<PAGE>
                                                                   Exhibit 4.4.4

                              FOURTH AMENDMENT

     THIS FOURTH AMENDMENT (this "AMENDMENT") is entered into as of July 28,
2000, between SYGNET WIRELESS, INC. (successor by merger to Dobson/Sygnet
Operating Company), an Ohio corporation ("BORROWER"), the Required Lenders under
the Credit Agreement (hereinafter defined), BANK OF AMERICA, N.A. (successor to
NationsBank, N.A.), in its capacity as Administrative Agent for the Lenders
under the Credit Agreement ("ADMINISTRATIVE AGENT"), and Guarantors under the
Credit Agreement. Reference is made to that certain Credit Agreement, dated as
of December 23, 1998 (as amended, modified, supplemented, or restated from time
to time, the "CREDIT AGREEMENT"), among Borrower, Administrative Agent, Lehman
Commercial Paper Inc. and PNC Bank, National Association, as Co-Syndication
Agents, Toronto Dominion (Texas), Inc. and First Union National Bank, as
Co-Documentation Agents, and the Lenders party thereto.

     Unless otherwise defined in this Amendment, capitalized terms used herein
shall have the meaning set forth in the Credit Agreement. Unless otherwise
indicated, all Paragraph references herein are to Paragraphs in this Amendment,
and all Section references herein are to Sections in the Credit Agreement.

                                    RECITALS

     A. Borrower has requested that Required Lenders agree to make certain
amendments to the Credit Agreement, including without limitation, changes to
certain financial covenants.

     B. Required Lenders are willing to amend the Credit Agreement to make the
requested changes, but only upon the conditions, among other things, that
Borrower, each Guarantor under the Credit Agreement, and Required Lenders shall
have executed and delivered this Amendment and shall have agreed to the terms
and conditions of this Amendment.

     NOW, THEREFORE, in consideration of these premises and other valuable
consideration, the receipt and adequacy of which are hereby acknowledged, the
parties hereto agree, as follows:

PARAGRAPH 1. AMENDMENTS.

     1.1 DEFINITIONS.

     (a) The definition of "Applicable Margin" is amended by deleting CLAUSE
(i) in the paragraph following CLAUSE (c) thereof in its entirety and
substituting the following therefor:

         "(i) Until the second Business Day after the initial Financial
Statements and Compliance Certificate for the fiscal quarter ending December
31, 1998, shall have been delivered hereunder, the Applicable Margin for Base
Rate Borrowings and Eurodollar Rate Borrowings under the Revolver Facility,
Term Loan A, and Term Loan B shall be determined by reference to a Compliance
Certificate delivered by Borrower on the Closing Date. From July 1, 2000, until
the second Business Day after the Financial Statements and Compliance
Certificate for the fiscal quarter ending December 31, 2000, shall have been
delivered hereunder, the Applicable Margin for Base Rate Borrowings and
Eurodollar Rate Borrowings under the Revolver Facility, Term Loan A, and Term
Loan B shall be the highest Applicable Margin for the relevant Type of
Borrowing for the relevant Facility. With respect to any adjustments in the
Applicable Margin as a result of changes in the Leverage Ratio, such adjustment
shall be effective

                                                                FOURTH AMENDMENT
<PAGE>
          commencing on the second Business Day after the delivery of Financial
          Statements (and the related Compliance Certificate) pursuant to
          SECTIONS 9.3(a) and 9.3(b) or the most recent Permitted Acquisition
          Compliance Certificate for a Permitted Acquisition, as the case may
          be; and"

     (b)  the definition of "Interest Expense" is amended by (i) deleting the
words "and payable in cash during such period" from the first sentence thereof
and (ii) deleting the second and third sentences thereof in the entirety and
substituting therefor the following sentences:

          "With respect to the calculation of Interest Expense for Borrower and
          the Companies, unless otherwise specified, Interest Expense shall
          include (without duplication) the aggregate amount of interest on the
          Senior Reserve Notes (whether accrued or actually paid in cash). With
          respect to the calculation of Interest Expense for Borrower and the
          Companies or Parent, Interest Expense shall expressly exclude any
          interest paid on the Senior Reserve Notes from the proceeds of the
          Pledged Government Securities securing such Senior Reserve Notes."

     (c)  The definition of "Pro Forma Interest Expense" is amended by deleting
the lead-in paragraph in its entirety and substituting therefor the following
paragraph:

          "PRO FORMA INTEREST EXPENSE means, at any date of determination with
          respect to the most recently ended Rolling Period (the "SUBJECT
          PERIOD"), calculated for the Companies on a consolidated basis, the
          sum of (i) on and after January 1, 2002, the aggregate amount of
          interest on the Senior Reserve Notes (whether accrued or actually paid
          in cash), plus (ii) the sum of the results of the following
          calculation made separately with respect to each Borrowing and each
          other loan or other evidence of Debt of any Company (each a "SUBJECT
          LOAN" for the purposes hereof):"


     (d)  The following definitions of "Fourth Amendment," "Fourth Amendment
Date," "July Equity Issuance," "July Equity Proceeds," and "Maximum Equity"
shall be alphabetically inserted in SECTION 1.1 to read, as follows:

          "FOURTH AMENDMENT means that certain Fourth Amendment dated as of
          July 28, 2000, among Borrower, Guarantors, and Required Lenders."

          "FOURTH AMENDMENT DATE means the date upon which the Fourth Amendment
          becomes effective in accordance with the terms of such Fourth
          Amendment."

          "JULY EQUITY ISSUANCE means the Equity Issuance of common stock by
          Borrower to Parent which shall occur on a date not later than the
          Fourth Amendment Date yielding Net Cash Proceeds to Borrower of not
          less than $25,000,000."

          "JULY EQUITY PROCEEDS means the Net Cash Proceeds from the July Equity
          Issuance received by Borrower and used to prepay the Obligation in
          accordance with SECTION 2.7(b)(iii)."

          "MAXIMUM EQUITY means:

                                       2
                                                                FOURTH AMENDMENT





<PAGE>
          (a) with respect to the calculation of the Pro Forma Debt
          Service Coverage Ratio set forth in SECTION 9.30(b), the
          amount set forth below which corresponds to the applicable
          fiscal quarter:



          QUARTER ENDING                              MAXIMUM EQUITY
-------------------------------------    --------------------------------------
          September 30, 2001                            $2,000,000

          December 31, 2001                             $6,000,000

            March 31, 2002                              $7,000,000

            June 30, 2002                               $8,000,000

         September 30, 2002                             $6,500,000

      December 31, 2002, March                          $7,000,000
      31, 2003, June 30, 2003,
      September 30, 2003 and
        December 31, 2003

      March 31, 2004, June 30,                         $20,000,000
      2004, September 30, 2004,
       and December 31, 2004

          and

          (b)  with respect to the calculation of the Fixed Charge
          Coverage Ratio set forth in SECTION 9.30(d), the amount set
          forth below which corresponds to the applicable fiscal
          quarter:



          QUARTER ENDING                              MAXIMUM EQUITY
-------------------------------------    --------------------------------------
          September 30, 2002                            $2,000,000

          December 31, 2002                             $5,000,000

     March 31, 2003, June 30,                          $14,000,000
     2003, September 30, 2003,
      and December 31, 2003

     March 31, 2004, June 30,                           $4,000,000
     2004, September 30, 2004,
      and December 31, 2004


     March 31, 2005, June 30,                          $17,500,000
     2005, September 30, 2005,
      and December 31, 2005

     1.2 OPTIONAL PREPAYMENTS.

     (a)  CLAUSE (ii) in the proviso of SECTION 2.7(a)(i) is amended by
deleting such clause in its entirety and substituting the following therefor:

          "(ii) each such partial prepayment must be in a minimum
          amount of at least $3,000,000 (other than prepayment of
          Swing Line Borrowings which may be in integral multiples of
          $250,000 and prepayments made concurrently with mandatory
          prepayments made pursuant to SECTION 2.7(b) and (c)) or a
          greater integral multiple of $2,000,000 thereof;"



                                       3

                                                                FOURTH AMENDMENT
<PAGE>
     (b)  CLAUSE (ii) in the proviso of SECTION 2.7(a)(ii) is amended by
deleting such clause in its entirety and substituting the following therefor:

          "(ii) each such partial prepayment must be in a minimum
          amount of at least $5,000,000 (other than prepayments made
          concurrently with mandatory prepayments made pursuant to
          SECTION 2.7(b) and (c)) or a greater integral multiple of
          $1,000,000 thereof;"

     1.3  FINANCIAL COVENANTS.

     (a)  The Leverage Ratio covenant set forth in SECTION 9.30(a) is amended
by substituting the following table for the table set forth at the end of such
Section:

                PERIOD                                     RATIO
-------------------------------------      ------------------------------------
On and after the Closing Date to and                    7.60 to 1
     including June 30, 1999

On and after July 1, 1999, to and                       7.25 to 1
     including December 31, 1999

On and after January 1, 2000, to and                    6.75 to 1
     including June 29, 2000

On and after June 30, 2000, to and                      6.50 to 1
     including December 30, 2000

On and after December 31, 2000, to                      6.10 to 1
   and including March 30, 2001

On and after March 31, 2001, to and                     5.60 to 1
    including June 29, 2001

On and after June 30, 2001, to and                      5.35 to 1
    including September 29, 2001

On and after September 30, 2001, to                     5.00 to 1
  and including December 30, 2001

On and after December 31, 2001, to                      4.75 to 1
  and including March 30, 2002

On and after March 31, 2002, to and                     4.50 to 1
   including September 29, 2002

On and after September 30, 2002, to                     4.00 to 1
     and including June 29, 2003

     On and after June 30, 2003                         3.50 to 1



(b)  SECTION 9.30(b) is deleted in its entirety and the following provision is
     substituted therefor:

          "(b) Pro Forma Debt Service Coverage. Borrower shall never
          permit the ratio of the Operating Cash Flow for the
          Companies to the Pro Forma Debt Service as of the last day
          of any fiscal quarter to be less than or equal




                                       4
                                                                FOURTH AMENDMENT
<PAGE>
          to the ratio shown in the table below which corresponds to
          the applicable fiscal quarter:



          FISCAL QUARTER(S)                      PRO FORMA DEBT SERVICE
              ENDING                                 COVERAGE RATIO
-------------------------------------    --------------------------------------
      December 31, 1998, March                         1.10 to 1
      31, 1999, June 30, 1999,
        September 30, 1999,
      December 31, 1999, and
          March 31, 2000

          June 30, 2000                                1.25 to 1

       September 30, 2000                              1.15 to 1

       December 31, 2000                               1.30 to 1

        March 31, 2001                                 1.20 to 1

  June 30, 2001, and thereafter                        1.05 to 1

          ; provided that, solely for purposes of calculating the
          numerator of the Pro Forma Debt Service Coverage Ratio, the
          Operating Cash Flow for the Companies may be increased by an
          amount equal to (i) 100% of the July Equity Proceeds for the
          fiscal quarter ending June 30, 2000, (ii) 75% of the July
          Equity Proceeds for the fiscal quarter ending September 30,
          2000, (iii) 50% of the July Equity Proceeds for the fiscal
          quarter ending December 31, 2000; (iv) 25% of the July
          Equity Proceeds for the fiscal quarter ending March 31,
          2001, and (v) in any fiscal quarter occurring from July 1,
          2001, through and including December 31, 2004, in which any
          Equity Issuance is consummated (each an "EQUITY ISSUANCE
          QUARTER"), 100% of the aggregate Net Cash Proceeds of any
          Equity Issuance during such Equity Issuance Quarter, so long
          as such Net Cash Proceeds were used to prepay the
          Obligation pursuant to SECTION 2.7(b)(iii); provided further
          that (x) the adjustments in CLAUSE (v) may be continued in
          each of the three fiscal quarters immediately following any
          Equity Issuance Quarter (each a "CARRY-FORWARD QUARTER"),
          but the amount of such Equity Issuance Net Cash Proceeds
          adjustment shall be reduced by 25% in the first Carry-Forward
          Quarter, 50% in the second Carry-Forward Quarter, and 75% in
          the third Carry-Forward Quarter, and (y) notwithstanding
          anything herein to the contrary, in any fiscal quarter the
          aggregate increase in Operating Cash Flow made pursuant to
          CLAUSES (v) AND (x) preceding shall not exceed the Maximum
          Equity for such fiscal quarter."

(c)       SECTION 9.30(c) is deleted in its entirety and the following provision
          is substituted therefor:

          "(c) Interest Coverage.  Borrower shall never permit the
          ratio (determined, on March 31, 1999, for the fiscal quarter
          period then-ending; on June 30, 1999, for the two-fiscal
          quarter period then-ending; on September 30, 1999, for the
          three-fiscal quarter period then-ending; and thereafter, on
          a quarterly basis for the Rolling Period then-ending) of (i)
          its Operating Cash Flow to (ii) its Interest Expense, to be
          less than the ratio

                                       5
                                                                FOURTH AMENDMENT
<PAGE>
          shown in the table below which corresponds to the applicable
          period of determination:

                                                       INTEREST
                PERIOD                              COVERAGE RATIO
-------------------------------------    --------------------------------------
    On and after January 1, 1999,                      1.25 to 1
   to and including December 31,
               1999

   On and after January 1, 2000,                       1.50 to 1
  to and including June 29, 2000

   On and after June 30, 2000, to                      1.35 to 1
     and including September 29,
               2000

    On and after September 30,                         1.45 to 1
     2000, to and including
       December 30, 2000

   On and after December 31,                           1.50 to 1
  2000, to and including March
            30, 2001

   On and after March 31, 2001,                        1.75 to 1
  to and including June 29, 2002

  On and after June 30, 2002, to                       1.60 to 1
   and including September 29,
             2002

    On and after September 30,                         1.50 to 1
     2002, to and including
       December 30, 2002

   On and after December 31,                           1.40 to 1
   2002, to and including June
          29, 2003

  On and after June 30, 2003, to                       1.60 to 1
    and including September 29,
              2003

   On and after September 20,                          1.75 to 1
             2003



(d)       SECTION 9.30(D) is deleted in its entirety and the following provision
          is substituted therefor:

          "(d) Fixed Charge Coverage Ratio.  For the periods on and
          after the Closing Date through March 31, 2000, and on and
          after December 31, 2001, Borrower shall never permit its
          Fixed Charge Coverage Ratio as of the last day of any fiscal
          quarter to be less than or equal to 1.00 to 1.0; provided
          that, solely for purposes of calculating the numerator of
          the Fixed



                                       6

                                                                FOURTH AMENDMENT
<PAGE>
          Charge Coverage Ratio, in any fiscal quarter occurring from
          July 1, 2002, through and including December 31, 2005, in
          which any Equity Issuance is consummated (each an "EQUITY
          ISSUANCE QUARTER"), the Operating Cash Flow for the
          Companies may be increased by an amount equal to, 100% of
          the aggregate Net Cash Proceeds of any Equity Issuance
          during such Equity Issuance Quarter, so long as such Net
          Cash Proceeds were used to prepay the Obligation pursuant to
          SECTION 2.7(B)(III); provided further that (x) the
          adjustments herein may be continued in each of the three
          fiscal quarters immediately following any Equity Issuance
          Quarter (each a "CARRY-FORWARD QUARTER"), but the amount of
          such Equity Issuance Net Cash Proceeds adjustment shall be
          reduced by 25% in the first Carry-Forward Quarter, 50% in
          the second Carry-Forward Quarter, and 75% in the third
          Carry-Forward Quarter, and (y) notwithstanding anything
          herein to the contrary, in any fiscal quarter the aggregate
          increase in Operating Cash Flow made pursuant hereto shall
          not exceed the Maximum Equity for such fiscal quarter."

     (e)  The Consolidated Leverage Ratio covenant set forth in SECTION 9.30(E)
is amended by substituting the following table for the table set forth at the
end of such Section:


                PERIOD                                     RATIO
-------------------------------------      -----------------------------------
 On and after the March 31, 2002, to                   7.25 to 1
    and including June 29, 2002

 On and after June 30, 2002, to and                    7.00 to 1
    including September 29, 2002

 On and after September 30, 2002, to                   6.60 to 1
  and including December 30, 2002

 On and December 31, 2002, to and                      6.35 to 1
    including March 30, 2003

On and after March 31, 2003, to and                    6.00 to 1
    including June 29, 2003

 On and after June 30, 2003, to and                    5.50 to 1
  including December 30, 2003

 On and after December 31, 2003, to                    5.00 to 1
  and including September 29, 2004

 On and after September 30, 2004, to                   4.75 to 1
  and including December 30, 2004

  On and after December 31, 2004                       4.25 to 1

(f)       A new SECTION 9.30(G) is added as follows:

          "(g) Capital Expenditures.    Borrower shall not permit the
          aggregate amount of Capital Expenditures during the calendar
          year 2000 to exceed $40,000,000."



                                       7
                                                                FOURTH AMENDMENT
<PAGE>
     1.4 EXHIBIT E-1. Annex B to the Form of Certificate set forth on Exhibit
E-1 to the Credit Agreement, is deleted in its entirety and the document labeled
Revised Annex B to Compliance Certificate attached hereto shall be substituted
therefor.

PARAGRAPH 2. AMENDMENT FEES. On the Effective Date, Borrower shall pay (a) to
Administrative Agent (for the ratable benefit of the Revolver Lenders consenting
to this Amendment on or prior to the Effective Date, the "CONSENTING REVOLVER
LENDERS"), an amendment fee in an amount equal to 0.25% of the aggregate
Committed Sums under the Revolver Facility of each Consenting Revolver Lender as
of the Effective Date but prior to the prepayment from the Net Cash Proceeds of
the July Equity Issuance and (b) to Administrative Agent (for the ratable
benefit of the Term Loan A Lenders, the Term Loan B Lenders, and the Term Loan C
Lenders consenting to this Amendment on or prior to the Effective Date, the
"CONSENTING TERM LOAN LENDERS"), an amendment fee in an amount equal to 0.25% of
the aggregate Term Loan A Principal Debt, Term Loan B Principal Debt, or Term
Loan C Principal Debt owed to the Consenting Term Loan Lenders as of the
Effective Date but prior to the prepayment from the Net Cash Proceeds of the
July Equity Issuance. The failure of Borrower to comply with the provisions of
this PARAGRAPH 2 shall constitute a payment Default entitling Lenders to
exercise their respective Rights under the Loan Papers.

PARAGRAPH 3. CONDITIONS. Notwithstanding any contrary provision, this Amendment
is not effective until the date upon which (a) the representations and
warranties in this Amendment are true and correct; (b) Administrative Agent
receives counterparts of this Amendment executed by Borrower, each Guarantor,
and Required Lenders; (c) payment of the amendment fees required to be paid to
consenting Lenders and Administrative Agent on the Effective Date pursuant to
PARAGRAPH 2 hereof; and (d) evidence satisfactory to Administrative Agent that
July Equity Proceeds of not less than $25,000,000 have been received by Borrower
and the mandatory prepayments required by SECTION 2.7(B)(III) have been made. On
the Business Day upon which all of the preceding conditions precedent are
satisfied, this Amendment shall be affective (the "EFFECTIVE DATE").

PARAGRAPH 4. ACKNOWLEDGMENT AND RATIFICATION. As a material inducement to
Administrative Agent and the Lenders to execute and deliver this Amendment,
Borrower and each Guarantor (i) consent to the agreements in this Amendment and
(ii) agree and acknowledge that the execution, delivery, and performance of this
Amendment shall in no way release, diminish, impair, reduce, or otherwise affect
the respective obligations of Borrower or Guarantors under their respective
Collateral Documents, which Collateral Documents shall remain in full force and
effect, and all Liens, guaranties, and Rights thereunder are hereby ratified and
confirmed.

PARAGRAPH 5. REPRESENTATIONS. As a material inducement to Administrative Agent
and Lenders to execute and deliver this Amendment, Borrower and each Guarantor
represent and warrant to such parties (with the knowledge and intent that the
Lenders and Administrative Agent are relying upon the same in entering into this
Amendment) that as of the Effective Date of this Amendment and as of the date of
execution of this Amendment: (a) all representations and warranties in the Loan
Papers are true and correct in all material respects as though made on the date
hereof, except to the extent that (i) any of them speak to a different specific
date or (ii) the facts on which any of them were based have been changed by
transactions permitted by the Loan Papers; (b) no Default or Potential Default
exists; and (c) this Amendment has been duly authorized and approved by all
necessary corporate action and requires the consent of no other Person, and upon
execution and delivery, this Amendment shall be binding and enforceable against
Borrower and each Guarantor in accordance with its terms.

PARAGRAPH 6. EXPENSES. Borrower shall pay all costs, fees, and expenses paid or
incurred by Administrative Agent incident to this Amendment, including, without
limitation, the reasonable fees and expenses of Administrative Agent's counsel
in connection with the negotiation, preparation, delivery, and execution of this
Amendment and any related documents.


                                       8
                                                                FOURTH AMENDMENT
<PAGE>
PARAGRAPH 7. MISCELLANEOUS.

     7.1 This Amendment is a "Loan Paper" referred to in the Credit Agreement,
and the provisions of SECTION 13 of the Credit Agreement are incorporated herein
by reference. Unless stated otherwise (a) the singular number includes the
plural and vice versa and words of any gender include each other gender, in each
case, as appropriate, (b) headings and captions may not be construed in
interpreting provisions, (c) this Amendment must be construed, and its
performance enforced, under Texas law, and (d) this Amendment may be executed in
any number of counterparts with the same effect as if all signatories had signed
the same document, and all of those counterparts must be construed together to
constitute the same document.

     7.2 The Loan Papers shall remain unchanged and in full force and effect,
except as provided in this Amendment, and are hereby ratified and confirmed. On
and after the Effective Date, all references to the "Credit Agreement" shall be
to the Credit Agreement as herein amended. The execution, delivery, and
effectiveness of this Amendment shall not, except as expressly provided herein,
operate as a waiver of any Rights of Lenders under any Loan Paper, nor
constitute a waiver under any of the Loan Papers.

PARAGRAPH 8. ENTIRETIES. THIS AMENDMENT REPRESENTS THE FINAL AGREEMENT BETWEEN
THE PARTIES ABOUT THE SUBJECT MATTER OF THIS AMENDMENT AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL
AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE
PARTIES.

PARAGRAPH 9. PARTIES. This Amendment binds and inures to Borrower,
Administrative Agent, Lenders, Guarantors, and their respective successors and
assigns.

     The parties hereto have executed this Amendment in multiple counterparts
on the date stated on the signature pages hereto, but effective as of Effective
Date.

                 [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK.]

                                       9
                                                                FOURTH AMENDMENT
<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                        SYGNET WIRELESS, INC. (successor by
                                        merger to Dobson/Sygnet Operating
                                        Company), as Borrower



                                        By: /s/ Richard D. Sewell, Jr.
                                            ------------------------------------
                                            Name: Richard D. Sewell, Jr.
                                            Title: Treasurer




                                        SYGNET COMMUNICATIONS, INC.,
                                        as Guarantor




                                        By: /s/ Richard D. Sewell, Jr.
                                            ------------------------------------
                                            Name: Richard D. Sewell, Jr.
                                            Title: Treasurer



                       Signature Page to Fourth Amendment

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                        BANK OF AMERICA, N.A. (successor to
                                        NationsBank, N.A., as Administrative
                                        Agent and a Lender



                                        By: /s/ Julie A. Schell
                                            ------------------------------------
                                            Name: Julie A. Schell
                                            Title: Principal




                       Signature Page to Fourth Amendment

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                 SYGNET WIRELESS, INC. (successor by merger to
                                 Dobson/Sygnet Operating Company), as Borrower

                                 By: /s/ RICHARD D. SEWELL JR.
                                    ------------------------------------------
                                    Name: Richard D. Sewell, Jr.
                                         -------------------------------------
                                    Title: Treasurer
                                          ------------------------------------


                                 SYGNET COMMUNICATIONS, INC., as Guarantor


                                 By: /s/ RICHARD D. SEWELL JR.
                                    ------------------------------------------
                                    Name: Richard D. Sewell, Jr.
                                         -------------------------------------
                                    Title: Treasurer
                                          ------------------------------------
<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.

                                 BANK OF AMERICA, N.A. (successor to
                                 NationsBank, N.A., as Administrative Agent
                                 and a Lender

                                 By: /s/ JULIE A. SCHELL
                                    ------------------------------------------
                                    Name: Julie A. Schell
                                         -------------------------------------
                                    Title: Principal
                                          ------------------------------------

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   FIRST UNION NATIONAL BANK,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ Harry E. Ellis
                                       ----------------------------------------
                                       Name:  HARRY E. ELLIS
                                             ----------------------------------
                                       Title: MANAGING DIRECTOR
                                              SENIOR VICE PRESIDENT
                                             ----------------------------------



                       SIGNATURE PAGE TO FOURTH AMENDMENT
<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   PNC BANK, NATIONAL ASSOCIATION,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ K. Kooman
                                       ----------------------------------------
                                       Name:  Karen L. Kooman
                                             ----------------------------------
                                       Title: Assistant Vice President
                                             ----------------------------------

                       SIGNATURE PAGE TO FOURTH AMENDMENT
<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   National City Bank,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ Theodore M. Schmidt
                                       ----------------------------------------
                                       Name:  THEODORE M. SCHMIDT
                                             ----------------------------------
                                       Title: VICE PRESIDENT
                                             ----------------------------------

                       SIGNATURE PAGE TO FOURTH AMENDMENT
<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   TORONTO DOMINION (TEXAS), INC.,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ Ann S. Slanis
                                       ----------------------------------------
                                       Name:  Ann S. Slanis
                                             ----------------------------------
                                       Title: Vice President
                                             ----------------------------------


                       SIGNATURE PAGE TO FOURTH AMENDMENT
<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   EATON VANCE SENIOR INCOME TRUST
                                   BY: EATON VANCE MANAGEMENT
                                   AS INVESTMENT ADVISOR,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ SCOTT H. PAGE
                                       ----------------------------------------
                                       Name:  SCOTT H. PAGE
                                             ----------------------------------
                                       Title: Vice President
                                             ----------------------------------


                       SIGNATURE PAGE TO FOURTH AMENDMENT
<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   SENIOR DEBT PORTFOLIO
                                   BY: BOSTON MANAGEMENT AND RESEARCH
                                   AS INVESTMENT ADVISOR,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ SCOTT H. PAGE
                                       ----------------------------------------
                                       Name:  SCOTT H. PAGE
                                             ----------------------------------
                                       Title: VICE PRESIDENT
                                             ----------------------------------

                       SIGNATURE PAGE TO FOURTH AMENDMENT
<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   The Bank of Nova Scotia,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ Paul A. Weissenberger
                                       ----------------------------------------
                                       Name:  P.A. WEISSENBERGER
                                             ----------------------------------
                                       Title: AUTHORIZED SIGNATORY
                                             ----------------------------------


                       Signature Page to Fourth Amendment

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   Bank of Montreal,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ Karen Klapper
                                       ----------------------------------------
                                       Name:  KAREN KLAPPER
                                             ----------------------------------
                                       Title: DIRECTOR
                                             ----------------------------------


                       Signature Page to Fourth Amendment

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   Union Bank of California, N.A.,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ Keith M. Wilson
                                       ----------------------------------------
                                       Name:  Keith M. Wilson
                                             ----------------------------------
                                       Title: Vice President
                                             ----------------------------------


                       Signature Page to Fourth Amendment

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.




                                   As Lender:




                                   NORTH AMERICAN SENIOR FLOATING RATE FUND

                                   By: CypressTree Investment Management
                                       Company, Inc. as Portfolio Manager


                                   By: /s/ Jonathan D. Sharkey
                                       ----------------------------------------
                                       Name:  Jonathan D. Sharkey
                                       Title: Principal





                                   CYPRESS TREE SENIOR FLOATING RATE FUND

                                   By: CypressTree Investment Management
                                       Company, Inc. as Portfolio Manager


                                   By: /s/ Jonathan D. Sharkey
                                       ----------------------------------------
                                       Name:  Jonathan D. Sharkey
                                       Title: Principal


                       Signature Page to Fourth Amendment

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   MERRILL LYNCH PRIME RATE PORTFOLIO
                                   By: Merrill Lynch Investment Managers, L.P.
                                       as Investment Advisor



                                   By: /s/ Andrew C. Liggio
                                       ----------------------------------------
                                       Name:  ANDREW C. LIGGIO
                                       Title: AUTHORIZED SIGNATORY



                       Signature Page to Fourth Amendment

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   Metropolitan Life Insurance Company
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ James R. Dingler
                                       ----------------------------------------
                                       Name:  James R. Dingler
                                             ----------------------------------
                                       Title: Director
                                             ----------------------------------


                       Signature Page to Fourth Amendment
<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   Credit Lyonnais New York Branch,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ Mark Campellone
                                       ----------------------------------------
                                       Name:  Mark Campellone
                                             ----------------------------------
                                       Title: First Vice President
                                             ----------------------------------


                       Signature Page to Fourth Amendment
<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   MERRILL LYNCH SENIOR FLOATING RATE FUND, INC.





                                   By: /s/ Andrew C. Liggio
                                       ----------------------------------------
                                                  ANDREW C. LIGGIO
                                                AUTHORIZED SIGNATORY


                       Signature Page to Fourth Amendment




<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   MERRILL LYNCH GLOBAL INVESTMENT SERIES:
                                   INCOME STRATEGIES PORTFOLIO
                                   By: Merrill Lynch Investment Managers, L.P.
                                       as Investment Advisor





                                   By: /s/ Andrew C. Liggio
                                       ----------------------------------------
                                                 ANDREW C. LIGGIO
                                               AUTHORIZED SIGNATORY


                       Signature Page to Fourth Amendment

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   U.S. Bank National Association,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ Andrew McDonald
                                       ----------------------------------------
                                       Name:  Andrew McDonald
                                             ----------------------------------
                                       Title: Senior Vice President
                                             ----------------------------------


                       Signature Page to Fourth Amendment

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   The CIT Group, Equipment Financing, Inc.,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ Daniel E. A. Nichols
                                       ----------------------------------------
                                       Name:  DANIEL E. A. NICHOLS
                                             ----------------------------------
                                       Title: ASSISTANT VICE PRESIDENT
                                             ----------------------------------


                       Signature Page to Fourth Amendment

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   OXFORD STRATEGIC INCOME FUND
                                   BY: EASTON VANCE MANAGEMENT
                                   AS INVESTMENT ADVISOR,
                                   --------------------------------------------
                                   as a Lender



                                   By: /s/ Scott H. Page
                                       ----------------------------------------
                                       Name:  SCOTT H. PAGE
                                             ----------------------------------
                                       Title: VICE PRESIDENT
                                             ----------------------------------


                       Signature Page to Fourth Amendment

<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   CIBC INC.,
                                   ---------------------------------------------
                                   as a Lender



                                   By: Laura Hom
                                       -----------------------------------------

                                       Name:  /s/ Laura Hom
                                              ----------------------------------

                                       Title: Executive Director
                                              CIBC World Markets Corp. As Agent
                                              ----------------------------------







                       Signature Page to Fourth Amendment
<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   The Fuji Bank, Limited,
                                   ---------------------------------------------
                                   as a Lender



                                   By: Masahito Fukuda
                                       -----------------------------------------

                                       Name:  /s/ Masahito Fukuda
                                              ----------------------------------

                                       Title: Senior Vice President
                                              ----------------------------------






                       Signature Page to Fourth Amendment
<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   Fremont Investment & Loan,
                                   ---------------------------------------------
                                   as a Lender



                                   By: /s/ Kannika Viravan
                                       -----------------------------------------

                                       Name:  Kannika Viravan
                                              ----------------------------------

                                       Title: Vice President
                                              ----------------------------------







                       Signature Page to Fourth Amendment
<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   VAN KAMPEN
                                   SENIOR INCOME TRUST
                                   By: Van Kampen Investment Advisory Corp.,
                                   ---------------------------------------------
                                   as a Lender



                                   By: /s/ Darvin D. Pierce
                                       -----------------------------------------

                                       Name:  DARVIN D. PIERCE
                                              ----------------------------------

                                       Title: VICE PRESIDENT
                                              ----------------------------------






                       Signature Page to Fourth Amendment
<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   VAN KAMPEN
                                   PRIME RATE INCOME TRUST
                                   By: Van Kampen Investment Advisory Corp.,
                                   ---------------------------------------------
                                   as a Lender



                                   By: /s/ Darvin D. Pierce
                                       -----------------------------------------

                                       Name:  DARVIN D. PIERCE
                                              ----------------------------------

                                       Title: Vice President
                                              ----------------------------------


                                   By: -----------------------------------------

                                       Name:
                                              ----------------------------------

                                       Title:
                                              ----------------------------------








                       Signature Page to Fourth Amendment
<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   SYNDICATED LOAN FUNDING TRUST,
                                   ---------------------------------------------
                                   as a Lender



                                   By: /s/ G. Andrew Keith
                                       -----------------------------------------

                                       Name:  G. Andrew Keith
                                              ----------------------------------

                                       Title: Authorized Signatory
                                              ----------------------------------






                       Signature Page to Fourth Amendment
<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   Stein Roe Floating Rate Limited Liability
                                   Company
                                   ---------------------------------------------
                                   as a Lender



                                   By: /s/ Brian W. Good
                                       -----------------------------------------

                                       Name:  Brian W. Good
                                              ----------------------------------

                                       Title: Senior Vice President
                                              ----------------------------------
                                              Stein Roe & Farnham Incorporated,
                                              as Advisor to the Stein Roe
                                              Floating Rate Limited Liability
                                              Company



                       Signature Page to Fourth Amendment

<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   Oak Mountain Ltd.,
                                   ---------------------------------------------
                                   as a Lender



                                   By: Alliance Capital,
                                       -----------------------------------------

                                       its Investment Advisor
                                           -------------------------------------



                                         By:  /s/ Robert Bayer
                                              ----------------------------------

                                              Name: Robert Bayer
                                              ----------------------------------
                                              Title: Vice President
                                              ----------------------------------



                       Signature Page to Fourth Amendment

<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                               MERRILL LYNCH SENIOR FLOATING RATE FUND II, INC.


                                        /s/ Andrew C. Liggio
                                        ----------------------------------------
                                        ANDREW C. LIGGIO
                                        AUTHORIZED SIGNATORY

                       Signature Page to Fourth Amendment

<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   Monument Capital Ltd.,
                                   ---------------------------------------------
                                   as a Lender



                                   By: Alliance Capital,
                                       -----------------------------------------

                                       its Investment Advisor
                                           -------------------------------------



                                         By:  /s/ Robert Bayer
                                              ----------------------------------

                                              Name: Robert Bayer
                                              ----------------------------------
                                              Title: Vice President
                                              ----------------------------------



                       Signature Page to Fourth Amendment

<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   ELC (Cayman) Ltd. CDO Series 1999-1,
                                   ---------------------------------------------
                                   as a Lender



                                   By: /s/ Adrienne Musgnug
                                       -----------------------------------------
                                       Name:  Adrienne Musgnug
                                              ----------------------------------
                                       Title: Director
                                              ----------------------------------


                       Signature Page to Fourth Amendment

<PAGE>

Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                                   ELC (Cayman) Ltd. 1999-II,
                                   ---------------------------------------------
                                   as a Lender



                                   By: /s/ Adrienne Musgnug
                                       -----------------------------------------
                                       Name:  Adrienne Musgnug
                                              ----------------------------------
                                       Title: Director
                                              ----------------------------------


                       Signature Page to Fourth Amendment

<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                           Stein Roe & Farnham CLO I Ltd.,
                           ---------------------------------------------
                           as a Lender by Stein Roe & Farnham Incorporated
                                       As Portfolio Manager


                                   By:
                                       -----------------------------------------

                                       as --------------------------------------



                                       By: /s/ Brian W. Good
                                       ----------------------------------------
                                       Name:  Brian W. Good
                                              ----------------------------------
                                       Title: Sr. Vice President &
                                              ----------------------------------
                                              Portfolio Manager
                                              ----------------------------------




                       Signature Page to Fourth Amendment




<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                           ELC (Cayman) Ltd. 1999-III,
                           ---------------------------------------------
                           as a Lender

                                   By: /s/ Adrienne Musgnug
                                      -----------------------------------------

                                       Name:  Adrienne Musgnug
                                              ----------------------------------
                                       Title: Director
                                              ----------------------------------




                       Signature Page to Fourth Amendment




<PAGE>
Signature Page to that certain Fourth Amendment dated as of the date first
stated above, among Sygnet Wireless, Inc. (successor by merger to Dobson/Sygnet
Operating Company), as Borrower, Bank of America, N.A. (successor to
NationsBank, N.A.), as Administrative Agent, Required Lenders, and Guarantors.



                           K2H Cypress Tree - 1 LLC,
                           ---------------------------------------------
                           as a Lender


                                       By: /s/ Peter Chin
                                       ----------------------------------------
                                       Name:  Peter Chin
                                              ----------------------------------
                                       Title: Authorized Agent
                                              ----------------------------------


                       Signature Page to Fourth Amendment