Attachments thereto, shall remain unmodified. In case
of any conflict between the provisions of this Amendment No. 9 and those of the
Agreement, the provisions of this Amendment No. 9 will take precedence. This
Amendment No. 9 and the non-conflicting terms of the Agreement constitute the
entire agreement between the Parties with respect to the subject matter hereof
and supersede all prior and contemporaneous understandings (both written and
oral) between Seller and Customer with respect to such subject matter.

IN WITNESS WHEREOF, the Parties have caused this Amendment No. 9 to be executed
by their duly authorized representatives as of the Ninth Amendment Date.

METROPCS WIRELESS, INC.
 
ALCATEL-LUCENT USA INC. (formerly known as Lucent Technologies Inc.)
By: /s/ J. Braxton Carter
 
By: /s/ Matthew Keil
Name: J. Braxton Carter
 
Name: Matthew Keil
Title: Vice Chairman & CFO
 
Title: National Sales Director
Date: 12/27/11
 
Date: 12/27/11

Alcatel-Lucent/ MetroPCS Proprietary Information
Page 2 of 2