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                                                                     Exhibit 4.5

                          THIRD SUPPLEMENTAL INDENTURE

Supplemental Indenture (this "Supplemental Indenture"), dated as of January 12,
2001, by and among Orius Information Technologies LLC, a Florida limited
liability company ("Orius Information"), Orius Telecom Services, Inc. ("Orius
Telecom"), Orius Holdings, Inc., a Florida corporation ("Orius Holdings"), Orius
Broadband Services, Inc., a Florida corporation ("Orius Broadband"), Orius
Telecommunication Services, Inc., a Florida corporation ("Orius
Telecommunications"), Orius Central Office Services, Inc., a Florida corporation
("Orius Central"), Orius Telecom Products, Inc., a Florida corporation ("Orius
Products"), Orius Integrated Premise Services, Inc., a Florida corporation
("Orius Premise"), and QMW Communications, Inc., a Florida corporation ("QMW,"
and together with Orius Information, Orius Holdings, Orius Telecom, Orius
Broadband, Orius Telecommunications, Orius Central, Orius Products and Orius
Premise, the "Guaranteeing Subsidiaries"), NATG Holdings, Inc., a Delaware
limited liability company ("NATG"), Orius Capital Corp., a Delaware corporation
(together with NATG, the "Issuers"), Orius Corp., a Florida corporation
("Parent"), the subsidiaries of Parent who are guarantors under the Indenture
(as hereinafter defined) as of the date hereof (together with Parent, the
"Original Guarantors") and United States Trust Company of New York, as trustee
(the "Trustee") under the Indenture. Capitalized terms used herein without
definition shall have the meanings assigned to them in the Indenture.

         W I T N E S S E T H

         WHEREAS, the Issuers and the Original Guarantors have previously
executed and delivered to the Trustee an indenture (as supplemented from time to
time, the "Indenture"), dated as of February 9, 2000, providing for the issuance
of an aggregate principal amount of up to $300,000,000 of 12 3/4% Senior
Subordinated Notes due 2010;

         WHEREAS, the Indenture provides that the Guaranteeing Subsidiaries
shall execute and deliver to the Trustee a supplemental indenture pursuant to
which the Guaranteeing Subsidiaries shall unconditionally guarantee all of the
Issuers' obligations under the Securities and the Indenture on the terms and
conditions set forth in the Indenture; and

         WHEREAS, pursuant to Section 9.1 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture.

         NOW THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the parties
hereto mutually covenant and agree for the equal and ratable benefit of the
Holders of the Securities as follows:

         1. AGREEMENT TO GUARANTEE. The Guaranteeing Subsidiaries hereby agree
as follows:

(a)         Along with all Guarantors named in the Indenture, to jointly and
            severally, unconditionally and irrevocably guarantee, on a senior
            subordinated basis (each such guarantee to be referred to herein as
            a "Note Guarantee") to each Holder of a Security authenticated and
            delivered by the Trustee and to the Trustee and its successors and
            assigns, irrespective of the validity and enforceability of the
            Indenture, this Supplemental Indenture, the Securities or the
            obligations of the Issuers or any other Guarantors to the Holders or
            the Trustee hereunder or thereunder, that: (i) the principal of,
            premium, if any, and interest on the Securities shall be duly and
            punctually paid in full when due, whether at maturity, upon
            redemption at the option of Holders pursuant to the provisions of
            the Securities relating thereto, by acceleration or otherwise, and
            interest on the overdue principal and (to the extent permitted by
            law) interest, if any, on the Securities and all other obligations
            of the Issuers or the Guarantors to the Holders or the Trustee
            hereunder or thereunder (including amounts due the Trustee under
            Section 7.7 of the Indenture) and all other obligations shall be
            promptly paid in full or performed, all in accordance with the terms
            hereof and thereof; and (ii) in case of any extension of time of
            payment or renewal of any Securities or any of such other
            obligations, the same shall be promptly paid in full when due or
            performed in accordance with the terms of the extension or renewal,
            whether at maturity, by acceleration or otherwise. Failing payment
            when due of any amount so guaranteed, or failing performance of any
            other obligation of the Issuers to the Holders under the Indenture
            or under the


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            Securities, for whatever reason, each Guaranteeing Subsidiary shall
            be obligated to pay, or to perform or cause the performance of, the
            same immediately. An Event of Default under the Indenture or the
            Securities shall constitute an event of default under this Note
            Guarantee, and shall entitle the Holders of Securities to accelerate
            the obligations of the Guaranteeing Subsidiaries hereunder in the
            same manner and to the same extent as the obligations of the
            Issuers.

(b)         The Guaranteeing Subsidiaries' obligations hereunder shall be
            unconditional, irrespective of the validity, regularity or
            enforceability of the Securities or this Supplemental Indenture, the
            absence of any action to enforce the same, any waiver or consent by
            any Holder of the Securities with respect to any provisions hereof
            or thereof, any release of any other Guarantor, the recovery of any
            judgment against an Issuer, any action to enforce the same, whether
            or not a Guarantee is affixed to any particular Security, or any
            other circumstance which might otherwise constitute a legal or
            equitable discharge or defense of a Guarantor. Each of the
            Guaranteeing Subsidiaries hereby waive the benefit of diligence,
            presentment, demand of payment, filing of claims with a court in the
            event of insolvency or bankruptcy of an Issuer, any right to require
            a proceeding first against an Issuer, protest, notice and all
            demands whatsoever and covenants that its Note Guarantee shall not
            be discharged except by complete performance of the obligations
            contained in the Securities, the Indenture and this Note Guarantee.
            This Note Guarantee is a guarantee of payment and not of collection.
            If any Holder or the Trustee is required by any court or otherwise
            to return to the Issuers or to any Guarantor, or any custodian,
            trustee, liquidator or other similar official acting in relation to
            an Issuer or such Guarantor, any amount paid by an Issuer or such
            Guarantor to the Trustee or such Holder, this Note Guarantee, to the
            extent theretofore discharged, shall be reinstated in full force and
            effect. Each Guarantor further agrees that, as between it, on the
            one hand, and the Holders of Securities and the Trustee, on the
            other hand, (i) subject to the provisions hereof, the maturity of
            the obligations guaranteed hereby may be accelerated as provided in
            Article Six of the Indenture for the purposes of this Note
            Guarantee, notwithstanding any stay, injunction or other prohibition
            preventing such acceleration in respect of the obligations
            guaranteed hereby, and (ii) in the event of any acceleration of such
            obligations as provided in Article Six of the Indenture, such
            obligations (whether or not due and payable) shall forthwith become
            due and payable by the Guaranteeing Subsidiaries for the purpose of
            this Note Guarantee.

(c)         Each Guaranteeing Subsidiary that makes a payment or distribution
            under a Note Guarantee shall be entitled to a contribution from each
            other Guarantor on a PRO RATA basis, based on the net assets of each
            Guarantor, determined in accordance with GAAP.

(d)         The Obligations of each Guaranteeing Subsidiary under its Note
            Guarantee are limited to the maximum amount which, after giving
            effect to all other contingent and fixed liabilities of such
            Guaranteeing Subsidiary (including its guarantee of obligations in
            respect of the Senior Secured Credit Agreement and any other
            Guarantor Senior Debt), and after giving effect to any collections
            from or payments made by or on behalf of any other Guarantor in
            respect of the obligations of such other Guarantor under its
            Guarantee or pursuant to its contribution obligations under the
            Indenture, will result in the obligations of such Guaranteeing
            Subsidiary under the Note Guarantee not constituting a fraudulent
            conveyance or fraudulent transfer under federal or state law.

         2. INCORPORATION OF TERMS OF INDENTURE. The obligations of the
Guaranteeing Subsidiaries under the Note Guarantees shall be governed in all
respects by the terms of the Indenture and shall constitute a Guarantee
thereunder. Each of the parties hereto shall be bound by the terms of the
Indenture as they relate to the Note Guarantees.

         3. NO RECOURSE AGAINST OTHERS. No stockholder, officer, director,
employee or incorporator, past, present or future, or any Guaranteeing
Subsidiary, as such, shall have any personal liability under this Note Guarantee
by reason of his, her or its status as such stockholder, officer, director,
employee or incorporator.

         4. NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK
SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE BUT WITHOUT

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GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT
THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

         5. COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

         6. EFFECT OF HEADINGS. The Section headings herein are for convenience
only and shall not affect the construction hereof.

         7. DISCLAIMER BY TRUSTEE. The Trustee makes no representation as to the
validity of this Supplemental Indenture or the proper authorization or due
execution of this Supplemental Indenture by the Issuers, the Original Guarantors
or the Guaranteeing Subsidiaries.

                                    * * * * *

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                [SIGNATURE PAGE TO SUPPLEMENTAL INDENTURE CONT.]

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

Dated: January 12, 2001       ORIUS CORP.*
                                       ORIUS CAPITAL CORP.*
                                       CATV SUBSCRIBER SERVICES, INC.
                                       CABLEMASTERS CORP.
                                       CHANNEL COMMUNICATIONS, INC.
                                       EXCEL CABLE CONSTRUCTION, INC.
                                       U.S. CABLE, INC.
                                       DAS-CO OF IDAHO, INC.
                                       NETWORK CABLING SERVICES, INC.
                                       NETWORK CABLING HOLDINGS, INC.*
                                       SCHATZ UNDERGROUND CABLE, INC.
                                       COPENHAGEN UTILITIES & CONSTRUCTION, INC.
                                       TEXEL CORPORATION*
                                       LISN COMPANY
                                       ARION SUB, INC.
                                       LISN, INC.
                                       IRWIN TELECOM HOLDINGS, INC.
                                       IRWIN TELECOM SERVICES, INC.
                                       FENIX HOLDINGS, INC.*
                                       FENIX TELECOMMUNICATIONS SERVICES, INC.*
                                       MIDWEST SPLICING & ACTIVATION, INC.
                                       HATTECH, INC.
                                       ORIUS HOLDINGS, INC.*
                                       ORIUS TELECOM SERVICES, INC.*
                                       ORIUS BROADBAND SERVICES, INC.
                                       ORIUS TELECOMMUNICATION SERVICES, INC.
                                       ORIUS CENTRAL OFFICE SERVICES, INC.
                                       ORIUS TELECOM PRODUCTS, INC.
                                       ORIUS INTEGRATED PREMISE SERVICES, INC.
                                       QMW COMMUNICATIONS, INC.

                                       /s/ William J. Mercurio
                                       -----------------------
                                       William J. Mercurio,
                                       Executive Vice President
                                       (President of those companies designated
                                                with an asterix)



                                       FENIX TELECOM SERVICES LIMITED
                                         PARTNERSHIP
                                       By: Fenix Telecommunications Services,
                                           Inc.
                                       Its: General Partner

                                       /s/ William J. Mercurio
                                       -----------------------
                                       William J. Mercurio
                                       President

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     [SIGNATURE PAGE TO SUPPLEMENTAL INDENTURE CONT.]

                                            IRWIN TELECOM SERVICES, L.P.
                                            By: Irwin Telecom Services, Inc.
                                            Its: General Partner

                                            /s/ William J. Mercurio
                                            -----------------------
                                            William J. Mercurio
                                            Executive Vice President

                                            NETWORK COMPREHENSIVE TELECOM, L.P.
                                            By: Network Cabling Services, Inc.
                                            Its: General Partner

                                            /s/ William J. Mercurio
                                            -----------------------
                                            William J. Mercurio
                                            Executive Vice President

                                            NATG HOLDINGS, LLC
                                            By: Orius Corp.
                                            Its: Sole Member

                                            /s/ William J. Mercurio
                                            -----------------------
                                            William J. Mercurio
                                            President

                                            ORIUS INFORMATION TECHNOLOGIES LLC

                                            /s/ William J. Mercurio
                                            -----------------------
                                            William J. Mercurio
                                            President


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                [SIGNATURE PAGE TO SUPPLEMENTAL INDENTURE CONT.]

                                        UNITED STATES TRUST COMPANY OF NEW YORK,
                                          AS TRUSTEE

                                        By:      ILLEGIBLE
                                           ---------------------------------
                                        Name: ________________________

                                        Its: ________________________


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