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                                                                     EXHIBIT 4.5

               THIS SUPPLEMENTAL INDENTURE, dated as of May 28, 1996, is between
PRONET INC., a corporation duly organized and existing under the laws of the
State of Delaware (the "Company"), and FIRST INTERSTATE BANK OF TEXAS, N.A.,
acting as Trustee under the Existing Indenture referred to below (the
"Trustee").

                              W I T N E S S E T H:

               WHEREAS, the Company duly authorized the execution and delivery
of an indenture dated as of June 15, 1995 (the "Existing Indenture") to provide
for the issuance of its 11-7/8% Senior Subordinated Notes due 2005 (the
"Securities"), up to principal amount of $100,000,000;

               WHEREAS, the Company has duly authorized the execution and
delivery of an indenture (the "New Indenture") to provide for the issuance of
Senior Subordinated Notes due 2006 up to principal amount of $100,000,000;

               WHEREAS, the Company has duly authorized the execution and
delivery of this Supplemental Indenture deleting certain definitions and
amending certain covenants and events of default so as to make the terms and
conditions of the Existing Indenture conform to the terms and conditions of the
New Indenture;

               WHEREAS, Section 9.2 of the Indenture authorizes the Company and
the Trustee, in accordance with the terms thereof, to enter into a supplement to
the Existing Indenture with the consent of the holders of the Securities;

               WHEREAS, the Company has requested the Trustee, and the Trustee
has agreed, to join in the execution of this Supplemental Indenture pursuant to
Section 9.2 of the Existing Indenture on the terms and subject to the conditions
set forth below; and

               WHEREAS, all acts and things necessary to make this Supplemental
Indenture a valid agreement of the Company according to its terms have been done
and performed, and the execution and delivery of this Supplemental Indenture
have in all respects been duly authorized.

               In consideration of the premises, of the purchase and acceptance
of the Securities by the Holders thereof and of the sum of one dollar duly paid
to it by the Trustee at the execution and delivery of these presents, the
receipt whereof is hereby acknowledged, the Company covenants and agrees with
the Trustee for the equal and proportionate benefit of the respective Holders
from time to time of the Securities or of any series thereof, as follows:

               SECTION 1.    DEFINED TERMS

               1.1 Defined Terms. Capitalized terms herein, not otherwise
defined, shall have the meanings given them in the Existing Indenture.



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               SECTION 2.    AMENDMENTS

               2.1    Amendment to Section 1.1 of the Indenture. Section 1.1 of
the Existing Indenture is hereby amended by deleting the definitions of
"Capital Expenditures" and "Free Cash Flow" in their entirety.

               2.2    Amendment to Section 4.9 of the Existing Indenture. 
Section 4.9 of the Existing Indenture is hereby amended by (a) deleting the
first two paragraphs of such Section in their entirety and (b) inserting in
lieu thereof the following:

                      "The Company may not, and may not permit its Subsidiaries
               to, directly or indirectly, create, incur, assume, become liable
               for or guarantee the payment of (collectively, "incur") any Debt
               (including Acquired Debt), provided, however, that the Company
               may incur Debt (including Acquired Debt) and may permit a
               Subsidiary to incur Acquired Debt if immediately thereafter the
               ratio of the aggregate principal amount of Debt of the Company
               and its Subsidiaries outstanding as of the most recent available
               quarterly or annual balance sheet to the product of four times
               Pro Forma Consolidated Cash Flow for the preceding full fiscal
               quarter, determined on a pro forma basis as if any such Debt had
               been incurred and the proceeds thereof had been applied at the
               beginning of such fiscal quarter, would be less than 6.0 to 1.

                      Notwithstanding the foregoing, the Company may, and may
               permit its Subsidiaries to, incur the following without regard to
               the foregoing limitation and without duplication: (i) Debt of the
               Company under the Credit Facility in an aggregate principal
               amount not to exceed $125 million at any one time outstanding;
               (ii) Guarantees by Subsidiaries of Debt of the Company under the
               Credit Facility; (iii) Debt of the Company evidenced by the
               Securities; (iv) Debt owed by the Company to any wholly owned
               Subsidiary of the Company or owed by any wholly owned Subsidiary
               of the Company to the Company or any other wholly owned
               Subsidiary of the Company (but only so long as such Debt is held
               by the Company or such wholly owned Subsidiary); (v) Debt
               outstanding on the date the Securities are originally issued
               under the indenture; (vi) Permitted Deferred Payments; (vii) Debt
               arising from the honoring by a bank or other financial
               institution of a check, draft or similar instrument drawn against
               insufficient funds in the ordinary course of business, provided
               that such Debt is extinguished within two Business Days of its
               occurrence; (viii) Refinancing Debt; and (ix) renewals of
               Guarantees permitted by clause (ii) above."

               2.3    Amendment to Section 4.11 of the Existing Indenture.
Section 4.11 of the Existing Indenture is hereby amended by (a) deleting
Section 4.11 in its entirety and (b) inserting in lieu thereof the following:


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                      "Section 4.11. Limitations on Restricted Payments. The
               Company may not, and may not permit any of its Subsidiaries to,
               (i) directly or indirectly, declare or pay any dividend, or make
               any distribution, in respect of its Capital Stock or to the
               holders thereof (including pursuant to a merger or consolidation
               of the Company, but excluding any dividends or distributions
               payable solely in shares of its Capital Stock (other than
               Redeemable Stock) or in options, warrants or other rights to
               acquire its Capital Stock (other than Redeemable Stock)), other
               than dividends or distributions payable to the Company or any
               wholly owned Subsidiary of the Company, or by a Subsidiary of the
               Company to a holder who is not the Company or a wholly owned
               Subsidiary of the Company, provided that such dividend or
               distribution is paid to all of the holders of the Capital Stock
               of the payor of such dividend, pro rata in accordance with their
               respective interests, (ii) directly or indirectly, purchase,
               redeem or otherwise acquire or retire for value (a) any Capital
               Stock of the Company or any Related Person or (b) any options,
               warrants, or rights to purchase or acquire shares of Capital
               Stock of the Company or any Related Person, (iii) make any loan,
               advance, capital contribution to or investment in, or payment on
               a Guarantee of any obligation of any Affiliate or any Related
               Person (other than the Company or a Subsidiary of the Company),
               inclusive of any loan, advance, capital contribution to or
               investment in, or payment on a Guarantee of any obligation of any
               Affiliate or Related Person by the Company pursuant to a
               transaction whereby any such Affiliate or Related Person becomes
               an Affiliate or Related Person, but exclusive of any loan,
               advance, capital contribution to or investment in, or payment on
               a Guarantee of any obligation of, any Person by the Company or a
               Subsidiary of the Company pursuant to a transaction whereby any
               such Person becomes a Subsidiary of the Company, in each case
               unless otherwise prohibited by the terms of this Indenture, or
               (iv) redeem, defease, repurchase, retire or otherwise acquire or
               retire for value prior to any scheduled maturity, repayment or
               sinking fund payment (other than with the proceeds of Refinancing
               Debt), Debt of the Company which is subordinate in right of
               payment to the Securities (each of clauses (i) through (iv) being
               a "Restricted Payment"), if at the time of such Restricted
               Payment, or after giving effect thereto: (1) an Event of Default,
               or an event that with the lapse of time or the giving of notice,
               or both, would constitute an Event of Default, shall have
               occurred and be continuing, (2) the Company could not incur $1.00
               of additional Debt under the first paragraph of Section 4.9
               hereof, or (3) the aggregate of all Restricted Payments from the
               date of the Indenture exceeds the sum of: (a) the remainder of
               (x) 100% of cumulative Consolidated Cash Flow after June 30, 1996
               through the last day of the last full fiscal quarter immediately
               preceding such Restricted Payment for which quarterly or annual
               financial statements of the Company are available minus (y) the
               product of 2.0 times cumulative Consolidated Fixed Charges after
               June 30, 1996 through the last day of the last full fiscal
               quarter immediately preceding such Restricted Payment for which
               quarterly or annual financial statements of the Company are
               available; and 



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               (b) 100% of the aggregate net proceeds from the issuance, after 
               June 30, 1996, of Capital Stock (other than Redeemable Stock) of 
               the Company and options, warrants or other rights on Capital 
               Stock (other than Redeemable Stock) of the Company and the 
               principal amount of Debt of the Company that has been converted, 
               after June 30, 1996, into Capital Stock (other than Redeemable 
               Stock) of the Company.

                      The foregoing provision will not be violated by reason of
               (i) the payment of any dividend within 60 days after declaration
               thereof if at the declaration date such payment would have
               complied with the foregoing provision; (ii) the purchase,
               redemption, acquisition or retirement of any shares of Capital
               Stock of the Company in exchange for, or out of the net proceeds
               of the substantially concurrent sale (other than to a Subsidiary
               of the Company) of, other shares of Capital Stock (other than
               Redeemable Stock) of the Company; (iii) the purchase, redemption,
               defeasance or other acquisition or retirement of Debt of the
               Company which is subordinate in right of payment to the
               Securities, in exchange for, by conversion into, or out of the
               net proceeds of, a substantially concurrent (a) issue or sale
               (other than to a Subsidiary) of Capital Stock (other than
               Redeemable Stock) of the Company, or (b) incurrence of
               Refinancing Debt with respect to such subordinated Debt; or (iv)
               investments in telecommunications businesses in an aggregate
               amount not exceeding $20.0 million; provided that no Default or
               Event of Default shall have occurred and be continuing at the
               time, or shall occur as a result, of any of the actions
               contemplated in clauses (ii) and (iii) above. Any payment made
               pursuant to clauses (i) through (iii) (other than subclause
               (iii)(b)) of this paragraph shall be a Restricted Payment for
               purposes of calculating aggregate Restricted Payments under the
               preceding paragraph."

                      2.4    Amendment to Section 6.1 of the Existing Indenture.
               Section 6.1 of the Existing Indenture is hereby amended by (a)
               deleting paragraphs (g) and (h) of such Section in their entirety
               and (b) inserting in lieu thereof the following:       

                      "(g) final judgment or judgments for the payment of money
               which in the aggregate at any one time exceeds $5 million shall
               be rendered against the Company or any Subsidiary of the Company
               by a court of competent jurisdiction and shall not have been
               vacated, discharged, satisfied or stayed within 60 days after
               such judgment becomes final and nonappealable; or


                      (h) a default shall have occurred under any bonds,
               debentures, notes or other evidences of indebtedness of the
               Company or any Subsidiary of the Company or under any mortgages,
               indentures or instruments under which there may be issued or by
               which there may be secured or evidenced any indebtedness by the
               Company or any Subsidiary of the Company, in any case with a
               principal amount of at least $5 million outstanding, and such
               indebtedness already is due and payable 


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               in full or such default has resulted in the acceleration of the
               maturity of such indebtedness, in each case after a period of 
               five days during which period such default shall not have been 
               cured or such acceleration shall not have been rescinded."


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               IN WITNESS WHEREOF, ProNet Inc. has caused this Supplemental
Indenture to be signed, and acknowledged by its President, its Chairman of the
Board, one of its Vice Presidents, its Chief Financial Officer or its Treasurer,
and its corporate seal to be affixed hereunto, and the same to be attested by
its Secretary, its Assistant Secretary or one of its Attesting Secretaries, and
First Interstate Bank of Texas, N.A., as Trustee, has caused this Supplemental
Indenture to be signed and acknowledged by one of its authorized officers, and
its corporate seal to be affixed hereunto, and the same to be attested by one of
its authorized officers, as of the day and year first above written.

                                               PRONET INC.


                                               By:
                                                  --------------------------
                                                      Vice President

Attest:


---------------------------------
Assistant Secretary

                                               FIRST INTERSTATE BANK OF TEXAS,
                                                  N.A., as Trustee


                                               By:
                                                  ------------------------------
                                                      Jeffrey D. Dunbar
                                                      Assistant Vice President
                                                      Corporate Trust Officer

Attest:


----------------------------------
Christina Faith
Assistant Vice President
Corporate Trust Officer




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