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                                                                   EXHIBIT 10.24

                  ALASKA COMMUNICATIONS SYSTEMS HOLDINGS, INC.

                                     Issuer

                                   GUARANTORS

                                       and

                              THE BANK OF NEW YORK

                                    Trustee

                             SUPPLEMENTAL INDENTURE

                            Dated as of July 15, 2005

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

                          9 7/8% SENIOR NOTES DUE 2011


Supplemental Indenture July 15, 2005

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            THIS SUPPLEMENTAL INDENTURE (the "Supplemental Indenture"), dated as
of July 15, 2005, is made by and among ALASKA COMMUNICATIONS SYSTEMS HOLDINGS,
INC., a Delaware corporation, (the "Issuer"), ALASKA COMMUNICATIONS SYSTEMS
GROUP, INC., ACS OF THE NORTHLAND, INC., ACS OF ALASKA, INC., ACS OF FAIRBANKS,
INC., ACS OF ANCHORAGE, INC., ACS WIRELESS, INC., ACS INTERNET, INC., ACS
MESSAGING, INC., ACS INFOSOURCE, INC., ACS OF ALASKA LICENSE SUB, INC., ACS OF
THE NORTHLAND LICENSE SUB, INC., ACS OF FAIRBANKS LICENSE SUB, INC., ACS OF
ANCHORAGE LICENSE SUB, INC., ACS WIRELESS LICENSE SUB, INC., ACS LONG DISTANCE
LICENSE SUB, INC., ACS TELEVISION LICENSE SUB, INC., ACS SERVICES, INC. AND ACS
LONG DISTANCE, INC. (collectively, the "Guarantors") and THE BANK OF NEW YORK,
as Trustee (the "Trustee"), under the Indenture dated as of August 26, 2003 (as
amended through the date hereof, the "Indenture"). Capitalized terms used herein
and not otherwise defined shall have the meaning assigned to them in the
Indenture.

                                   WITNESSETH:

            WHEREAS, the Issuer has issued its 9 7/8% Senior Notes Due 2011 (the
"Notes") pursuant to the Indenture;

            WHEREAS, pursuant to Section 9.01(i) of the Indenture, the Issuer,
the Guarantors and the Trustee may amend the Indenture without notice to or
consent of any Holder to oure any ambiguity, omission, detect or inconsistency;

            WHEREAS, the Issuer, the Guarantors and the Trustee desire to amend
the Indenture to cure certain ambiguities, omissions, defects and
inconsistencies;

            WHEREAS, the Issuer has heretofore delivered or is delivering
contemporaneously herewith to the Trustee (i) a copy of resolutions of the Board
of Directors of the Issuer, certified by the Secretary or an Assistant Secretary
of the Issuer, authorizing the execution, delivery and performance of this
Supplemental Indenture, (ii) a copy of resolutions of the Boards of Directors of
each of the Guarantors, certified by the Secretary or an Assistant Secretary of
each of the Guarantors, authorizing the execution, delivery and performance of
this Supplemental Indenture, and (iii) an Officers' Certificate or an Opinion of
Counsel with and to the effect set forth in Section 7.02(b) of the Indenture;

            WHEREAS, all conditions necessary to authorize the execution and
delivery of this Supplemental Indenture and to make this Supplemental Indenture
valid and binding have been complied with or have been done or performed; and

            NOW, THEREFORE, in consideration of the foregoing, the parties
hereto agree as follows.

                                   ARTICLE ONE

Supplemental Indenture July 15, 2005

                                        2
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                                   AMENDMENTS

            SECTION 1.01. Amendments. Subject to Section 2.01 hereof, Section
4.03 of the Indenture is amended and restated in its entirety with the
following:

            "SECTION 4.03. LIMITATION ON INDEBTEDNESS. (a) The Issuer shall not,
      and shall not permit any Restricted Subsidiary to, Incur any Indebtedness;
      PROVIDED, HOWEVER, that the Issuer or any Restricted Subsidiary may Incur
      Indebtedness if on the date of such Incurrence and after giving effect
      thereto the Debt to EBITDA Ratio would be less than 6:1; PROVIDED FURTHER,
      HOWEVER, that, if such Indebtedness proposed to be Incurred pursuant to
      the preceding proviso is Senior Indebtedness, such Senior Indebtedness may
      not be Incurred unless on the date of such Incurrence and after giving
      effect thereto the Senior Debt to EBITDA Ratio would be less than 4.5:1.

            (b) Notwithstanding the foregoing paragraph (a), the Issuer and its
      Restricted Subsidiaries may Incur the following Indebtedness:

                  (i) Bank Indebtedness in an aggregate principal amount not to
            exceed the sum of (1) with respect to a revolving credit facility,
            up to $50,000,000 and (2) with respect to any term loan facilities,
            up to an amount equal to the greater of (a) $335,000,000 and (b) the
            Term Loan Borrowing Base less the aggregate amount of all
            prepayments of principal applied to permanently reduce any such
            Indebtedness; provided, however, that Bank Indebtedness to be
            incurred under clause (2) above in excess of $335,000,000 may only
            be incurred if, after giving effect to such Incurrence, the Senior
            Debt to EBITDA Ratio would be less than 4.5:1;

                  (ii) Indebtedness of the Issuer owed to and held by any Wholly
            Owned Subsidiary or Indebtedness of a Restricted Subsidiary owed to
            and held by the Issuer or any Wholly Owned Subsidiary; PROVIDED,
            HOWEVER, that (1) any subsequent issuance or transfer of any Capital
            Stock or any other event that results in any such Wholly Owned
            Subsidiary ceasing to be a Wholly Owned Subsidiary or any subsequent
            transfer of any such Indebtedness (except to the Issuer or a Wholly
            Owned Subsidiary) shall be deemed, in each case, to constitute the
            Incurrence of such Indebtedness by the issuer thereof and (2) if the
            Issuer is the obligor on such Indebtedness, such Indebtedness is
            expressly subordinated to the prior payment in full in cash of all
            obligations with respect to the Securities;

                  (iii) Indebtedness (1) represented by the Securities (not
            including any Additional Securities) and the Guarantees, (2)
            outstanding on the Closing Date (other than the Indebtedness
            described in clauses (i) and (ii) above), (3) consisting of
            Refinancing Indebtedness Incurred in respect of any Indebtedness
            described in this clause (iii) (including Indebtedness Refinancing
            Indebtedness) or Section 4.03 (a) or (4) consisting of guarantees of
            any Indebtedness permitted under clauses (i) and (ii) of this
            paragraph (b);

Supplemental Indenture July 15, 2005

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                  (iv) (1) Indebtedness of a Restricted Subsidiary Incurred and
            outstanding on or prior to the date on which such Restricted
            Subsidiary was acquired by the Issuer (other than Indebtedness
            Incurred as consideration in, or to provide all or any portion of
            the funds or credit support utilized to consummate, the transaction
            or series of related transactions pursuant to which such Restricted
            Subsidiary became a Subsidiary of, or was otherwise acquired by,
            the Issuer); PROVIDED, HOWEVER, that on the date that such
            Restricted Subsidiary is acquired by the Issuer, the Issuer would
            have been able to Incur $1.00 of additional Indebtedness pursuant
            to Section 4.03(a) after giving effect to the Incurrence of such
            Indebtedness pursuant to this clause (iv) and (2) Refinancing
            Indebtedness Incurred by the Issuer or a Restricted Subsidiary in
            respect of Indebtedness Incurred pursuant to this clause (iv);

                  (v) Indebtedness in respect of performance bonds, bankers'
            acceptances, letters of credit and surely or appeal bonds provided
            by the Issuer and the Restricted Subsidiaries in the ordinary course
            of their business;

                  (vi) Purchase Money Indebtedness and Capitalized Lease
            Obligations in an aggregate principal amount not in excess of
            $20,000,000 at any time outstanding;

                  (vii) Hedging Obligations of the Issuer or any Guarantor
            directly related to Indebtedness permitted to be Incurred by the
            Issuer or any Guarantor pursuant to the Indenture for the purpose of
            fixing or hedging interest rate risk or currency fluctuations; or

                  (viii) (1) Indebtedness of another Person Incurred and
            outstanding on or prior to the date on which such Person
            consolidates with or merges with or into the Issuer (other than
            Indebtedness Incurred as consideration in, or to provide all or any
            portion of the funds or credit support utilized to consummate, the
            transaction or series of related transactions pursuant to which such
            Person consolidates with or merges with or into the Issuer);
            PROVIDED, HOWEVER, that on the date that such transaction is
            consummated, the Issuer would have been able to Incur $1.00 of
            additional Indebtedness pursuant to Section 4.03(a) after giving
            effect to the Incurrence of such Indebtedness pursuant to this
            clause (viii) and (2) Refinancing Indebtedness Incurred by the
            Issuer or the Successor Issuer in respect of Indebtedness Incurred
            pursuant to subclause (1) of this clause (viii).

            (c) Notwithstanding the foregoing, the Issuer shall not Incur any
Indebtedness pursuant to Section 4.03(b) above if the proceeds thereof are used,
directly or indirectly, to repay, prepay, redeem, defease, retire, refund or
refinance any Subordinated Obligations, unless such Indebtedness shall be
subordinated to the Securities to at least the same extent as such Subordinated
Obligations.

            (d) Notwithstanding any other provision of this Section 4.03, the
maximum amount of Indebtedness that the Issuer or any Restricted Subsidiary may
Incur pursuant to this Section 4.03 shall not be deemed to be exceeded solely as
a result of fluctuations in

Supplemental Indenture July 15, 2005
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      the exchange rates of currencies. For purposes of determining the
      outstanding principal amount of any particular Indebtedness Incurred
      pursuant to this Section 4.03:

                  (i) Indebtedness Incurred pursuant to the Credit Agreement
            prior to or on the Closing Date shall be treated as Incurred
            pursuant to Section 4.03(b)(i);

                  (ii) Indebtedness permitted by this Section 4.03 need not be
            permitted solely by reference to one provision permitting such
            Indebtedness but may be permitted in part by one such provision and
            in part by one or more other provisions of this Section 4.03
            permitting such Indebtedness; and

                  (iii) in the event that Indebtedness meets the criteria of
            more than one of the types of indebtedness described in this Section
            4.03, the Issuer, in its sole discretion, shall classify such
            Indebtedness and only be required to include the amount of such
            Indebtedness in one of such clauses."

                                  MISCELLANEOUS

            SECTION 2.01. Effectiveness. This Supplemental Indenture shall
become effective on and as of the date the counterparts hereto shall have been
executed and delivered by each of the parties hereto.

            SECTION 2.02. GOVERNING LAW. THE INTERNAL LAW OF THE STATE OF NEW
YORK, INCLUDING WITHOUT LIMITATION, SECTION 5-1401 OF THE NEW YORK GENERAL
OBLIGATIONS LAW, SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL
SUPPLEMENTAL INDENTURE.

            SECTION 2,03. Counterparts. This Supplemental Indenture may be
executed in any number of counterparts, each of which shall be an original; but
such counterparts shall constitute but one and the same instrument.

            SECTION 2.04. Severability. In case any provision of this
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby.

            SECTION 2.05. Ratification. Except as expressly waived, amended or
supplemented hereby, all of the terms of the Indenture shall remain and continue
in full force and effect and are hereby confirmed in all respects and, as
expressly waived, amended, or supplemented hereby, the Indenture is in all
respects agreed to, ratified and confirmed by each of the Issuer, the Guarantors
and the Trustee.

            SECTION 2.06. Trustee. The Trustee accepts the trusts created by the
Indenture, as supplemented by this Supplemental Indenture, and agrees to perform
the same upon the terms and conditions of the Indenture, as amended and
supplemented by this Supplemental Indenture.

            SECTION 2.07. No Representations by Trustee. The recitals contained
herein shall be taken as the statement of the Issuer and Guarantors, and the
Trustee assumes no responsibility whatsoever for their correctness. The Trustee
makes no representations as to the validity or sufficiency of this Supplemental
Indenture or for the due execution hereof by the Issuer and the Guarantors.

SUPPLEMENTAL INDENTURE JULY 15, 2005
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            SECTION 2.08. Reaffirmation. The parties hereto make and reaffirm as
of the date of execution of this Supplemental Indenture all of their respective
representations, covenants and agreements set forth in the Indenture, as amended
by this Supplemental Indenture.

            SECTION 2.09. Assignment. All covenants and agreements of the
Issuer, the Guarantors, and the Trustee in the Indenture, as amended by this
Supplemental Indenture, shall bind each of their respective Successors and
assigns, whether so expressed or not.

            SECTION 2.10. Third-Party Beneficiaries. Nothing in this
Supplemental Indenture, express or implied, shall give to any Person, other than
the parties hereto and their successors under the Indenture and the Holders of
the Notes, any benefit or any legal or equitable right, remedy or claim under
the Indenture or this Supplemental Indenture.

            SECTION 2.11. Trust Indenture Act. If any provisions hereof limit,
quality or conflict with a provision of the Trust Indenture Act of 1939, as
amended from time to time (the "TIA"), required under the TIA to be a part of
and govern this Supplemental Indenture, the provisions of the TIA shall control.
If any provision hereof modifies or excludes any provision of the TIA that may
be so modified or excluded, the latter provisions shall be deemed to apply to
this Supplemental Indenture as so modified or excluded, as the case may be.

            SECTION 2.12. Unity. All provisions of this Supplemental Indenture
shall be deemed to be incorporated in, and made a part of, the Indenture. The
Indenture, as amended and supplemented by this Supplemental Indenture, shall be
read, taken and construed as one and the same instrument.

                            (signature pages follow)

Supplemental Indenture July 15, 2005


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            IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed all as of the date and year first above written.

                                ALASKA COMMUNICATIONS SYSTEMS GROUP, INC.

                                By: /s/ David Wilson
                                    --------------------------------------------
                                    Name: David Wilson
                                    Title: Senior Vice President and
                                           Chief Financial Officer

                                ALASKA COMMUNICATIONS SYSTEMS GROUP, INC.

                                By: /s/ David Wilson
                                    --------------------------------------------
                                    Name: David Wilson
                                    Title: Senior Vice President and
                                           Chief Financial Officer

                                ACS OF THE NORTHLAND, INC.
                                ACS OF ALASKA, INC.
                                ACS OF FAIRBANKS, INC.
                                ACS OF ANCHORAGE, INC.
                                ACS WIRELESS, INC.
                                ACS INTERNET, INC.
                                ACS MESSAGING, INC.
                                ACS INFOSOURCE, INC.
                                ACS OF ALASKA LICENSE SUB, INC.
                                ACS OF THE NORTHLAND LICENSE SUB, INC.
                                ACS OF FAIRBANKS LICENSE SUB, INC.
                                ACS OF ANCHORAGE LICENSE SUB, INC.
                                ACS WIRELESS LICENSE SUB, INC.
                                ACS LONG DISTANCE LICENSE SUB, INC.
                                ACS TELEVISION LICENSE SUB, INC.
                                ACS SERVICES, INC.
                                ACS LONG DISTANCE, INC.

                                By: /s/ David Wilson
                                    --------------------------------------------
                                    Name: David Wilson
                                    Title: Senior Vice President and
                                           Chief Financial Officer

Supplemental Indenture July 15, 2005
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                               THE BANK OF NEW YORK

                               BY: /s/ Sandie Parks
                                   ---------------------------------------------
                                   Name: Sandie Parks
                                   Title: Vice President