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Exhibit 31.1

CERTIFICATIONS

I, Carl J. Grivner, certify that:

1.     I have reviewed this quarterly report on Form 10-Q of XO Communications,
Inc.;

2.     Based on my knowledge, this quarterly report does not contain any untrue
statement of a material fact or omit to state a material fact necessary to make
statements made, in light of the circumstances under which such statements were
made, not misleading with respect to the period covered by this report;

3.     Based on my knowledge, the financial statements, and other financial
information included in this quarterly report, fairly present in all material
respects the financial condition, results of operations and cash flows of the
registrant as of, and for, the periods presented in this quarterly report;

4.     The registrants other certifying officer and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant and have:



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| | a) designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our supervision, to
ensure that material information relating to the registrant, including its
consolidated subsidiaries, is made known to us by others within those
entities, particularly during the period in which this quarterly report is
being prepared;
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| | b) evaluated the effectiveness of the registrants disclosure controls and
procedures and presented in this quarterly report our conclusions about the
effectiveness of the disclosure controls and procedures, as of the end of
the period covered by this report based on such evaluation; and                                                                                           
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| | c) disclosed in this report any change in the registrants internal control
over financial reporting that occurred during the registrants most recent
fiscal quarter that has materially affected, or is reasonably likely to
materially affect, the registrants internal control over financial
reporting; and                                                                          

5.     The registrants other certifying officer and I have disclosed, based on our
most recent evaluation of internal control over financial reporting, to the
registrants auditors and the audit committee of registrants board of
directors (or persons performing the equivalent function):



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| | a) all significant deficiencies and material weaknesses in the design or
operation of internal controls over financial reporting which are reasonably
likely to adversely affect the registrants ability to record, process,
summarize and report financial information; and
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| | b) any fraud, whether or not material, that involves management or other
employees who have a significant role in the registrants internal control
over financial reporting.                                                                                                

Date: November 10, 2003

/s/ Carl J. GrivnerCarl J. GrivnerChief Executive Officer(Principal Executive Officer)


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