EXHIBIT K Execution Version March 30, 2006 Elk Associates LLC c/o Icahn Associates Corp. 47th Floor 767 Fifth Avenue New York, New York 10153 Re: Termination of Equity Purchase Agreement, dated as of November 4,2005, as amended (the "Equity Purchase...

                                                                EXHIBIT K
                                                              Execution Version



March 30, 2006

Elk Associates LLC
c/o Icahn Associates Corp.
00xx Xxxxx
000 Xxxxx Xxxxxx
Xxx Xxxx, Xxx Xxxx  00000

Re:      Termination of Equity Purchase Agreement, dated as of November 4,2005,
         as amended (the "Equity Purchase Agreement")

Gentlemen:

Pursuant to the  recommendation  of the Special  Committee  of our Board of
Directors,  our Board of Directors has determined that mutual termination of the
Equity  Purchase  Agreement,  without  damages or a break-up  fee, is, under the
circumstances,  in the best  interests of XO Holdings,  Inc. and  therefore,  we
hereby agree to terminate the Equity Purchase Agreement by mutual consent.

Please  confirm your  agreement to likewise  terminate the Equity  Purchase
Agreement by your signature in the space provided below.

Very truly yours,

XO HOLDINGS, INC.



By:  /s/ Xxxx Xxxxxxx
     Name:Xxxx Xxxxxxx
     Title: Chief Executive Officer



Acknowledged and agreed:

ELK ASSOCIATES LLC



By:  Xxxxxx X. Xxxxxxx
     Name:  Xxxxxx X. Xxxxxxx
     Title:  Treasurer