
                                                                   EXHIBIT 2.5.5

                       ASSUMPTION AND INDEMNITY AGREEMENT

         ASSUMPTION AND INDEMNITY AGREEMENT, dated as of July 2, 1998, by and
among ABLE TELCOM HOLDING CORP. ("Able") and its permitted successors and
assigns (collectively with Able, "INDEMNITORS"), and WORLDCOM, INC., MFS
COMMUNICATIONS COMPANY, INC., MFS INTELENET, INC., MFS DATANET, INC., MFS
TELECOM, INC., and MFS COMMUNICATIONS, LIMITED and their successors and assigns
(collectively, "ASSUMPTION AGREEMENT BENEFICIARIES").

         Indemnitors and the Assumption Agreement Beneficiaries hereby agree as
follows:

         1. CERTAIN DEFINITIONS. The parties to this Assumption and Indemnity
Agreement hereby agree that, in addition to other terms defined in this
Assumption and Indemnity Agreement, the terms set forth below in this paragraph
1 shall have the following meanings ascribed to them, and that variants and
derivatives of such terms shall have correlative meanings:

         a.       "AETNA" is Aetna Casualty and Surety Company.

         b.       "AETNA BONDS" are those Bonds with respect to which Aetna is
                  listed as the bonding company under the column headed "Bonding
                  Company" on the list of Bonds attached hereto as Exhibit A and
                  all other Bonds, or 

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                  renewals or continuations thereof, which may be already or
                  hereafter issued or executed pursuant to the Aetna Indemnity
                  Agreement.

         c.       "AETNA INDEMNITORS" are, collectively and individually, MFS
                  Communications Company, Inc., MFS Intelenet, Inc., MFS
                  Datanet, Inc., MFS Telecom, Inc., and MFS Communications,
                  Limited, and MFS Network Technologies, Inc. and any other
                  person or entity included within the definition of
                  "Indemnitors" in the Aetna Indemnity Agreement.

         d.       "AETNA INDEMNITY AGREEMENT" is that certain agreement between
                  the Aetna Indemnitors and Aetna, dated December 21, 1994, a
                  copy of which is attached hereto as Exhibit B.

         e.       "ASSUMPTION AGREEMENT" is that agreement set forth herein
                  under the terms of which Indemnitors agree to assume
                  Assumption Agreement Obligations.

         f.       "ASSUMPTION AGREEMENT OBLIGATIONS" is that obligation
                  undertaken by Indemnitors

                  i.       to pay and fully discharge at the Indemnitors'
                           expense all of the liabilities and obligations of the
                           Assumption Agreement Beneficiaries under the Credit
                           Lyonnais Guaranty Agreement; and

                  ii.      to pay and fully discharge at the Indemnitors'
                           expense all of the liabilities and obligations of the
                           Assumption Agreement Beneficiaries under any Surety
                           Indemnity Agreement, Bond, or Contract; and 1.


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                  iii.     at Indemnitors' expense to settle or defend, with
                           counsel approved by Assumption Agreement
                           Beneficiaries (which approval shall not be
                           unreasonably withheld), any actions or proceedings
                           brought against MFS Network Technologies, Inc., or
                           any other Principal, any Surety, and Assumption
                           Agreement Beneficiaries arising out of any Contract,
                           Bond, Surety Indemnity Agreement or the Credit
                           Lyonnais Guaranty Agreement ("Proceedings"), and to
                           pay any judgment entered in any such Proceeding.

         g.       "ASSUMPTION AND INDEMNITY AGREEMENT" is this agreement
                  including all attached Exhibits.

         h.       "BONDS" are those certain bid, payment, performance, permit
                  and/or other bonds listed on Exhibit A and all other bonds
                  which heretofore have been or hereafter are executed and
                  issued under any of the Surety Indemnity Agreements, or any
                  renewal or continuation thereof.

         i.       "CONTRACTS" are the various contracts, including any
                  amendments and change orders, for the work for the various
                  projects listed under the columns headed project number and
                  project name on Exhibit A attached hereto and any other
                  contract with respect to which a Bond has been executed and
                  issued.

         j.       "CREDIT LYONNAIS" is Credit Lyonnais, New York Branch, one of
                  the lenders under that certain Credit Agreement, dated
                  November 1, 1996, 


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                  among Kanas Telecom, Inc., Administrative Agent and Lenders
                  with respect to which the Credit Lyonnais Guaranty Agreement
                  relates.

         k.       "CREDIT LYONNAIS GUARANTY AGREEMENT" is that certain guaranty
                  agreement (a copy of which is attached as Exhibit F) by MFS
                  Communications Company, Inc. in favor of Credit Lyonnais, New
                  York Branch as Administrative Agent for Lenders under that
                  certain Credit Agreement, dated November 1, 1996, among Kansas
                  Telecom, Inc., Administrative Agent for Lenders, and the
                  Lenders dated the 1st day of November, 1996.

         l.       "EVENT OF DEFAULT" is the failure of Indemnitors to perform
                  any Assumption Agreement Obligations.

         m.       "GUARANTY OBLIGATIONS" are those obligations assumed by MFS
                  Communications Company, Inc., under the Credit Lyonnais
                  Guaranty Agreement.

         n.       "GUARANTOR" is MFS Communications Company, Inc., in its
                  capacity as guarantor under the Credit Lyonnais Guaranty
                  Agreement.

         o.       "LOSS" is all reasonable out-of-pocket damages, expenses,
                  costs, the full amount of professional and consulting fees,
                  attorney fees (however incurred, including on appeal),
                  calculated after taking into account any proceeds of insurance
                  received in respect thereto, incurred or paid by Assumption
                  Agreement Beneficiaries, court costs and fees, and interest 


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                  at the rate of 8% on all sums due from the date of Assumption
                  Agreement Beneficiaries' disbursement of said sums, whether or
                  not interest has been awarded by a court, which Assumption
                  Agreement Beneficiaries may sustain, pay, or incur.

         p.       "NORTHERN" is Northern Indemnity, Inc.

         q.       "NORTHERN BONDS" are those Bonds with respect to which
                  Northern is listed as the bonding company under the column
                  headed "Bonding Company" on Exhibit A and all other bonds
                  which may be already or hereafter executed pursuant to the
                  Northern Indemnity Agreement, or any renewal or continuation
                  thereof.

         r.       "NORTHERN INDEMNITORS" are WorldCom, Inc., MFS Communications
                  Company, Inc., MFS Transportation Systems, Inc., MFS
                  TransTech, Inc., MFS Network Technologies, Inc., SIRIT
                  Technologies, Inc. and SIRIT Corp. and any other person or
                  entity included within the definition of "Indemnitors" in the
                  Northern Indemnity Agreement.

         s.       "NORTHERN INDEMNITY AGREEMENT" is that certain agreement
                  between Northern Indemnitors and Northern, a copy of which is
                  attached hereto as Exhibit C.

         t.       "NORTHERN PRINCIPALS" are SIRIT Technologies, Inc. and SIRIT
                  Corp.



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<PAGE>


         u.       "OBLIGEE" is that entity (or its assignee) for whose benefit a
                  Bond was issued.

         v.       "PLEDGE AGREEMENT" is the Stock Pledge Agreement, dated as of
                  July 2, 1998, between Able and MFS Communications Company,
                  Inc.

         w.       "PRINCIPAL" is the Surety Indemnitor identified on a Bond as
                  the principal or contractor.

         x.       "RELIANCE" collectively is Reliance Insurance Company, United
                  Pacific Insurance Company, Reliance National Indemnity Company
                  and Reliance Surety Company.

         y.       "RELIANCE BONDS" are those Bonds with respect to which
                  Reliance or "United Pac" is listed as the bonding company
                  under the column headed "Bonding Company" on Exhibit A and all
                  other bonds which may be already or hereafter are executed or
                  issued pursuant to the Reliance Indemnity Agreement, or any
                  renewal or continuation thereof.

         z.       "RELIANCE INDEMNITORS" are WorldCom, Inc., MFS Communications
                  Company, Inc., MFS Transportation Systems, Inc., MFS
                  TransTech, Inc., and MFS Network Technologies, Inc. and any
                  other person or entity included within the definition of
                  "Contractors" in the Reliance Indemnity Agreement.


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<PAGE>


         aa.      "RELIANCE INDEMNITY AGREEMENT" is that certain agreement
                  between Reliance Indemnitors and Reliance, dated September 22,
                  1997, a copy of which is attached hereto as Exhibit D.

         bb.      "SATISFACTORY RELEASE" as to any Bond and any obligations or
                  liabilities of WorldCom and the Subsidiaries respecting such
                  Bond, is the receipt by WorldCom of (i) written releases, in
                  form and content reasonably satisfactory to WorldCom, whereby
                  all of the parties to whom WorldCom and the Subsidiaries are
                  obligated or otherwise liable respecting such Bond
                  unconditionally, irrevocably, and fully release WorldCom and
                  the Subsidiaries from any obligation or liabilities respecting
                  such Bond, or (ii) other evidence reasonably satisfactory to
                  WorldCom that such Bond and any obligations or liabilities of
                  WorldCom and the Subsidiaries respecting the Bonds have
                  expired in accordance with their terms.

         cc.      "SUBSTITUTED CONTRACT PERFORMANCE" is as defined in paragraph
                  8.

         dd.      "SURETY" is, as appropriate, Aetna, Northern, Reliance, or
                  USF&G and is the party who acts a co-obligor with the
                  Principal on a Bond.

         ee.      "SURETY INDEMNITORS" are Aetna Indemnitors, Reliance
                  Indemnitors, Northern Indemnitors and USF&G Indemnitors.

         ff.      "SURETY INDEMNITY AGREEMENTS" are those certain indemnity
                  agreements identified as Aetna Indemnity Agreement, Reliance


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<PAGE>

                  Indemnity Agreement, Northern Indemnity Agreement and USF&G
                  Indemnity Agreement.

         gg.      "USF&G" is United State Fidelity & Guarantee Company, Fidelity
                  & Guarantee Insurance Company, and Fidelity & Guarantee
                  Insurance Underwriters, Inc.

         hh.      "USF&G BONDS" are those Bonds with respect to which USF&G is
                  listed as the bonding company under the column headed "Bonding
                  Company" on Exhibit A and all other bonds which may be already
                  or hereafter are executed pursuant to the USF&G Indemnity
                  Agreement, or any renewal or continuation thereof.

         ii.      "USF&G INDEMNITORS" are WorldCom, Inc., MFS Network
                  Technologies, Inc., MFS Transportation Systems, Inc., and MFS
                  TransTech, Inc., and any other person or entity included
                  within the definition of "Undersigned" in the USF&G Indemnity
                  Agreement.

         jj.      "USF&G INDEMNITY AGREEMENT" is that agreement between USF&G
                  and USF&G Indemnitors, dated August 18, 1997, a copy of which
                  is attached hereto as Exhibit E.

         2. CONSIDERATION. Contemporaneously herewith Able is purchasing from
MFS Communications Company, Inc. all of the assets and assuming substantially
all of the liabilities of MFS Network Technologies, Inc. pursuant to a Agreement
and Plan of Merger, dated as of April 26, 1998, as amended by an Amendment
thereto, dated as of 


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<PAGE>

July 2, 1998 (the "Merger Agreement"). The execution and delivery of this
Assumption and Indemnity Agreement is an express condition to the closing and
consummation of the transactions contemplated by the Merger Agreement.
Indemnitor hereby acknowledges the receipt and sufficiency of adequate
consideration for Indemnitors' execution, delivery and performance of this
Assumption and Indemnity Agreement including, without limitation, the closing
and consummation of the transactions contemplated by the Merger Agreement and
the covenants and agreements made therein by the parties thereto.

         3. ASSUMPTION AGREEMENT. In consideration of the foregoing and in
consideration of MFS Communications Company, Inc.'s agreement to cause MFS
Network Technologies, Inc. to sell all of the assets of the NT Business (as
defined in the Merger Agreement) under the Merger Agreement, Indemnitors hereby
jointly and severally agree to, and hereby do, assume and agree to pay and fully
discharge at their expense the Assumption Agreement Obligations.

         4. PAYMENT. Payments of amounts due Assumption Agreement Beneficiaries
as a result of an Event of Default shall be made by Indemnitors to Assumption
Agreement Beneficiaries upon demand made by any Assumption Agreement
Beneficiary.

         5. DUTY TO NOTIFY. The Assumption Agreement Beneficiaries agree to
forthwith provide written notice to Indemnitors if any of them has knowledge of
the occurrence of an Event of Default or of circumstances which with the passage
of time will constitute an Event of Default. Notwithstanding anything herein to
the contrary, the failure by Assumption Agreement Beneficiaries to provide the
notice provided for 


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<PAGE>

herein shall not affect the determination of whether an Event of Default has
occurred hereunder nor shall the failure to provide the notice provided for
hereunder relieve Indemnitors of their obligations under this Assumption and
Indemnity Agreement.

         6. ASSUMPTION AGREEMENT BENEFICIARIES RIGHT TO SETTLE, DEFEND. If there
has been an Event of Default, Assumption Agreement Beneficiaries shall have the
exclusive right, in their sole and absolute discretion, to determine whether any
claim, demand, suit or judgment on the Credit Lyonnais Guaranty Agreement or any
Surety Indemnity Agreement shall be paid, settled, defended, prosecuted,
compromised or appealed and to investigate, pay, settle, defend, prosecute,
compromise, or appeal any such claim, demand, suit or judgment. Assumption
Agreement Beneficiaries shall be entitled to reimbursement for any Loss incurred
as a result of having investigated, paid, settled, defended, prosecuted,
compromised or appealed any such claim, demand, suit, or judgment under a good
faith belief that: (a) Assumption Agreement Beneficiaries were or might be
liable therefor; or (b) such payments were necessary or expedient to protect any
of Assumption Agreement Beneficiaries' rights or to avoid or lessen Assumption
Agreement Beneficiaries' liability or alleged liability, whether or not such
liability, necessity or expediency existed and whether or not such payments were
negligent. An itemized statement of Loss sworn to by any officer or authorized
representative of Assumption Agreement Beneficiaries, or voucher or other
evidence of such Loss shall be final, conclusive and binding upon Indemnitors in
any claim or suit and all matters arising between Indemnitors and Assumption
Agreement Beneficiaries. Without in any way limiting the foregoing, Assumption
Agreement Beneficiaries shall make reasonable efforts to provide information to
Indemnitors as to the status of any such claim, demand, suit or judgment.


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<PAGE>



         7. CONTRIBUTION. Indemnitors and Surety Indemnitors who are not also
Assumption Agreement Beneficiaries shall have no rights of contribution, rights
of offset, rights of recoupment, or similar rights by virtue of having performed
any Assumption Agreement Obligation, or any obligation under any Bond, Contract,
or Surety Indemnity Agreement as respects Assumption Agreement Beneficiaries, or
as respects any Contract liability, or Contract funds, or any other obligation
or liability under any agreement between Assumption Agreement Beneficiaries and
Indemnitors or Surety Indemnitors who are not also Assumption Agreement
Beneficiaries.

         8. SUBSTITUTED CONTRACT PERFORMANCE. In the event a Principal
materially fails, refuses, or is unable to observe or perform any of its
material obligations under a Contract, and Indemnitors fail, refuse or, in the
judgment of Assumption Agreement Beneficiaries, are unable to perform Assumption
Agreement Obligations, Assumption Agreement Beneficiaries may, in the exercise
of their reasonable discretion and, upon five days' prior written notice to
Indemnitors, referring specifically to this paragraph 8, take any, some, or all
actions which Assumption Agreement Beneficiaries believe appropriate to attempt
to minimize the Loss which they may have otherwise sustained, including, without
limitation, performing the Contract on behalf of the Principal (herein called
"Substituted Contract Performance") if and to the extent permitted by the
Contract. Any election by Assumption Agreement Beneficiaries to undertake
Substituted Contract Performance, and any undertaking thereof, shall not
release, amend, modify, limit, restrict, or otherwise affect (a) Principals'
obligations under the Contract, or (b) Indemnitors' Assumption Agreement
Obligations, even if the amount of the Loss is increased by any such
undertaking. In the event Assumption Agreement Beneficiaries elect to undertake
Substituted Contract Performance, the affected Principal and Indemnitors shall
fully cooperate with Assumption Agreement Beneficiaries, shall 


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<PAGE>

provide Assumption Agreement Beneficiaries with access to the Principal's books,
records, tools, employees, agents, professionals, suppliers, and subcontractors,
and shall assign to Assumption Agreement Beneficiaries the Contract or other
agreements as Assumption Agreement Beneficiaries reasonably request to
facilitate Assumption Agreement Beneficiaries' efforts to undertake such
Substituted Contract Performance if and to the extent permitted by the Contract.
Assumption Agreement Beneficiaries shall hold confidential information received
by them in the course of such access. Assumption Agreement Beneficiaries shall
be entitled to reimbursement of any Loss incurred by it as a result of
undertaking Substituted Contract Performance and an itemized statement of Loss
sworn to by any officer or authorized representative of Assumption Agreement
Beneficiaries, or voucher or other evidence of such Loss shall be final,
conclusive and binding upon Indemnitors in any claim or suit and all matters
arising between Indemnitors and Assumption Agreement Beneficiaries. Nothing
contained in this Assumption and Indemnity Agreement shall require Assumption
Agreement Beneficiaries to undertake any Substituted Contract Performance.

         9. SECURITY. As collateral security for Indemnitors' undertakings
hereunder, Able hereby agrees to deliver to Assumption Agreement Beneficiaries
the Pledge Agreement.

         10. TERM/NO RELEASE. The term of this Assumption and Indemnity
Agreement shall extend until Satisfactory Releases shall have been obtained for
all of the Bonds. Notwithstanding the generality of the foregoing, the
termination of this Assumption and Indemnity Agreement shall not release, amend,
modify, limit, restrict, or otherwise affect Indemnitors' indemnity obligations,
covenants, or agreements hereunder, which obligations, covenants, and agreements
shall survive forever.


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         11. NO WAIVER. No failure on the part of Assumption Agreement
Beneficiaries to exercise, and no delay in exercising, any right, power or
remedy hereunder shall operate as a waiver thereof, nor shall any single or
partial exercise of any right, power, or remedy by Assumption Agreement
Beneficiaries preclude any other or further exercise thereof or the exercise of
any other right, power, or remedy.

         12. NOTICES. All notices or other communications which are required or
permitted herein shall be in writing and sufficient if delivered personally, or
sent by overnight air courier, or sent by facsimile followed by overnight air
courier, addressed as follows:

         If to Assumption Agreement
         Beneficiaries:                 WorldCom, Inc.
                                        515 East Amite Street
                                        Jackson, Mississippi   39201
                                        Attention: David Roberts

         with copies to:                Skadden, Arps, Slate, Meagher & Flom LLP
                                        919 Third Avenue
                                        New York, New York 10022 and
                                        Attention:  Randall Doud, Esq., and



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<PAGE>


                                      Fraser, Stryker, Vaughn, Meusey, Olson,
                                      Boyer & Bloch, P.C.
                                      500 Energy Plaza
                                      409 South 17th Street
                                      Omaha, Nebraska 68102
                                      Attention: Robert M. Yates

         If to Indemnitors:           Able Telcom Holding Corp.
                                      1601 Forum Place, Suite 1110
                                      West Palm Beach,  Florida 33401
                                      Attention: Gideon Taylor

         with a copy to:              Gunster, Yoakley, Valdes-Fauli
                                      & Stewart, P.A.
                                      Phillips Point
                                      777 Flagler Dr., Suite 500 East
                                      West Palm Beach, Florida. 33401-6194
                                      Attention:  Michael V. Mitrione

or at such other address as the party to whom notice is to be given may have
furnished to the other party in writing in accordance herewith. Any such
communication shall be deemed to have been given when delivered if delivered
personally or sent by facsimile, or on the first business day after dispatch if
sent by overnight air courier.

         13. FURTHER ASSURANCES. Indemnitors agree to execute and deliver such
additional conveyances, assignments, agreements and instruments, as Assumption


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<PAGE>

Agreement Beneficiaries may at any time reasonably request in connection with
the administration or enforcement of this Assumption and Indemnity Agreement or
any part thereof or in order better to assure and confirm unto Assumption
Agreement Beneficiaries their rights, powers, and remedies hereunder as
determined by legal counsel for Assumption Agreement Beneficiaries.

         14. ASSIGNMENT; BINDING AGREEMENT. None of the parties to this
Assumption Agreement may assign or delegate this Assumption and Indemnity
Agreement or its obligations, covenants or agreements hereunder to any person or
entity without the prior written approval of the parties. This Assumption and
Indemnity Agreement, and the terms, covenants and conditions hereof, shall be
binding upon and inure to the benefit of the parties hereto and permitted
successors and assigns.

         15. AMENDMENTS. Neither this Assumption and Indemnity Agreement nor any
provisions hereof may be amended, modified, waived, discharged or terminated
orally, but, rather, only by an instrument in writing duly signed by or on
behalf of Assumption Agreement Beneficiaries.

         16. SEVERABILITY. If any term or provision of this Assumption and
Indemnity Agreement or the application thereof to any person or circumstances
shall to any extent be invalid or unenforceable, the remainder of this
Assumption and Indemnity Agreement or the application of such term or provision
to persons or circumstances other than those as to which it is held invalid or
unenforceable shall not be effected hereby, and each term and provision of this
Assumption and Indemnity Agreement shall be valid and enforced to the fullest
extent permitted by law.


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         17. COUNTERPARTS. This Assumption and Indemnity Agreement may be
executed in one or more counterparts, each of which shall be an original but all
of which, taken together, shall constitute a single agreement.

         18. GOVERNING LAW. This Assumption and Indemnity Agreement shall be
governed in all respects, including validity, interpretation and effect, by the
laws of the State of Delaware and the United States of America, without regard
to the principles of conflict of laws thereof, and may only be enforced in the
courts of the State of Delaware, or the United States District Court for the
District of Delaware, the jurisdiction of which courts each Party hereby
irrevocably subjects itself to.







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<PAGE>

         IN WITNESS WHEREOF, the undersigned has caused this Agreement to be
duly executed and delivered as of the date first above written.

                                    ABLE TELCOM HOLDING CORP.

                                    By:    /S/ FRAZIER L. GAINES
                                       --------------------------------------
                                       Frazier L. Gaines, President and CEO

                                    WORLDCOM, INC.

                                    By:  /S/ JOHN SIDGMORE
                                       --------------------------------------

                                    MFS COMMUNICATIONS
                                    COMPANY, INC.

                                    By:  /S/ JOHN SIDGMORE
                                       --------------------------------------

                                    MFS INTELENET, INC.

                                    By:  /S/ JOHN SIDGMORE
                                       --------------------------------------

                                    MFS DATANET, INC.

                                    By:  /S/ JOHN SIDGMORE
                                       --------------------------------------

                                    MFS TELECOM, INC.

                                    By:  /S/ JOHN SIDGMORE
                                       --------------------------------------

                                    MFS COMMUNICATIONS,
                                    LIMITED

                                    By:  /S/ JOHN SIDGMORE
                                       --------------------------------------


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EXHIBITS (Omitted)

Exhibit A - List of Bonds 
Exhibit B - Aetna Indemnity Agreement 
Exhibit C - Northern Indemnity Agreement 
Exhibit D - Reliance Indemnity Agreement 
Exhibit E - USF&G Indemnity Agreement 
Exhibit F - Credit Lyonnais Guaranty Agreement

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

The Company agrees to provide copies of any omitted exhibit(s) supplementally to
the Commission upon request.



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