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Exhibit 10.28

CONVERTIBLE NOTE BETWEEN ERF WIRELESS, INC., IN FAVOR OF AND GCA STRATEGIC
INVESTMENT FUND LIMITED


THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE UNITED
STATES SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"). THE HOLDER
HEREOF, BY PURCHASING SUCH SECURITIES AGREES FOR THE BENEFIT OF THE COMPANY THAT
SUCH SECURITIES MAY BE OFFERED, SOLD OR OTHERWISE TRANSFERRED ONLY (A) TO THE
COMPANY, (B) PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES
ACT, OR (C) IF REGISTERED UNDER THE SECURITIES ACT AND ANY APPLICABLE STATE
SECURITIES LAWS. IN ADDITION, A SECURITIES PURCHASE AGREEMENT, DATED AS OF THE
DATE HEREOF, A COPY OF WHICH MAY BE OBTAINED FROM THE COMPANY AT ITS PRINCIPAL
EXECUTIVE OFFICE, CONTAINS CERTAIN ADDITIONAL AGREEMENTS AMONG THE PARTIES,
INCLUDING, WITHOUT LIMITATION, PROVISIONS WHICH (A) LIMIT THE CONVERSION RIGHTS
OF THE HOLDER, (B) SPECIFY VOLUNTARY AND MANDATORY REPAYMENT, PREPAYMENT AND
REDEMPTION RIGHTS AND OBLIGATIONS AND (C) SPECIFY EVENTS OF DEFAULT FOLLOWING
WHICH THE REMAINING BALANCE DUE AND OWING HEREUNDER MAY BE ACCELERATED.


No. 1                                                                 $50,000

                            SECURED CONVERTIBLE NOTE
                                       of
                               ERF Wireless, Inc.

         ERF Wireless, Inc., a Nevada corporation (together with its successors,
the "Company"), for value received hereby promises to pay to:


                     GCA STRATEGIC INVESTMENT FUND LIMITED


(the "Holder") and registered assigns, the principal sum of Fifty Thousand
Dollars ($50,000) or, if less, the principal amount of this Note then
outstanding, on the Maturity Date by wire transfer of immediately available
funds to the Holder in such coin or currency of the United States of America as
at the time of payment shall be legal tender for the payment of public and
private debts, and to pay interest, which shall begin to accrue on the date of
this Secured Note ("Note"), quarterly in arrears, on (i) the last day of March,
June, September and December of each year until the Maturity Date, commencing
September 30, 2005 (unless such day is not a Business Day, in which event on the
next succeeding Business Day) (each an "Interest Payment Date"), (ii) the
Maturity Date, and (iii) the date the principal amount of the Note shall be
declared to be or shall automatically become due and payable, on the principal
sum hereof outstanding in like coin or currency, at the rates per annum set
forth below, from the most recent Interest Payment Date to which interest has
been paid on this Note, or if no interest has been paid on this Note, from the
date of this Note until payment in full of the principal sum hereof has been
made.

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         The interest rate shall be six percent (6%) per annum (the "Interest
Rate") or, if less, the maximum rate permitted by applicable law. At the option
of the Company, interest may be paid in cash or in shares of Common Stock. The
number of shares of Common Stock issued as interest shall be determined by
dividing the dollar amount of interest due on the applicable Interest Payment
Date by the Market Price then in effect. "Market Price" shall mean the VWAP for
the Common Stock as reported by Bloomberg, L.P., for five trading days
immediately prior to the date such interest becomes due. Past due amounts
(including interest, to the extent permitted by law) will also accrue interest
at the Interest Rate plus 4% per annum or, if less, the maximum rate permitted
by applicable law, and will be payable on demand (`Default Interest"). Interest
on this Note will be calculated on the basis of a 360-day year of twelve 30 day
months. All payments of principal and interest hereunder shall be made for the
benefit of the Holder pursuant to the terms of the Agreement (hereafter
defined).

         This Note (this "Note") is secured by a Security Agreement (the
"Security Agreement") of even date herewith made by the Company (or one of its
subsidiaries, as applicable) and Holder creating a security interest in favor of
Holder in certain of the assets described in the Security Agreement (the
"Collateral").

         This Note is a duly authorized issuance of $1,285,000.00 aggregate
principal amount of Notes of the Company dated as of the date hereof of the
Company referred to in that certain Securities Purchase Agreement dated as of
the date hereof between the Company and the Purchaser named therein (the
"Agreement"). The Agreement and the Security Agreement contain certain
additional agreements among the parties with respect to the terms of this Note,
including, without limitation, definitions and provisions which (A) specify
voluntary and mandatory repayment, prepayment and redemption rights and
obligations and (B) specify Events of Default following which the remaining
balance due and owing hereunder may be accelerated. All such definitions and
provisions are an integral part of this Note and are incorporated herein by
reference. This Note is transferable and assignable to one or more Persons, in
accordance with the limitations set forth in the Agreement.

         The Company shall keep a register (the "Register") in which shall be
entered the names and addresses of the registered holder of this Note and
particulars of this Note held by such holder and of all transfers of this Note.
References to the Holder or "Holders" shall mean the Person listed in the
Register as registered holder of such Notes. The ownership of this Note shall be
proven by the Register.


1. CERTAIN TERMS DEFINED. All terms defined in the Agreement and not otherwise
defined herein shall have for purposes hereof the meanings provided for in the
Agreement.

2. COVENANTS. The Company covenants and agrees to observe and perform each of
its covenants, obligations and undertakings contained in the Agreement, which
obligations and undertakings are expressly assumed herein by the Company and
made for the benefit of the holder hereof.

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3. PAYMENT OF PRINCIPAL.

         3.1 PREPAYMENT OF NOTE. For so long as no Event of Default shall have
         occurred and is continuing and the Company is not in receipt of a
         Notice of Conversion from the Holder of the Note, the Company may, at
         its option, prepay, in whole or in part, this Convertible Note for a
         pre-payment price (the "Prepayment Price") equal to (i) 102% of the
         Principal Amount of the Note, plus all accrued but unpaid interest
         until the first anniversary of the date of this Convertible Note; and
         (ii) 101% of the Principal Amount of the Note, plus all accrued and
         unpaid interest on any day following the first anniversary of this
         Convertible Note. Any partial prepayment of the Convertible Note, at
         any time after issuance, shall be credited to the principal amount of
         the Convertible Note equal to such partial prepayment amount. The
         Company shall not be entitled to send any notice of prepayment and
         begin the prepayment procedure unless it has (i) the appropriate
         Prepayment Price, in cash, available in a demand or other immediately
         available account in a bank or similar financial institution or (ii)
         immediately available credit facilities, in the amount of the
         appropriate Prepayment Price, with a bank or similar financial
         institution on the date the prepayment notice is sent to the Holders of
         this Convertible Note. Provided, however, the Company will process any
         Notice of Conversion received prior to the issuance of a notice of
         prepayment; and further provided that, after a notice of prepayment has
         been issued, the Holder may issue a Notice of Conversion which will not
         be honored unless the Company fails to make the prepayment payment when
         due. In the event of such failure, the Notice of Conversion will be
         honored as of the date of the Notice of Conversion

         3.2 PAYMENT ON MATURITY DATE. The Company shall repay the remaining
         unpaid balance of this Convertible Note on the Maturity Date.

4. CONVERSION.

         4.1 CONVERSION OF CONVERTIBLE NOTE. Subject to Section 5 hereof, the
         Holder shall have the right, at its option, at any time from and after
         the date of this Convertible Note to convert into Common Stock of the
         Company. This Convertible Note shall be convertible into that number of
         fully paid and nonassessable shares of Common Stock (as such shares
         shall then be constituted) determined pursuant to this Section 4.1. The
         number of shares of Common Stock to be issued upon each conversion of
         this Convertible Note shall be determined by dividing the Conversion
         Amount (as defined below) by the Conversion Price in effect on the date
         (the "Conversion Date") a Notice of Conversion is delivered to the
         Company, as applicable, by the Holder by facsimile or other reasonable
         means of communication dispatched prior to 5:00 p.m., E.S.T. The term
         "Conversion Amount" means, with respect to any conversion of this
         Convertible Note, the sum of (1) the principal amount of this
         Convertible Note to be converted in such conversion plus (2) accrued
         and unpaid interest, if any, on such principal amount at the interest
         rates provided in this Convertible Note to the Conversion Date plus (3)
         Default Interest, if any, on the interest referred to in the
         immediately preceding clause (2) plus (4) at the Holder's option, any
         amounts owed to the Holder pursuant to Section 4.3 hereof, Section 10.1
         of the Agreement or Section 10.4 of the Agreement.


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         4.2 CONVERSION PRICE. At the option of the Holder, any portion or all
         of the outstanding principal amount of this Convertible Note shall be
         converted into a number of shares of Common Stock at the conversion
         price (the "Conversion Price") equal to the lesser of (i) the VWAP, as
         reported on Bloomberg, L.P. ("Bloomberg") on the Trading Day
         immediately prior to the Closing Date; or (ii) 85% of the average of
         the three lowest VWAPs, as reported by Bloomberg, during the ten (10)
         Trading Days immediately preceding the date of the related notice of
         conversion; provided further, however, that, for the six (6) month
         period following the Effective Date, in no event will the Conversion
         Price be lower than the lesser of (y) $1.50 or (z) 50% of the VWAP, as
         reported by Bloomberg, on the Effective Date of the Registration
         Statement. Upon expiration of the foregoing six (6) month period or
         upon occurrence of an Event of Default which is not cured, the
         foregoing floor calculation shall no longer be effective and shall
         disappear permanently.

         4.3 AUTHORIZED SHARES.

                  (a) Consistent with Section 7.11 of the Agreement, the Company
         (i) shall promptly irrevocably instruct the Company's transfer agent to
         issue certificates for the Common Stock issuable upon conversion of
         this Convertible Note and (ii) agrees that its issuance of this
         Convertible Note shall constitute full authority to its officers and
         agents who are charged with the duty of executing stock certificates to
         execute and issue the necessary certificates for shares of Common Stock
         in accordance with the terms and conditions of this Convertible Note.

                  (b) If at any time the Holder submits a Notice of Conversion
         and (x) the Company does not have sufficient authorized but unissued
         shares of Common stock available to effect such conversion in full in
         accordance with Article 4 or (y) the Company is prohibited by the OTC
         Bulletin Board or any National Market on which the Common Shares are
         listed and traded at that time to effect such conversion in full,
         without shareholder approval, the Company shall issue to the Holder all
         of the shares of Common Stock which are then available to effect such
         conversion. The portion of this Convertible Note which the Holder
         included in its Conversion Notice and which exceeds the amount which is
         then convertible into available shares of Common Stock (the "Excess
         Amount") shall, notwithstanding anything to the contrary contained
         herein, not be convertible into Common Stock until the date additional
         shares of Common Stock are authorized by the Company, or its
         shareholders, as applicable. The Company shall use its best efforts to
         authorize, or cause its shareholders to authorize within 40 days of the
         submission of the Conversion Notice, a sufficient number of shares of
         Common Stock to effect the full conversion set forth in the Conversion
         Notice.

                  (c) In no event shall the Company issue upon conversion of
         this Convertible Note more than the maximum number of shares allowable
         without shareholder approval under the applicable rules of the OTC
         Bulletin Board or any National Market on which the Common Shares are
         listed and traded unless the Company shall have obtained approval by


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         the shareholders of the Company or a waiver of such requirement. Once
         the maximum number of shares has been issued (the date of which is
         hereinafter referred to as the "Maximum Conversion Date"), unless the
         Company shall have obtained shareholder approval or a waiver of such
         requirement within 40 days of the Maximum Conversion Date, the Company
         shall pay to the Fund the Redemption Price.

                  (d) The Maximum Number of Shares shall be subject to
         adjustment from time to time for stock splits, stock dividends,
         combinations, capital reorganizations and similar events relating to
         the Common Stock occurring after the date hereof as contemplated by
         Article XI of the Agreement. In the event that the Company obtains
         Stockholder Approval, approval of the OTC Bulletin Board or the
         National Market on which the Common Shares are listed and traded at
         that time, or otherwise is able to increase the number of shares to be
         issued above the Maximum Number of Shares (such increased number being
         the "New Maximum Number of Shares"), the references to Maximum Number
         of Shares above shall be deemed to be, instead, references to the New
         Maximum Number of Shares.

         4.4 METHOD OF CONVERSION.

                  (a) Notwithstanding anything to the contrary set forth herein,
         upon conversion of this Convertible Note in accordance with the terms
         hereof, the Holder shall not be required to physically surrender this
         Convertible Note to the Company unless the entire unpaid principal
         amount of this Convertible Note is so converted. Rather, records
         showing the principal amount converted (or otherwise repaid) and the
         date of such conversion or repayment shall be maintained on a ledger
         substantially in the form of ANNEX A attached hereto (a copy of which
         shall be delivered to the Company or transfer agent with each Notice of
         Conversion). It is specifically contemplated that the Holder hereof
         shall act as the calculation agent for conversions and repayments. In
         the event of any dispute or discrepancies, such records maintained by
         the Holder shall be controlling and determinative in the absence of
         manifest error or failure of Holder to record the principal amount
         converted (or otherwise repaid) from time to time, in which events the
         record of the Company shall be controlling and determinative. The
         Holder and any assignee, by acceptance of this Convertible Note,
         acknowledge and agree that, by reason of the provisions of this
         paragraph, following a conversion of a portion of this Convertible
         Note, the principal amount represented by this Convertible Note will be
         the amount indicated on ANNEX A attached hereto (which may be less than
         the amount stated on the face hereof).

                  (b) The Company shall not be required to pay any tax which may
         be payable in respect of any transfer involved in the issuance and
         delivery of shares of Common Stock or other securities or property on
         conversion of this Convertible Note in a name other than that of the
         Holder (or in street name), and the Company shall not be required to
         issue or deliver any such shares or other securities or property unless
         and until the person or persons (other than the Holder or the custodian
         in whose street name such shares are to be held for the Holder's
         account) requesting the issuance thereof shall have paid to the Company
         the amount of any such tax or shall have established to the
         satisfaction of the Company that such tax has been paid.

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                  (c) Subject to Section 5 hereof, upon receipt by the Company
         of a Notice of Conversion, the Holder shall be deemed to be the holder
         of record of the Common Stock issuable upon such conversion, the
         outstanding principal amount and the amount of accrued and unpaid
         interest on this Convertible Note shall be deemed reduced to reflect
         such conversion, and, unless the Company defaults on its obligations
         under this Article 4, all rights with respect to the portion of this
         Convertible Note being so converted shall forthwith terminate except
         the right to receive the Common Stock or other securities, cash or
         other assets, as herein provided, on such conversion. Subject to
         Section 5 hereof, if the Holder shall have given a Notice of Conversion
         as provided herein, the Company's obligation to issue and deliver the
         certificates for shares of Common Stock shall be absolute and
         unconditional, irrespective of the absence of any action by the Holder
         to enforce the same, any waiver or consent with respect to any
         provisions thereof, the recovery of any judgment against any person or
         any action by the Holder to enforce the same, any failure or delay in
         the enforcement of any other obligation of the Company to the Holder of
         record, or any setoff, counterclaim, recoupment, limitation or
         termination, or any breach or alleged breach by the Holder of any
         obligation to the Company, and subject to Section 4.4(a) irrespective
         of any other circumstance which might otherwise limit such obligation
         of the Company to the Holder in connection with such conversion. The
         date of receipt (including receipt via telecopy) of such Notice of
         Conversion shall be the Conversion Date so long as it is received
         before 5:00 p.m., E.S.T., on such date.

                  (d) Notwithstanding the foregoing, if a Holder has not
         received certificates for all shares of Common Stock prior to the
         expiration of the Deadline with respect to a conversion of any portion
         of this Convertible Note for any reason, then (unless the Holder
         otherwise elects to retain its status as a holder of Common Stock by so
         notifying the Company), the Holder shall regain the rights of a Holder
         of this Convertible Note with respect to such unconverted portions of
         this Convertible Note and the Company shall, as soon as practicable,
         return such unconverted Convertible Note to the holder or, if the
         Convertible Note has not been surrendered, adjust its records to
         reflect that such portion of this Convertible Note not been converted.
         In all cases, the Holder shall retain all of its rights and remedies
         including, without limitation, the right to receive any amounts due
         pursuant to Section 10.1 of the Agreement.

                  (e) In lieu of delivering physical certificates representing
         the Common Stock issuable upon conversion, provided the Company's
         transfer agent is participating in the Depository Trust Company ("DTC")
         Fast Automated Securities Transfer program, upon request of the Holder
         and its compliance with the provisions contained in Section 4.1 and in
         this Section 4.4, the Company shall use its best efforts to cause its
         transfer agent to electronically transmit the Common Stock issuable
         upon conversion to the Holder by crediting the account of Holder's
         Prime Broker with DTC through its Deposit Withdrawal Agent Commission
         System.

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5. REDEMPTION BY COMPANY.

         5.1 MANDATORY REDEMPTION. In accordance with the provisions of the
         Purchase Agreement, the Company may be required under certain
         circumstances, to redeem in whole or in part, the remaining unpaid
         principal amount of this Convertible Note, for cash at a redemption
         price (the "Redemption Price") equal to the applicable Prepayment
         Price.

         5.2 MECHANICS OF REDEMPTION. The Company shall effect each such
         redemption within seven business days of receiving a notice to redeem
         by facsimile with a copy by either overnight or 2-day courier from the
         Holder of this Convertible Note. Such redemption notice shall indicate
         whether the Company is required to redeem all or part of such portion
         of the Convertible Note and the applicable Redemption Price.

         5.3 PAYMENT OF REDEMPTION PRICE. The Redemption Price shall be paid to
         the Holder of this Convertible Note within seven business days of the
         delivery of the notice of such redemption to such Holder.

6. MISCELLANEOUS. This Convertible Note shall be deemed to be a contract made
under the laws of the State of Texas, and for all purposes shall be governed by
and construed in accordance with the laws of said State. The parties hereto,
including all guarantors or endorsers, hereby waive presentment, demand, notice,
protest and all other demands and notices in connection with the delivery,
acceptance, performance and enforcement of this Convertible Note, except as
specifically provided herein, and asset to extensions of the time of payment, or
forbearance or other indulgence without notice. The Company hereby submits to
the exclusive jurisdiction of the United States District Court for the State of
Texas and any state court sitting in Texas for purposes of all legal proceedings
arising out of or relating to this Convertible Note. The Company irrevocably
waives, to the fullest extent permitted by law, any objection which it may now
or hereafter have to the laying of the venue of any such proceeding brought in
such a court and any claim that any such proceeding brought in such a court has
been brought in an inconvenient forum. The Company hereby irrevocably waives any
and all right to trial by jury in any legal proceeding arising out of or
relating to this Convertible Note.

         The Holder of this Convertible Note by acceptance of this Convertible
Note agrees to be bound by the provisions of this Convertible Note which are
expressly binding on such Holder.




                             SIGNATURE PAGE FOLLOWS


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         IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed.

         Dated: September 13, 2005



                                                     ERF WIRELESS, INC.


                                                     By: /s/ R. Greg Smith
                                                     Name: R. Greg Smith
                                                     Title: CEO/CFO






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                                    ANNEX A

                        CONVERSION AND REPAYMENT LEDGER
                        -------------------------------

                    Interest     Principal      New
       Principal    Converted    Converted   Principal   Issuer       Holder
Date    Balance     or Paid       or Paid     Balance    Initials    Initials
----    -------     -------       -------     -------    --------    --------

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



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FULL NAME AND ADDRESS OF SUBSCRIBER FOR REGISTRATION PURPOSES:

NAME:

ADDRESS:

TEL NO:

FAX NO;

CONTACT
NAME;


DELIVERY INSTRUCTIONS (IF DIFFERENT FROM REGISTRATION NAME);

NAME;

ADDRESS;

TEL NO:

FAX NO:

CONTACT
NAME;

SPECIAL INSTRUCTIONS:





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                              NOTICE OF CONVERSION

                    (To be Executed by the Registered Holder
                   In order to Convert the Convertible Note)


The undersigned hereby irrevocably elects to convert $________ of the principal
balance of the Convertible Note into shares of Common Stock, ___ par value per
share (the "Common Stock"), of ERF Wireless, Inc. (the "Company") according to
the conditions hereof, as of the date written below. No fee will be charged to
the Holder for any conversion, except for transfer taxes, if any. The
undersigned, as contemplated by Section 5.1 of the Securities Purchase Agreement
pursuant to which the Convertible Note was issued, hereby states that the
representations and warranties of the undersigned set forth therein are true and
correct in all material respects as of the date hereof (provided, the
undersigned makes no representation concerning its investment intent with
respect to the Common Stock received upon this conversion).


Conversion calculations:


---------------------------------------------
Date pf Conversion


---------------------------------------------
Applicable Conversion Price


---------------------------------------------
Number of Shares


---------------------------------------------
Name/Signature


Address:

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

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