Exhibit 10.1

SECOND AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT

Dated as of June 5, 2001

between

XO Communications, Inc.

and

The Purchasers Listed on the Signature Pages Hereto





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SECOND AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT, dated as of
June 5, 2001 between XO Communications, Inc., a Delaware corporation (the
Company), and the entities listed on the signature pages hereto under the
caption Purchasers (each a Purchaser and, collectively, the Purchasers).

Pursuant to the Stock Purchase Agreement, dated December 7, 1999 (the
1999 Stock Purchase Agreement), by and between the Company and certain of the
Purchasers, on January 20, 2000, the Purchasers acquired (i) an aggregate of
584,375 shares of the Companys Series C Preferred Stock, par value $0.01 per
share (the Series C Preferred Stock), and (ii) an aggregate of 265,625 shares
of the Companys Series D Preferred Stock, par value $0.01 per share (the
Series D Preferred Stock).

Pursuant to the Stock Purchase Agreement, dated as of June 14, 2000 (the
2000 Stock Purchase Agreement), by and between the Company and the
Purchasers, the Purchasers acquired (i) an aggregate of 268,750 shares of the
Companys Series G Preferred Stock, par value $0.01 per share (the Series G
Preferred Stock), and (ii) an aggregate of 131,250 shares of the Companys
Series H Preferred Stock, par value $0.01 per share (the Series H Preferred
Stock and, collectively with the Series C Preferred Stock, Series D Preferred
Stock and the Series G Preferred Stock, the Preferred Shares).

In connection with the consummation of the transactions contemplated by
the 2000 Stock Purchase Agreement, the Company and the Purchasers entered into
an Amended and Restated Registration Rights Agreement, dated as of July 6, 2000
(the Existing Registration Rights Agreement), pursuant to which the Company
granted the Purchasers certain rights with respect to the registration of the
shares of Common Stock (as hereinafter defined) issuable upon conversion of the
Preferred Shares.

Pursuant to the Amendment and Stock Purchase Agreement, dated as of April
25, 2001 (the Amendment and Stock Purchase Agreement), by and between the
Company and the Purchasers (i) the Company is amending (the Amendments) the
Certificates of Designation (as defined in the Amendment and Stock Purchase
Agreement) with respect to the Preferred Shares and (ii) the Purchasers are
purchasing an aggregate of 50 million shares of the Companys Class A Common
Stock, par value $.02 per share (the Class A Common Stock).

The Company and the Purchasers desire to further amend and restate the
Existing Registration Rights Agreement in its entirety to provide for the
rights of the Purchasers with respect to the registration of the shares of
Common Stock held by the Purchasers and the shares of Common Stock issuable
upon conversion of the Preferred Shares.





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Accordingly, as part of, and as consideration for, the acquisition of the
Preferred Shares by the Purchasers from the Company pursuant to the 1999 Stock
Purchase Agreement and the 2000 Stock Purchase Agreement and the purchase of
the Class A Common Stock and the Amendments pursuant to the Amendment and Stock
Purchase Agreement, the Company hereby grants to the Purchasers certain
registration and other rights with respect to its shares of Class A Common
Stock as more fully set forth herein.

Accordingly, the parties hereto agree to amend and restate the Existing
Registration Rights Agreement in its entirety as follows:

1.      Definitions. As used herein, unless the context otherwise requires,
the following terms have the following respective meanings:

Certificate of Incorporation means the Certificate of Incorporation of
the Company, as it may be amended or restated hereafter from time to time.

Commission means the Securities and Exchange Commission or any other
Federal agency at the time administering the Securities Act.

Common Stock means any shares of Class A Common Stock of the Company,
now or hereafter authorized to be issued, and any and all securities of any
kind whatsoever of the Company which may be exchanged for or converted into
Common Stock, any and all securities of any kind whatsoever of the Company
which may be issued on or after the date hereof in respect of, in exchange for,
or upon conversion of shares of Common Stock pursuant to a merger,
consolidation, stock split, stock dividend, recapitalization of the Company or
otherwise.

Exchange Act means the Securities Exchange Act of 1934, as amended, or
any similar Federal statute, and the rules and regulations of the Commission
thereunder, all as the same shall be in effect at the time. Reference to a
particular section of the Exchange Act shall include a reference to the
comparable section, if any, of any such similar Federal statute.

Person means a corporation, an association, a partnership, an
organization, a business, a trust, an individual, or any other entity or
organization, including a government or political subdivision or an
instrumentality or agency thereof.

Registrable Securities means (i) any shares of Common Stock issued
or issuable upon the conversion of any Preferred Shares held by the Purchasers,
(ii) any shares of Common Stock issued to any of the Purchasers pursuant to the
Amendment and Stock Purchase Agreement and (iii) any shares of Common Stock
issued with respect to the Preferred Shares or the Common Stock referred to in
clauses (i) and (ii) by way of a stock dividend, stock split or reverse
stock split or in connection with a combination of

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shares, recapitalization, merger, consolidation or otherwise. As to any
particular Registrable Securities, such securities shall cease to be
Registrable Securities (a) when a registration statement with respect to
the sale of such securities shall have become effective under the Securities
Act and such securities shall have been disposed of in accordance with such
registration statement, (b) when such securities shall have been otherwise
transferred, new certificates for them not bearing a legend restricting further
transfer shall have been delivered by the Company and subsequent public
distribution of them shall not require registration of them under the
Securities Act, (c) when such securities are eligible for sale under Rule
144(k) or any successor provision, or (d) when such securities shall have
been sold as permitted by, and in compliance with, the Securities Act.

Registration Expenses means all expenses incident to the registration
and disposition of the Registrable Securities pursuant to Section 2 hereof,
including, without limitation, all registration, filing and applicable national
securities exchange fees, all fees and expenses of complying with state
securities or blue sky laws (including fees and disbursements of counsel to the
underwriters or the Purchasers in connection with blue sky qualification of
the Registrable Securities and determination of their eligibility for
investment under the laws of the various jurisdictions), all word processing,
duplicating and printing expenses, all messenger and delivery expenses, the
fees and disbursements of counsel for the Company and of its independent public
accountants, including the expenses of cold comfort letters or any special
audits required by, or incident to, such registration, all fees and
disbursements of underwriters (other than underwriting discounts and
commissions), all transfer taxes, and all fees and expenses of counsel to the
Purchasers; provided, however, that Registration Expenses shall exclude, and
the Purchasers shall pay, underwriting discounts and commissions in respect of
the Registrable Securities being registered.

Securities Act means the Securities Act of 1933, as amended, or any
similar Federal statute, and the rules and regulations of the Commission
thereunder, all as the same shall be in effect at the time. References to a
particular section of the Securities Act shall include a reference to the
comparable section, if any, of any such similar Federal statute.



| | 2. |  | Registration Under Securities Act, etc.
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| |    |  | 2.1      Registration on Request.      

(a)      Request. The Purchasers shall have the right to require the Company
to effect the registration under the Securities Act of all or part of the
Registrable Securities, by delivering a written request therefor to the Company
specifying the number of shares of Registrable Securities and the intended
method of distribution. The Company shall (i) use its reasonable best
efforts to effect the registration under the Securities Act (including by means
of a shelf registration pursuant to Rule 415 under the

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Securities Act if so requested in such request and if the Company is then
eligible to use such a registration) of the Registrable Securities which the
Company has been so requested to register by the Purchasers, for distribution
in accordance with the intended method of distribution set forth in the written
request delivered by the Purchasers, such registration to be effected as
expeditiously as possible (but in any event within 90 days of receipt of a
written request), and (ii) if requested by the Purchasers, use its
reasonable best efforts to obtain acceleration of the effective date of the
registration statement relating to such registration.

(b)      Registration of Other Securities. Whenever the Company
shall effect a registration pursuant to this Section 2.1 in connection with an
underwritten offering by the Purchasers of Registrable Securities, no
securities other than Registrable Securities shall be included among the
securities covered by such registration if inclusion of such other securities
would result in a request by the managing underwriters for a reduction in the
number of Registrable Securities requested to be so registered, except as
required by the terms of (i) registration rights agreements in effect on
January 20, 2000, (ii) the registration rights agreement, dated as of June 16,
2000, between NM Acquisition Corp. and Craig O. McCaw, (iii) the Warrant
Registration Rights Agreement, dated as of December 18, 1997, by and among the
Company (as successor to Concentric Network Corporation) and certain other
parties thereto, (iv) the Registration Rights Agreement, dated as of April 11,
2000, among the Company, Stanley Marsh 3 and the other persons party thereto
and (v) the registration rights agreement, dated as of January 12, 2001, by and
among the Company, Salomon Smith Barney Inc. and Goldman, Sachs & Co. (all such
registration rights agreements, collectively, the Existing Registration Rights
Agreements). If such Registrable Securities requested to be included in a
registration pursuant to this Section 2.1, together with other securities
requested to be included in such registration, would result in a request by the
managing underwriters for a reduction in the number of such Registrable
Securities and other securities requested to be so registered, then the Company
will be required to include in such registration only the amount of Registrable
Securities and other securities which it is so advised can be included in such
registration. In such event, securities shall be registered, subject to the
terms of the Existing Registration Rights Agreements, in the following
priority: (A) the Registrable Securities requested by the Purchasers to be
included in such registration statement pursuant to this Section 2.1, (B) the
securities proposed to be included by the Company, and then (C) any other
securities of the Company requested to be included in such registration by any
other holder having the right to include securities on a pro rata basis in
accordance with the number of securities proposed to be included by the other
stockholders with such rights.

(c)      Registration Statement Form. Registrations under this Section
2.1 shall be on such appropriate registration form of the Commission as,
subject to clause (a)(i) above, shall be selected by the Company and as shall
be reasonably acceptable to the Purchasers. The Company agrees to include in
any such registration

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statement all information which, in the opinion of counsel to the
Purchasers and counsel to the Company, is necessary or desirable to be included
therein.

(d)      Expenses. The Company shall pay all Registration Expenses in
connection with any registration requested pursuant to this Section 2.1.

(e)      Effective Registration Statement. A registration requested
pursuant to this Section 2.1 shall not be deemed to have been effected
(including for purposes of paragraph (h) of this Section 2.1)
(i) unless a registration statement with respect thereto has become
effective and has been kept continuously effective for a period of at least
365 days (or such shorter period which shall terminate when all the
Registrable Securities covered by such registration statement have been sold
pursuant thereto), (ii) if after it has become effective, such registration
is interfered with by any stop order, injunction or other order or requirement
of the Commission or other governmental agency or court for any reason not
attributable to the Purchasers and has not thereafter become effective, or
(iii) if the conditions to closing specified in the underwriting agreement,
if any, entered into in connection with such registration are not satisfied or
waived.

(f)      Selection of Underwriters. The underwriters of each
underwritten offering of the Registrable Securities so to be registered shall
be selected by the Purchasers, subject to the Companys approval, which
approval shall not be unreasonably withheld.

(g)      Right to Withdraw. If the managing underwriter of any
underwritten offering shall advise the Purchasers that the Registrable
Securities covered by the registration statement cannot be sold in such
offering within a price range acceptable to the Purchasers, then the Purchasers
shall have the right to notify the Company in writing that they have determined
that the registration statement be abandoned or withdrawn, in which event the
Company shall abandon or withdraw such registration statement. In the event of
such abandonment or withdrawal, such request shall not be counted for purposes
of the requests for registration to which the Purchasers are entitled pursuant
to this Section 2.1, and the Purchasers shall pay, or reimburse the Company
for, all Registration Expenses related thereto.

(h)      Limitations on Registration on Request. The
Purchasers shall be entitled to require the Company to effect, and the Company
shall be required to effect, six registrations in the aggregate pursuant to
this Section 2.1.

(i)      Postponement. The Company shall be entitled once in any six-month
period to postpone for a reasonable period of time (but not exceeding 60 days)
(the Postponement Period) the filing of any registration statement required
to be prepared and filed by it pursuant to this Section 2.1 if the Company
determines, in its reasonable judgment, that such registration and offering
would materially interfere with

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any material financing, corporate reorganization or other material
transaction involving the Company or any subsidiary, or would require premature
disclosure thereof, and promptly gives the Purchasers written notice of such
determination, containing a general statement of the reasons for such
postponement (which the Purchasers shall maintain in strict confidence in
accordance with the Confidentiality Agreement (as defined in the Amendment and
Stock Purchase Agreement)) and an approximation of the anticipated delay. If
the Company shall so postpone the filing of a registration statement,
(i) the Company shall use its reasonable best efforts to limit the delay to
as short a period as is practicable and (ii) the Purchasers shall have the
right to withdraw the request for registration by giving written notice to the
Company at any time and, in the event of such withdrawal, such request shall
not be counted for purposes of the requests for registration to which the
Purchasers are entitled pursuant to this Section 2.1.

(j)      Shelf Registration. If the Purchasers request that the Company effect
a registration of Registrable Securities by means of shelf registration
pursuant to Rule 415 under the Securities Act (a Shelf Registration
Statement), in addition to the other requirements contained herein, the
Company shall, at its cost, use its reasonable best efforts to keep the Shelf
Registration Statement continuously effective in order to permit the Prospectus
forming part thereof to be usable by the Purchasers until such time as all the
Registrable Securities covered by the Shelf Registration Statement have been
sold pursuant to the Shelf Registration Statement or cease to be outstanding
(the Effectiveness Period); provided, however, that the Effectiveness Period
in respect of the Shelf Registration Statement shall be extended to the extent
required to permit dealers to comply with the applicable prospectus delivery
requirements under the Securities Act and as otherwise provided herein.

2.2      Incidental Registration.

(a)      Right to Include Registrable Securities. If the
Company at any time proposes to register any of its securities for the account
of any other stockholder under the Securities Act by registration on
Form S-1, S-2 or S-3 or any successor or similar form(s) (except
registrations on any such Form or similar form(s) solely for registration of
securities in connection with an employee benefit plan or dividend reinvestment
plan or a merger or consolidation or incidental to an issuance of securities
under Rule 144A under the Securities Act), it will each such time give prompt
written notice to the Purchasers of its intention to do so and of the
Purchasers rights under this Section 2.2. Upon the written request of the
Purchasers (which request shall specify the maximum number of Registrable
Securities intended to be disposed of by the Purchasers), made as promptly as
practicable and in any event within 30 days after the receipt of any such
notice (10 days if the Company states in such written notice or gives
telephonic notice to the Purchasers, with written confirmation to follow
promptly thereafter, stating that (i) such registration will be on Form S-3
and (ii) such shorter period of time is required because of a planned
filing date), the Company shall use its

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reasonable best efforts to effect the registration under the Securities
Act of all Registrable Securities which the Company has been so requested to
register by the Purchasers; provided, however, that if, at any time after
giving written notice of its intention to register any securities and prior to
the effective date of the registration statement filed in connection with
such registration, the Company shall determine for any reason not
to register or to delay registration of such securities, the Company shall
give written notice of such determination and its reasons therefor (which the
Purchasers will hold in strict confidence in accordance with the
Confidentiality Agreement) to the Purchasers and (i) in the case of a
determination not to register, shall be relieved of its obligation to register
any Registrable Securities in connection with such registration (but not from
any obligation of the Company to pay the Registration Expenses in connection
therewith), without prejudice, however, to the rights of the Purchasers to
request that such registration be effected as a registration under
Section 2.1 and (ii) in the case of a determination to delay
registering, shall be permitted to delay registering any Registrable
Securities, for the same period as the delay in registering such other
securities. No registration effected under this Section 2.2 shall relieve the
Company of its obligation to effect any registration upon request under Section
2.1. The Company will pay all Registration Expenses in connection with any
registration of Registrable Securities requested pursuant to this Section 2.2.

(b)      Right to Withdraw. The Purchasers shall have the right to
withdraw its request for inclusion of its Registrable Securities in any
registration statement pursuant to this Section 2.2 at any time prior to
the execution of an underwriting agreement with respect thereto by giving
written notice to the Company of its request to withdraw.

(c)      Priority in Incidental Registrations. If the managing
underwriter of any underwritten offering shall inform the Company by letter of
its belief that the number of Registrable Securities requested to be included
in such registration, when added to the number of other securities to be
offered in such registration, would materially adversely affect such offering,
then the Company shall include in such registration, to the extent of the
number and type which the Company is so advised can be sold in (or during the
time of) such offering without so materially adversely affecting such offering
(the Section 2.2 Sale Amount) and to the fullest extent permitted by the
terms of the Existing Registration Rights Agreements, in the following
priority: (I) securities proposed to be included by the Company, (II) on a pro
rata basis in accordance with the number of securities proposed to be included
by the stockholders, if any, triggering such incidental registration, the
securities proposed by such stockholders triggering such incidental
registration, and then (III) the Registrable Securities requested by the
Purchasers to be included in such registration pursuant to Section 2.2(a)
and any other securities of the Company requested to be included in such
registration by any other holder having the right to include securities on a
pro rata basis (in an amount in the aggregate equal to the Section 2.2 Sale
Amount), based on the pro rata amount of shares

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of Common Stock held, or obtainable by exercise or conversion of other
securities of the Company, by the Purchasers or such holder.

(d)      Plan of Distribution. Any participation by holders of
Registrable Securities in a registration by the Company shall be in accordance
with the Companys plan of distribution, provided that the Purchasers shall in
consultation with the Company have the right to select a co-managing
underwriter.

2.3      Registration Procedures. If and whenever the Company is required
to use its reasonable best efforts to effect the registration of any
Registrable Securities under the Securities Act as provided in Sections 2.1
and 2.2 hereof, the Company shall as expeditiously as possible:



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| | (a)      prepare and file with the Commission as soon as
practicable the requisite registration statement to effect such
registration (and shall include all financial statements required
by the Commission to be filed therewith) and thereafter use its
reasonable best efforts to cause such registration statement to
become effective; provided, however, that before filing such
registration statement (including all exhibits) or any amendment or
supplement thereto or comparable statements under securities or
blue sky laws of any jurisdiction, the Company shall as promptly as
practicable furnish such documents to the Purchasers and each
underwriter, if any, participating in the offering of the
Registrable Securities and their respective counsel, which
documents will be subject to the review and comments of the
Purchasers, each underwriter and their respective counsel; and
provided, further, however, that the Company may discontinue any
registration of its securities which are not Registrable Securities
at any time prior to the effective date of the registration
statement relating thereto;



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| | (b)      notify the Purchasers of the Commissions requests for
amending or supplementing the registration statement and the
prospectus, and prepare and file with the Commission such
amendments and supplements to such registration statement and the
prospectus used in connection therewith as may be necessary to keep
such registration statement effective and to comply with the
provisions of the Securities Act with respect to the disposition of
all Registrable Securities covered by such registration statement
for such period as shall be required for the disposition of all of
such Registrable Securities in accordance with the intended method
of distribution thereof; provided, that except with respect to any
such registration statement filed pursuant to Rule 415 under
the Securities Act, such period need not exceed 365 days;



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| | (c)      furnish, without charge, to the Purchasers and each
underwriter such number of conformed copies of such registration
statement and of

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| | each such amendment and supplement thereto (in each case
including all exhibits), such number of copies of the prospectus
contained in such registration statement (including each
preliminary prospectus and any summary prospectus) and any other
prospectus filed under Rule 424 under the Securities Act, in
conformity with the requirements of the Securities Act, and such
other documents, as the Purchasers and such underwriters may
reasonably request;



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| | (d)      use its reasonable best efforts (i) to register or
qualify all Registrable Securities and other securities covered by
such registration statement under such securities or blue sky laws
of such States of the United States of America where an exemption
is not available and as the Purchasers or any managing underwriter
shall reasonably request, (ii) to keep such registration or
qualification in effect for so long as such registration statement
remains in effect, and (iii) to take any other action which may
be reasonably necessary or advisable to enable the Purchasers to
consummate the disposition in such jurisdictions of the securities
to be sold by the Purchasers, except that the Company shall not for
any such purpose be required to qualify generally to do business as
a foreign corporation in any jurisdiction wherein it would not but
for the requirements of this subsection (d) be obligated to be
so qualified or to consent to general service of process in any
such jurisdiction;



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| | (e)      use its reasonable best efforts to cause all Registrable
Securities covered by such registration statement to be registered
with or approved by such other federal or state governmental
agencies or authorities as may be necessary in the opinion of
counsel to the Company and counsel to the Purchasers to consummate
the disposition of such Registrable Securities;



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| | (f)      furnish to the Purchasers and each underwriter, if any,
participating in the offering of the securities covered by such
registration statement, a signed counterpart of (i) an opinion
of counsel for the Company, and (ii) a comfort letter signed
by the independent public accountants who have certified the
Companys or any other entitys financial statements included or
incorporated by reference in such registration statement, covering
substantially the same matters with respect to such registration
statement (and the prospectus included therein) and, in the case of
the accountants comfort letter, with respect to events subsequent
to the date of such financial statements, as are customarily
covered in opinions of issuers counsel and in accountants comfort
letters delivered to the underwriters in underwritten public
offerings of securities (and dated the dates such opinions and
comfort letters are customarily dated) and, in the case of the
legal opinion, such other legal matters;

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| | (g)      promptly notify the Purchasers and each managing
underwriter, if any, participating in the offering of the
securities covered by such registration statement (i) when such
registration statement, any pre-effective amendment, the prospectus
or any prospectus supplement related thereto or post-effective
amendment to such registration statement has been filed, and, with
respect to such registration statement or any post-effective
amendment, when the same has become effective; (ii) of any
request by the Commission for amendments or supplements to such
registration statement or the prospectus related thereto or for
additional information; (iii) of the issuance by the Commission
of any stop order suspending the effectiveness of such registration
statement or the initiation of any proceedings for that purpose;
(iv) of the receipt by the Company of any notification with
respect to the suspension of the qualification of any of the
Registrable Securities for sale under the securities or blue sky
laws of any jurisdiction or the initiation of any proceeding for
such purpose; (v) at any time when a prospectus relating
thereto is required to be delivered under the Securities Act, upon
discovery that, or upon the happening of any event as a result of
which, the prospectus included in such registration statement, as
then in effect, includes an untrue statement of a material fact or
omits to state any material fact required to be stated therein or
necessary to make the statements therein not misleading, in the
light of the circumstances under which they were made, and in the
case of this clause (v), at the request of the Purchasers
promptly prepare and furnish to the Purchasers and each managing
underwriter, if any, participating in the offering of the
Registrable Securities, a reasonable number of copies of a
supplement to or an amendment of such prospectus as may be
necessary so that, as thereafter delivered to the purchasers of
such securities, such prospectus shall not include an untrue
statement of a material fact or omit to state a material fact
required to be stated therein or necessary to make the statements
therein not misleading in the light of the circumstances under
which they were made; and (vi) at any time when the
representations and warranties of the Company contemplated by
Section 2.4(a) or (b) hereof cease to be true and correct;



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| | (h)      otherwise comply with all applicable rules and regulations
of the Commission, and make available to its security holders, as
soon as reasonably practicable, an earnings statement covering the
period of at least twelve months beginning with the first full
calendar month after the effective date of such registration
statement, which earnings statement shall satisfy the provisions of
Section 11(a) of the Securities Act and Rule 158 promulgated
thereunder, and promptly furnish to the Purchasers a copy of any
amendment or supplement to such registration statement or
prospectus;

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| | (i)      provide and cause to be maintained a transfer agent and
registrar (which, in each case, may be the Company) for all
Registrable Securities covered by such registration statement from
and after a date not later than the effective date of such
registration;



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| | (j)      (i) use its reasonable best efforts to cause all
Registrable Securities covered by such registration statement to be
listed on the NASDAQ national market system or the principal
securities exchange on which similar securities issued by the
Company are then listed (if any), if the listing of such
Registrable Securities is then permitted under the rules of such
exchange, or (ii) if no similar securities are then so listed,
use its reasonable best efforts to (x) cause all such
Registrable Securities to be listed on a national securities
exchange or (y) failing that, secure designation of all such
Registrable Securities as a NASDAQ national market system
security within the meaning of Rule 11Aa2-1 of the Commission or
(z) failing that, to secure NASDAQ authorization for such
shares and, without limiting the generality of the foregoing, to
arrange for at least two market makers to register as such with
respect to such shares with the National Association of Securities
Dealers, Inc.;



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| | (k)      deliver promptly to counsel to the Purchasers and each
underwriter, if any, participating in the offering of the
Registrable Securities, copies of all correspondence between the
Commission and the Company, its counsel or auditors and all
memoranda relating to discussions with the Commission or its staff
with respect to such registration statement;



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| | (l)      use its reasonable best efforts to obtain the withdrawal
of any order suspending the effectiveness of the registration
statement;



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| | -----------------------------------------------------------------------------------------------------------------------------------
| | (m)      provide a CUSIP number for all Registrable Securities, no
later than the effective date of the registration statement; and



| |                                                                                                                                                                                                                                                                                                           
| | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | (n)      in connection with any underwritten public offering, make
available its senior executive officers, directors and chairman and
otherwise provide reasonable assistance to the underwriters (taking
into account the needs of the Companys business) in their
marketing of Registrable Securities.

The Company may require the Purchasers to furnish the Company such information
regarding the Purchasers and the distribution of the Registrable Securities as
the Company may from time to time reasonably request in writing.

The Purchasers agree that upon receipt of any notice from the Company of
the happening of any event of the kind described in paragraph (g)(iii) or
(v) of this

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Section 2.3, the Purchasers will, to the extent appropriate,
discontinue their disposition of Registrable Securities pursuant to the
registration statement relating to such Registrable Securities until, in the
case of paragraph (g)(v) of this Section 2.3, their receipt of the
copies of the supplemented or amended prospectus contemplated by
paragraph (g)(v) of this Section 2.3 and, if so directed by the
Company, will deliver to the Company (at the Companys expense) all copies,
other than permanent file copies, then in their possession, of the prospectus
relating to such Registrable Securities current at the time of receipt of such
notice. If the disposition by the Purchasers of their securities is
discontinued pursuant to the foregoing sentence, the Company shall extend the
period of effectiveness of the registration statement by the number of days
during the period from and including the date of the giving of notice to and
including the date when the Purchasers shall have received copies of the
supplemented or amended prospectus contemplated by paragraph (g)(v) of this
Section 2.3; and, if the Company shall not so extend such period, the
Purchasers request pursuant to which such registration statement was filed
shall not be counted for purposes of the requests for registration to which the
Purchasers are entitled pursuant to Section 2.1 hereof.

2.4      Underwritten Offerings.

(a)      Requested Underwritten Offerings. If requested by the
underwriters for any underwritten offering by the Purchasers pursuant to a
registration requested under Section 2.1, the Company shall enter into a
customary underwriting agreement (in the form of underwriting agreement used at
such time by the managing underwriter(s)) with a managing underwriter or
underwriters selected by the Purchasers. Such underwriting agreement shall be
satisfactory in form and substance to the Purchasers and shall contain such
representations and warranties by, and such other agreements on the part of,
the Company and such other terms as are generally prevailing in agreements of
the managing underwriter(s), including, without limitation, their customary
provisions relating to indemnification and contribution. The Purchasers shall
be party to such underwriting agreement and may, at their option, require that
any or all of the representations and warranties by, and the other agreements
on the part of, the Company to and for the benefit of such underwriters shall
also be made to and for the benefit of the Purchasers and that any or all of
the conditions precedent to the obligations of such underwriters under such
underwriting agreement be conditions precedent to the obligations of the
Purchasers.

(b)      Incidental Underwritten Offerings. In the case of a
registration pursuant to Section 2.2 hereof, if the Company shall have
determined to enter into any underwriting agreements in connection therewith,
all of the Registrable Securities to be included in such registration shall be
subject to such underwriting agreements. The Purchasers shall be party to such
underwriting agreement and may, at their option, require that any or all of the
representations and warranties by, and the other agreements on the part of, the
Company to and for the benefit of such underwriters shall

-12-



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also be made to and for the benefit of the Purchasers and that any or all
of the conditions precedent to the obligations of such underwriters under such
underwriting agreement be conditions precedent to the obligations of the
Purchasers.

2.5      Preparation; Reasonable Investigation. In connection with the
preparation and filing of each registration statement under the Securities Act
pursuant to this Agreement, the Company will give the Purchasers, their
underwriters, if any, and their respective counsel, accountants and other
representatives and agents the opportunity to participate in the preparation of
such registration statement, each prospectus included therein or filed with the
Commission, and each amendment thereof or supplement thereto, and give each of
them such access to its books and records and such opportunities to discuss the
business of the Company with its officers and employees and the independent
public accountants who have certified its financial statements, and supply all
other information reasonably requested by each of them, as shall be necessary
or appropriate, in the opinion of the Purchasers and such underwriters
respective counsel, to conduct a reasonable investigation within the meaning of
the Securities Act.

2.6      Indemnification.

(a)      Indemnification by the Company. The Company agrees that in
the event of any registration of any securities of the Company under the
Securities Act, the Company shall, and hereby does, indemnify and hold harmless
the Purchasers, their respective directors, officers, members, partners, agents
and affiliates and each other Person who participates as an underwriter in the
offering or sale of such securities and each other Person, if any, who controls
the Purchasers or any such underwriter within the meaning of the Securities
Act, against any losses, claims, damages, or liabilities, joint or several, to
which the Purchasers or any such director, officer, member, partner, agent or
affiliate or underwriter or controlling person may become subject under the
Securities Act or otherwise, insofar as such losses, claims, damages or
liabilities, joint or several (or actions or proceedings, whether commenced or
threatened, in respect thereof), arise out of or are based upon (i) any
untrue statement or alleged untrue statement of any material fact contained in
any registration statement under which such securities were registered under
the Securities Act, any preliminary prospectus, final prospectus or summary
prospectus contained therein, or any amendment or supplement thereto,
(ii) any omission or alleged omission to state therein a material fact
required to be stated therein or necessary to make the statements therein in
light of the circumstances in which they were made not misleading, or
(iii) any violation by the Company of any federal, state or common law rule
or regulation applicable to the Company and relating to action required of or
inaction by the Company in connection with any such registration, and the
Company shall reimburse the Purchasers and each such director, officer, member,
partner, agent or affiliate, underwriter and controlling Person for any legal
or any other expenses reasonably incurred by them in connection with
investigating or defending any such loss, claim, liability, action or
proceeding; provided that the Company shall not be

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liable in any such case to the Purchasers or any such director, officer,
member, partner, agent, affiliate, or controlling person to the extent that any
such loss, claim, damage, liability (or action or proceeding in respect
thereof) or expense arises out of or is based upon an untrue statement or
alleged untrue statement or omission or alleged omission made in such
registration statement, any such preliminary prospectus, final prospectus,
summary prospectus, amendment or supplement in reliance upon and in conformity
with written information furnished to the Company by or on behalf of the
Purchasers, specifically stating that it is for use in the preparation thereof.
Such indemnity shall remain in full force regardless of any investigation made
by or on behalf of the Purchasers or any such director, officer, member,
partner, agent, affiliate, underwriter or controlling Person and shall survive
the transfer of such securities by the Purchasers.

(b)      Indemnification by the Purchasers. As a condition to
including any Registrable Securities in any registration statement, the Company
shall have received an undertaking reasonably satisfactory to it from the
Purchasers so including any Registrable Securities to indemnify and hold
harmless (in the same manner and to the same extent as set forth in paragraph
(a) of this Section 2.6) the Company, and each director of the Company,
each officer of the Company and each other Person, if any, who controls the
Company within the meaning of the Securities Act, with respect to any statement
or alleged statement in or omission or alleged omission from such registration
statement, any preliminary prospectus, final prospectus or summary prospectus
contained therein, or any amendment or supplement thereto, but only to the
extent such statement or alleged statement or omission or alleged omission was
made in reliance upon and in conformity with written information furnished to
the Company by or on behalf of the Purchasers specifically stating that it is
for use in the preparation of such registration statement, preliminary
prospectus, final prospectus, summary prospectus, amendment or supplement;
provided, however, that the liability of such indemnifying party under this
Section 2.6(b) shall be limited to the amount of proceeds (net of expenses and
underwriting discounts and commissions) received by such indemnifying party in
the offering giving rise to such liability. Such indemnity shall remain in
full force and effect, regardless of any investigation made by or on behalf of
the Company or any such director, officer or controlling Person and shall
survive the transfer of such securities by the Purchasers.

(c)      Notices of Claims, etc. Promptly after receipt by an
indemnified party of notice of the commencement of any action or proceeding
involving a claim referred to in the preceding subsections of this Section 2.6,
such indemnified party shall, if a claim in respect thereof is to be made
against an indemnifying party, give written notice to the latter of the
commencement of such action or proceeding; provided, however, that the failure
of any indemnified party to give notice as provided herein shall not relieve
the indemnifying party of its obligations under the preceding subsections of
this Section 2.6, except to the extent that the indemnifying party is
actually prejudiced by such failure to give notice, and shall not relieve the
indemnifying party from any liability

-14-



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which it may have to the indemnified party otherwise than under this
Section 2.6. In case any such action or proceeding is brought against an
indemnified party, the indemnifying party shall be entitled to participate
therein and, unless in the opinion of outside counsel to the indemnified party
a conflict of interest between such indemnified and indemnifying parties may
exist in respect of such claim, to assume the defense thereof, jointly with any
other indemnifying party similarly notified to the extent that it may wish,
with counsel reasonably satisfactory to such indemnified party; provided,
however, that if the defendants in any such action or proceeding include both
the indemnified party and the indemnifying party and if in the opinion of
outside counsel to the indemnified party there may be legal defenses available
to such indemnified party and/or other indemnified parties which are different
from or in addition to those available to the indemnifying party, the
indemnified party or parties shall have the right to select separate counsel to
defend such action or proceeding on behalf of such indemnified party or
parties, provided, however, that the indemnifying party shall be obligated to
pay for only one counsel and one local counsel for all indemnified parties.
After notice from the indemnifying party to such indemnified party of its
election so to assume the defense thereof and approval by the indemnified party
of such counsel, the indemnifying party shall not be liable to such indemnified
party for any legal expenses subsequently incurred by the latter in connection
with the defense thereof other than reasonable costs of investigation (unless
the first proviso in the preceding sentence shall be applicable). No
indemnifying party shall be liable for any settlement of any action or
proceeding effected without its written consent. No indemnifying party shall,
without the consent of the indemnified party (which consent shall not be
unreasonably withheld or delayed), consent to entry of any judgment or enter
into any settlement which does not include as an unconditional term thereof the
giving by the claimant or plaintiff to such indemnified party of a release from
all liability in respect to such claim or litigation.

(d)      Contribution. If the indemnification provided for in this Section 2.6
shall for any reason be held by a court to be unavailable to an indemnified
party under subsection (a) or (b) hereof in respect of any loss, claim,
damage or liability, or any action in respect thereof, then, in lieu of the
amount paid or payable under subsection (a) or (b) hereof, the
indemnified party and the indemnifying party under subsection (a) or
(b) hereof shall contribute to the aggregate losses, claims, damages and
liabilities (including legal or other expenses reasonably incurred in
connection with investigating the same), (i) in such proportion as is
appropriate to reflect the relative fault of the indemnifying party on the one
hand, and the indemnified party on the other, which resulted in such loss,
claim, damage or liability, or action in respect thereof, with respect to the
statements or omissions which resulted in such loss, claim, damage or
liability, or action in respect thereof, as well as any other relevant
equitable considerations, or (ii) if the allocation provided by clause
(i) above is not permitted by applicable law or if the allocation provided
in this clause (ii) provides a greater amount to the indemnified party than
clause (i) above, in such proportion as shall be appropriate to reflect not
only the relative fault but also the relative benefits received by the
indemnifying party and the

-15-



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indemnified party from the offering of the securities covered by such
registration statement as well as any other relevant equitable considerations.
The parties hereto agree that it would not be just and equitable if
contributions pursuant to this Section 2.6(d) were to be determined by pro
rata allocation or by any other method of allocation which does not take into
account the equitable considerations referred to in the preceding sentence of
this Section 2.6(d). No Person guilty of fraudulent misrepresentation
(within the meaning of Section 11(f) of the Securities Act) shall be
entitled to contribution from any Person who was not guilty of such fraudulent
misrepresentation. In addition, no Person shall be obligated to contribute
hereunder any amounts in payment for any settlement of any action or claim
effected without such Persons consent, which consent shall not be unreasonably
withheld. Notwithstanding anything in this subsection (d) to the contrary,
no indemnifying party (other than the Company) shall be required to contribute
any amount in excess of the proceeds (net of expenses and underwriting
discounts and commissions) received by such party from the sale of the
Registrable Securities in the offering to which the losses, claims, damages or
liabilities of the indemnified parties relate.

(e)      Other Indemnification. Indemnification and contribution similar
to that specified in the preceding subsections of this Section 2.6 (with
appropriate modifications) shall be given by the Company and the Purchasers
with respect to any required registration or other qualification of securities
under any federal, state or blue sky law or regulation of any governmental
authority other than the Securities Act. The indemnification agreements
contained in this Section 2.6 shall be in addition to any other rights to
indemnification or contribution which any indemnified party may have pursuant
to law or contract and shall remain operative and in full force and effect
regardless of any investigation made by or on behalf of any indemnified party
and shall survive the transfer of any of the Registrable Securities by the
Purchasers.

(f)      Indemnification Payments. The indemnification and contribution
required by this Section 2.6 shall be made by periodic payments of the amount
thereof during the course of the investigation or defense, as and when bills
are received or expense, loss, damage or liability is incurred.

2.7      Unlegended Certificates. In connection with the offering of any
Registrable Securities registered pursuant to this Section 2, the Company
shall (i) facilitate the timely preparation and delivery to the Purchasers
and the underwriters, if any, participating in such offering, of unlegended
certificates representing ownership of such Registrable Securities being sold
in such denominations and registered in such names as requested by the
Purchasers or such underwriters and (ii) instruct any transfer agent and
registrar of such Registrable Securities to release any stop transfer orders
with respect to any such Registrable Securities.

2.8      Manner of Sale. So long as the Purchasers own in excess of 2.5% of
the fully diluted Common Stock (after giving effect to the exercise of all

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outstanding options, warrants and other rights to purchase Common Stock
whether or not such options, warrants or other rights are then exercisable (the
Threshold Amount)), the Purchasers agree that, except as provided below or
except with the written consent of the Company (which consent shall not be
unreasonably withheld), the Purchasers shall sell or otherwise effectuate a
distribution of Registrable Securities included in a registration effected
pursuant to Section 2.1 or in a registration effected by the Company for
its own account in which the Purchasers elect, pursuant to Section 2.2, to
include Registrable Securities, only (i) pursuant to one or more firm
commitment underwritten public offerings or (ii) in one or more block trades.
Notwithstanding anything to the contrary set forth above, at any time while the
Purchasers own an amount of Common Stock in excess of the Threshold Amount, the
Purchasers shall have the right to effectuate a distribution of Registrable
Securities included in a registration effected pursuant to Section 2.1 or
in a registration effected by the Company for its own account in which the
Purchasers elect, pursuant to Section 2.2, to include Registrable Securities,
in any other manner, including pursuant to a Shelf Registration Statement, if
in the opinion of a nationally recognized investment banker selected by the
Company and the Purchasers, distributions of Registrable Securities made in the
manner proposed by the Purchasers would not adversely affect the market for the
Common Stock. Nothing contained herein shall be deemed to restrict the
Purchasers from transferring any of the Common Stock at any time. In the event
the Purchasers elect, pursuant to Section 2.2, to include Registrable
Securities in any registration effected by the Company for the account of any
other stockholder triggering such registration, the Purchasers shall sell or
otherwise effectuate a distribution of Registrable Securities pursuant to such
registration subject to the same manner of sale limitations as are applicable
to such other stockholder in such registration.

2.9      No Required Sale. Nothing in this Agreement shall be deemed
to create an independent obligation on the part of the Purchasers to sell any
Registrable Securities pursuant to any effective registration statement.

3.      Rule 144. The Company shall take all actions reasonably necessary
to enable holders of Registrable Securities to sell such securities without
registration under the Securities Act within the limitation of the exemptions
provided by (i) Rule 144, or (ii) any similar rule or regulation
hereafter adopted by the Commission including, without limiting the generality
of the foregoing, filing on a timely basis all reports required to be filed by
the Exchange Act. Upon the request of the Purchasers, the Company will deliver
to such holder a written statement as to whether it has complied with such
requirements.

4.      Amendments and Waivers. This Agreement may be amended,
modified or supplemented only by written agreement of the party against whom
enforcement of such amendment, modification or supplement is sought.

5.      [INTENTIONALLY OMITTED].

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6.      Notice. All notices and other communications hereunder shall be in
writing and, unless otherwise provided herein, shall be deemed to have been
given when received by the party to whom such notice is to be given at its
address set forth below, or such other address for the party as shall be
specified by notice given pursuant hereto:

|    |  |                                         
|--- |  | ----------------------------------------
|(a) |  | If to the Purchasers, to:               
|   
|   
|   
|   
|   
|    |  | c/o Forstmann Little & Co.              
|   
|   
|   
|   
|    |  | 767 Fifth Avenue                        
|   
|   
|   
|   
|    |  | New York, NY 10153                      
|   
|   
|   
|   
|    |  | Attention: Sandra J. Horbach            
|   
|   
|   
|   
|   
|    |  | With a copy to:                         
|   
|   
|   
|   
|   
|    |  | Fried, Frank, Harris, Shriver & Jacobson
|   
|   
|   
|   
|    |  | One New York Plaza                      
|   
|   
|   
|   
|    |  | New York, NY 10004                      
|   
|   
|   
|   
|    |  | Attention: Robert C. Schwenkel, Esq.    
|   
|   
|   
|   
|   
|(b) |  | If to the Company, to it at:            
|   
|   
|   
|   
|   
|    |  | XO Communications, Inc.                 
|   
|   
|   
|   
|    |  | 11111 Sunset Hills Road                 
|   
|   
|   
|   
|    |  | Reston, VA 20190                        
|   
|   
|   
|   
|    |  | Attn: Gary D. Begeman, Esq.             
|   
|   
|   
|   
|   
|    |  | with a copy to:                         
|   
|   
|   
|   
|   
|    |  | Willkie Farr & Gallagher                
|   
|   
|   
|   
|    |  | 787 Seventh Avenue                      
|   
|   
|   
|   
|    |  | New York, NY 10019                      
|   
|   
|   
|   
|    |  | Attn: Bruce R. Kraus, Esq.              

7.      Assignment; Third Party Beneficiaries. This Agreement shall be binding
upon and inure to the benefit of and be enforceable by the parties hereto and
their respective successors and permitted assigns. This Agreement may not be
assigned by the Company, without the prior written consent of the Purchasers.
The Purchasers may, at their election, at any time or from time to time, assign
their rights under this Agreement, in whole or in part, to any Affiliate (as
defined in the Amendment and Stock Purchase Agreement) or any purchaser or
other transferee of shares of Common Stock held by them; provided, however,
that any rights to withdraw shares from inclusion in a registration statement
pursuant to Section 2 shall be made only by the Purchasers for themselves and
all such purchasers and transferees; and provided further, that no such

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assignment will increase the total number of registrations pursuant to
Section 2.1 or underwritten offerings the Company is required to effect
hereunder.

8.      Remedies. The parties hereto agree that money damages or other remedy
at law would not be sufficient or adequate remedy for any breach or violation
of, or a default under, this Agreement by them and that, in addition to all
other remedies available to them, each of them shall be entitled to an
injunction restraining such breach, violation or default or threatened breach,
violation or default and to any other equitable relief, including without
limitation specific performance, without bond or other security being required.
In any action or proceeding brought to enforce any provision of this Agreement
(including the indemnification provisions thereof), the successful party shall
be entitled to recover reasonable attorneys fees in addition to its costs and
expenses and any other available remedy.

9.      No Inconsistent Agreements. The Company will not, on or after
the date of this Agreement, enter into any agreement with respect to its
securities which is inconsistent with the rights granted to the Purchasers in
this Agreement or otherwise conflicts with the provisions hereof. The Company
further represents and warrants that the rights granted to the Purchasers
hereunder do not in any way conflict with and are not inconsistent with any
other agreements to which the Company is a party or by which it is bound.

10.      Descriptive Headings. The descriptive headings of the several
sections and paragraphs of this Agreement are inserted for reference only and
shall not control or otherwise affect the meaning hereof.

11.      Governing Law. This Agreement shall be construed and enforced in
accordance with, and the rights and obligations of the parties hereto shall be
governed by, the laws of the State of New York, without giving effect to
the conflicts of law principles thereof. Each of the parties hereto hereby
irrevocably and unconditionally consents to submit to the exclusive
jurisdiction of the courts of the State of New York and the United States
of America located in the County of New York for any action or proceeding
arising out of or relating to this Agreement and the transactions contemplated
hereby (and agrees not to commence any action or proceeding relating thereto
except in such courts), and further agrees that service of any process,
summons, notice or document by U.S. registered mail to its respective address
set forth in Section 6 hereof shall be effective service of process for any
action or proceeding brought against it in any such court. Each of the parties
hereto hereby irrevocably and unconditionally waives any objection to the
laying of venue of any action or proceeding arising out of this Agreement or
the transactions contemplated hereby in the courts of the State of New York
or the United States of America located in the County of New York, and
hereby further irrevocably and unconditionally waives and agrees not to plead
or claim in any such court that any such action or proceeding brought in any
such court has been brought in an inconvenient forum.

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12.      Counterparts. This Agreement may be executed in any number of
counterparts, each of which shall be deemed an original, but all such
counterparts shall together constitute one and the same instrument.

13.      Invalidity of Provision. The invalidity or unenforceability
of any provision of this Agreement in any jurisdiction shall not affect the
validity or enforceability of the remainder of this Agreement in that
jurisdiction or the validity or enforceability of this Agreement, including
that provision, in any other jurisdiction. If any restriction or provision of
this Agreement is held unreasonable, unlawful or unenforceable in any respect,
such restriction or provision shall be interpreted, revised or applied in a
manner that renders it lawful and enforceable to the fullest extent possible
under law.

14.      Further Assurances. Each party hereto shall do and perform or
cause to be done and performed all further acts and things and shall execute
and deliver all other agreements, certificates, instruments, and documents as
any other party hereto reasonably may request in order to carry out the intent
and accomplish the purposes of this Agreement and the consummation of the
transactions contemplated hereby.

15.      Entire Agreement; Effectiveness. This Agreement constitutes
the entire agreement, and supersedes all prior agreements and understandings
(including, without limitation, the Existing Registration Rights Agreement),
oral and written, between the parties hereto with respect to the subject matter
hereof.

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IN WITNESS WHEREOF, the parties have caused this Agreement to be executed
and delivered by their respective officers thereunto duly authorized.

|                                                                                           
|-------------------------------------------------------------------------------------------
|XO COMMUNICATIONS, INC                                                                     
|                                                                                           
|                                                                                           
|By:  /s/ Daniel F. Akerson                                                                 
|                                                                                           
|Name:  Daniel F. Akerson
Title: Chairman and Chief Executive
Officer                       
|                                                                                           
|PURCHASERS:                                                                                
|                                                                                           
|FORSTMANN LITTLE & CO. SUBORDINATED DEBT AND
EQUITY MANAGEMENT BUYOUT PARTNERSHIP-VII, L.P.
|                                                                                           
|                                                                                           
|By:  FLC XXXIII Partnership
its general partner                                            
|                                                                                           
|By:  /s/ Winston W. Hutchins                                                               
|                                                                                           
|Winston W. Hutchins,
a general partner                                                     
|                                                                                           
|FORSTMANN LITTLE & CO. EQUITY
PARTNERSHIP-VI, L.P.                                         
|                                                                                           
|By:  FLC XXXII Partnership, L.P.
its general partner                                       
|                                                                                           
|                                                                                           
|By:  /s/ Winston W. Hutchins                                                               
|                                                                                           
|Winston W. Hutchins,
a general partner                                                     

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|                                                   
|---------------------------------------------------
|                                                   
|FL FUND, L.P.                                      
|                                                   
|By:  FLC XXXI Partnership, L.P.
its general partner
|                                                   
|By:  FLC XXIX Partnership, L.P.
a general partner  
|                                                   
|                                                   
|By:  /s/ Winston W. Hutchins                       
|                                                   
|Winston W. Hutchins,
a general partner             

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