ALASKA COMMUNICATIONS SYSTEMS HOLDINGS, INC.

                               OFFER TO EXCHANGE
                   9 3/8% SENIOR SUBORDINATED NOTES DUE 2009
    WHICH HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
                           FOR ALL OF ITS OUTSTANDING
                   9 3/8% SENIOR SUBORDINATED NOTES DUE 2009
             THAT WERE ISSUED AND SOLD IN A TRANSACTION EXEMPT FROM
                     REGISTRATION UNDER THE SECURITIES ACT

To Securities Dealers, Commercial Banks,
Trust Companies and Other Nominees:

    Enclosed for your consideration is a Prospectus dated        , 1999 (as the
same may be amended or supplemented from time to time, the "Prospectus") and a
form of Letter of Transmittal (the "Letter of Transmittal") relating to the
offer (the "Exchange Offer") by Alaska Communications Systems Holdings, Inc.
("ACS") to exchange up to $150,000,000 in aggregate principal amount of its
9 3/8% Senior Subordinated Notes due 2009 which have been registered under the
Securities Act, as amended (the "Exchange Notes"), for up to $150,000,000 in
aggregate principal amount of its outstanding 9 3/8% Senior Subordinated Notes
due 2009 that were issued and sold in a transaction exempt from registration
under the Securities Act of 1933, as amended (the "Old Notes").

    We are asking you to contact your clients for whom you hold Old Notes
registered in your name or in the name of your nominee. In addition, we ask you
to contact your clients who, to your knowledge, hold Old Notes registered in
their old name. ACS will not pay any fees or commissions to any broker, dealer
or other person in connection with the solicitation of tenders pursuant to the
Exchange Offer. You will, however, be reimbursed by ACS for customary mailing
and handling expenses incurred by you for forwarding any of the enclosed
materials to your clients. ACS will pay all transfer taxes, if any, applicable
to the tender of Old Notes to it or its order, except as otherwise provided in
the Prospectus and the Letter of Transmittal.

    Enclosed are copies of the following documents:

    1. the Prospectus;

    2. a Letter of Transmittal for your use in connection with the exchange of
Old Notes and for the information of your clients (facsimile copies of the
Letter of Transmittal may be used to exchange Old Notes);

    3. a form of letter that may be sent to your clients for whose accounts you
hold Old Notes registered in your name or the name of your nominee, with space
provided for obtaining the clients' instructions with regard to the Exchange
Offer;

    4. a Notice of Guaranteed Delivery;

    5. guidelines of the Internal Revenue Service for Certification of Taxpayer
Identification Number on Substitute Form W-9; and

    6. a return envelope addressed to IBJ Whitehall Bank & Trust Company, the
Exchange Agent.

    YOUR PROMPT ACTION IS REQUESTED. THE EXCHANGE OFFER WILL EXPIRE AT 5:00
P.M., NEW YORK CITY TIME, ON       , 1999, UNLESS EXTENDED (THE "EXPIRATION
DATE"). OLD NOTES TENDERED PURSUANT TO THE EXCHANGE OFFER MAY BE WITHDRAWN,
SUBJECT TO THE PROCEDURES DESCRIBED IN THE PROSPECTUS, AT ANY TIME PRIOR TO THE
EXPIRATION DATE.

    To tender Old Notes, certificates for Old Notes or a book-entry confirmation
(see "The Exchange Offer" in the Prospectus), a duly executed and properly
completed Letter of Transmittal or a facsimile thereof, and any other required
documents, must be received by the Exchange Agent as provided in the Prospectus
and the Letter of Transmittal.

    Questions and requests for assistance with respect to the Exchange Offer or
requests for additional copies of the enclosed material may be directed to the
Exchange Agent at its address set forth in the Prospectus or at (212) 858-2103.

                                          Very truly yours,

                                          ALASKA COMMUNICATIONS SYSTEMS
                                          HOLDINGS, INC.

    NOTHING CONTAINED HEREIN OR IN THE ENCLOSED DOCUMENTS SHALL CONSTITUTE YOU
OR ANY OTHER PERSON AS AN AGENT OF ACS OR THE EXCHANGE AGENT, OR ANY AFFILIATE
THEREOF, OR AUTHORIZE YOU OR ANY OTHER PERSON TO MAKE ANY STATEMENTS OR USE ANY
DOCUMENT ON BEHALF OF ANY OF THEM WITH RESPECT TO THE EXCHANGE OFFER, EXCEPT FOR
THE ENCLOSED DOCUMENTS AND THE STATEMENTS EXPRESSLY MADE IN THE PROSPECTUS AND
THE LETTER OF TRANSMITTAL.

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