<PAGE>

                                                              EXHIBIT 10.79

                                    GUARANTY

         THIS GUARANTY, dated as of April 12, 2000 (as amended, restated, and
otherwise modified from time to time, this "Guaranty"), is made by
___________________________ ("Guarantor"), of the obligations of STAR
Telecommunications, Inc. ("Debtor"), under the WorldCom Documents, as defined
below, by and between Debtor and MCI WORLDCOM NETWORK SERVICES, INC., a Delaware
corporation ("WorldCom"), as agent for itself and MCI WORLDCOM, INC., its
affiliates and subsidiaries (collectively, the "WorldCom Entities").

                              W I T N E S S E T H:

         WHEREAS, WorldCom provides telecommunications services to Debtor,
Guarantor and certain of their respective Subsidiaries pursuant to the Service
Agreements; and

         WHEREAS, Debtor is in default to WorldCom for, INTER ALIA, failure to
pay its obligations to WorldCom in a timely manner (the "Past Due
Indebtedness"); and

         WHEREAS, Debtor and WorldCom have agreed to restructure certain of the
Past Due Indebtedness due to WorldCom as of February 3, 2000, in the form of a
Promissory Note in the principal amount of $56,017,698.87, of even date herewith
(the "Note"), which has been executed and delivered by Debtor to WorldCom; and

         WHEREAS, Guarantor has determined that the execution, delivery, and
performance of this Guaranty is necessary and convenient to the conduct,
promotion, and attainment of Guarantor's business; and

         WHEREAS, Guarantor desires to induce WorldCom to accept delivery of the
Note, extend the term of the obligations evidenced by the Note, and otherwise
restructure the credit relationship between Debtor and WorldCom to facilitate
the potential merger between Debtor and World Access, Inc., all of which are
reasonably expected to benefit, directly or indirectly, Guarantor.

          NOW, THEREFORE, in consideration of the foregoing premises and in
order to, INTER ALIA, induce WorldCom to agree to the financial restructuring
with the Debtor, Guarantor hereby agrees as follows:

          1.       DEFINITIONS. Unless otherwise defined in this Agreement,
terms used herein shall have the meanings set forth in the Workout Agreement,
or Credit Agreement, in that order. Unless the context indicates otherwise or
the terms are otherwise defined herein, definitions in the Uniform Commercial
Code as enacted in the State of Oklahoma (the "UCC") apply to words and
phrases in this Agreement. "Debtor" includes, without limitation, such
Person, such Person's heirs, successors and assigns, such Person as a
debtor-in-possession, and any receiver, trustee, liquidator, conservator,
custodian, or similar party appointed for such Person or all or substantially
all of its assets under any law.

<PAGE>

          2.       GUARANTY.


                   (a)   Guarantor  hereby  unconditionally  guarantees to
WorldCom the punctual payment and performance of, and promises to pay and
perform when due, whether at stated maturity, by acceleration, or otherwise,
all of the Obligations, and agrees to pay any and all reasonable expenses
(including reasonable attorneys' fees and expenses) incurred in enforcement
or collection of all or any part thereof, whether such obligations,
indebtedness, and liabilities are direct, indirect, fixed, contingent, joint,
several, or joint and several, and in enforcement of any rights under this
Guaranty.

                   (b)   Anything  contained  in this  Guaranty  to the
contrary  notwithstanding,  the obligations of Guarantor hereunder shall be
limited to a maximum aggregate amount equal to the largest amount that would
not render its obligations hereunder subject to avoidance as a fraudulent
transfer or conveyance under Section 548 of Title 11 of the United States
Code or any applicable provisions of comparable state law (collectively, the
"Fraudulent Transfer Laws"), in each case after giving effect to all other
liabilities of Guarantor, contingent or otherwise, that are relevant under
the Fraudulent Transfer Laws (specifically excluding, however, any
liabilities of Guarantor in respect of intercompany indebtedness to Debtor or
other affiliates of Debtor to the extent that such indebtedness would be
discharged in an amount equal to the amount paid by Guarantor hereunder) and
after giving effect as assets, subject to Paragraph 5(a) hereof, to the value
(as determined under the applicable provisions of the Fraudulent Transfer
Laws) of any rights to subrogation or contribution of Guarantor pursuant to
(i) applicable law or (ii) any agreement providing for an equitable
allocation among Guarantor and other affiliates of Debtor of obligations
arising under guaranties by such parties.

          3.       GUARANTY  ABSOLUTE.   This  is  a  guaranty  of  payment
and  performance  and  not  of collection. The liability of Guarantor
hereunder shall be joint and several with any other guarantors of the
Obligations guaranteed hereby. Guarantor guarantees that the Obligations will
be paid strictly in accordance with the terms of the WorldCom Documents,
regardless of any applicable law, regulation, or order now or hereafter in
effect in any jurisdiction affecting any of such terms or the rights of
WorldCom with respect thereto. The obligations and liabilities of Guarantor
hereunder are independent of the obligations of Debtor under the WorldCom
Documents and any applicable law, to the extent that Guarantor's obligations
to make such payments are not in violation of any applicable law. The
liability of Guarantor under this Guaranty shall be absolute and
unconditional irrespective of:

                   (a)  the taking or  accepting  of any other  security or
guaranty  for any or all of the Obligations;

                   (b)  any  increase,  reduction,  or payment in full at any
time or from time to time of any part of the Obligations;

                   (c)  any lack of validity or enforceability of the any of
the WorldCom  Documents or any other agreement or instrument relating
thereto, including but not limited to the

                                    2

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unenforceability of all or any part of the Obligations by reason of the fact
that (i) the act of creating the Obligations, or any part thereof, is ULTRA
VIRES, (ii) the officers creating same acted in excess of their authority, or
(iii) for any other reason;

                   (d)  any lack of  corporate  power of Debtor or any other
Person at any time liable for the payment of any or all of the Obligations;

                   (e)  any Debtor Relief Laws  affecting the rights of
creditors  generally  involving Debtor, Guarantor, or any other Person
obligated on any of the Obligations;

                   (f)  any renewal, compromise, extension,  acceleration, or
other change in the time, manner, or place of payment of, or in any other
term of, all or any of the Obligations; any adjustment, indulgence,
forbearance, or compromise that may be granted or given by WorldCom to
Debtor, Guarantor, or any Person at any time liable for the payment of any or
all of the Obligations; or any other modification, amendment, or waiver of or
any consent to departure from any of the WorldCom Documents or any other
agreement or instrument relating thereto without notification of Guarantor
(the right to such notification being herein specifically waived by
Guarantor);

                   (g)  any exchange, release, sale,  subordination, or
non-perfection of any Collateral or Lien thereon or any lack of validity or
enforceability or change in priority, destruction, reduction, or loss or
impairment of value of any Collateral or Lien thereon;

                   (h)  any release or amendment or waiver of or consent to
departure from any other guaranty for all or any of the Obligations;

                   (i)  the failure by WorldCom to make any demand upon or to
bring any legal, equitable, or other action against Debtor or any other
Person (including, without limitation, Guarantor), or the failure or delay by
WorldCom to, or the manner in which WorldCom shall, proceed to exhaust rights
against any direct or indirect security for the Obligations;

                   (j)  the existence of any claim, defense, set-off, or
other rights which Debtor or Guarantor may have at any time against Debtor,
WorldCom, or Guarantor, or any other Person, whether in connection with this
Guaranty, the other WorldCom Documents, the transactions contemplated
thereby, or any other transaction;

                   (k)  any failure of WorldCom to notify Guarantor of any
renewal, extension, or assignment of the Obligations or any part thereof, or
the release of any security, or of any other action taken or refrained from
being taken by WorldCom, it being understood that WorldCom shall not be
required to give Guarantor any notice of any kind under any circumstances
whatsoever with respect to or in connection with the Obligations;

                   (l)  any payment by Debtor to WorldCom is held to
constitute a preference  under any Debtor Relief Law or if for any other
reason WorldCom is required to refund such payment or pay the amount thereof
to another Person; or

                                     3

<PAGE>

                   (m)  any other circumstance which might otherwise
constitute a defense  available to, or a discharge of, Debtor, Guarantor, any
other guarantor or other Person liable on the Obligations, including, without
limitation, any defense by reason of any disability or other defense of
Debtor, or the cessation from any cause whatsoever of the liability of
Debtor, or any claim that Guarantor's obligations hereunder exceed or are
more burdensome than those of Debtor.

         This Guaranty shall continue to be effective or be reinstated, as the
case may be, if at any time any payment of any of the Obligations is rescinded
or must otherwise be returned by WorldCom or any other Person as a result of the
insolvency, bankruptcy, or reorganization of Debtor or Guarantor or otherwise,
all as though such payment had not been made.


         4.   WAIVER. Guarantor hereby waives: (a) any incapacity, lack of
authority, death, or disability of Guarantor or any other Person or entity;
(b) any failure of WorldCom to commence an action against Debtor or any other
Person or entity (including, without limitation, other guarantors, if any),
or to file or enforce a claim against the estate (either in administration,
bankruptcy, or any other proceeding) of Debtor or any other Person or entity,
whether or not demand is made upon WorldCom to file or enforce such claim;
(c) any failure of WorldCom to give notice of the existence, creation, or
incurring of any new or additional indebtedness or other obligation or of any
action or nonaction on the part of any other Person or entity in connection
with any of the WorldCom Documents or any obligation hereby guaranteed; (d)
any failure on the part of WorldCom to ascertain the extent or nature of the
Collateral or any insurance or other rights with respect thereto, or the
liability of any party liable for the WorldCom Documents or the obligations
evidenced or secured thereby, or any failure on the part of WorldCom to
disclose to Guarantor any facts it may now or hereafter know regarding
Debtor, the Collateral, or such other parties; (e) any lack of acceptance or
notice of acceptance of this Guaranty by WorldCom; (f) any lack of
presentment, demand, protest, or notice of demand, protest, dishonor or
nonpayment with respect to any indebtedness or obligations under any of the
WorldCom Documents; (g) any lack of notice of disposition or of manner of
disposition of any Collateral; (h) any lack of other notices to which
Guarantor might otherwise be entitled; (i) failure to properly record any
document or any other lack of due diligence by WorldCom in creating or
perfecting a security interest in or collection, protection, or realization
upon any Collateral or in obtaining reimbursement or performance from any
Person or entity now or hereafter liable for the WorldCom Documents or any
obligation secured thereby; (j) any invalidity, irregularity, or
unenforceability, in whole or in part, of any one or more of the WorldCom
Documents; (k) the inaccuracy of any representation or other provision
contained in any WorldCom Document; (l) any sale or assignment of the
WorldCom Documents, in whole or in part; (m) any sale or assignment by Debtor
of the Collateral, or any portion thereof, whether or not consented to by
WorldCom; (n) any lack of commercial reasonableness in dealing with
Collateral; (o) any deficiencies in the Collateral or any deficiency in the
ability of WorldCom to collect or obtain performance from any Persons or
entities now or hereafter liable for the payment or performance of any
obligation hereby guaranteed; (p) an assertion or claim that the automatic
stay provided by 11 U.S.C. ss. 362 (arising upon the voluntary or involuntarY
bankruptcy proceeding of Debtor), or any other stay provided under any other
Debtor Relief Law (whether statutory, common law, case law, or otherwise) of
any jurisdiction whatsoever, now or hereafter in effect, which may be or
become applicable, shall operate or be interpreted to stay, interdict,
condition, reduce or inhibit the ability

                                     4

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of WorldCom to enforce any of its rights, whether now or hereafter acquired,
which WorldCom may have against Guarantor or the Collateral; (q) any
modifications of the WorldCom Documents or any of the Obligations by
operation of law or by action of any court, whether pursuant to the
Bankruptcy Reform Act of 1978, as amended, or any other Debtor Relief Law
(whether statutory, common law, case law, or otherwise) of any jurisdiction
whatsoever, now or hereafter in effect, or otherwise; (r) notices of any of
the events described in Paragraph 3 hereof and of any other occurrence or
matter with respect to any of the Obligations, this Guaranty, or any of the
other of the WorldCom Documents (s) any right to assert against WorldCom as a
counterclaim, set-off or cross-claim, any counterclaim, set-off, or claim
which it may now or hereafter have against Debtor or other Person liable on
the Obligations; (t) any right to participate in any collateral or any right
benefitting WorldCom in respect of the Obligations; and (u) any right by
which Guarantor might be entitled to require suit on an accrued right of
action in respect of any of the Obligations or require suit against Debtor or
any other Person, whether arising pursuant to any provision of statutory or
case law or otherwise.

         5.   SUBROGATION AND SUBORDINATION.


              (a)  Notwithstanding any reference to subrogation  contained
herein to the contrary, Guarantor hereby irrevocably waives any claim or
other rights which it may have or hereafter acquire against Debtor that arise
from the existence, payment, performance, or enforcement of Guarantor's
obligations under this Guaranty, including, without limitation, any right of
subrogation, reimbursement, exoneration, contribution, indemnification, any
right to participate in any claim or remedy of WorldCom against Debtor, or
any other Person at any time liable for the payment of any or all of the
Obligations, or any Collateral, which WorldCom now has or hereafter acquires,
whether or not such claim, remedy or right arises in equity, or under
contract, statutes or common law, including, without limitation, the right to
take or receive from Debtor, directly or indirectly, in cash or other
property or by set-off or in any other manner, payment or security on account
of such claim or other rights. If any amount shall be paid to Guarantor in
violation of the immediately preceding sentence, such amount shall be deemed
to have been paid to Guarantor for the benefit of, and held in trust for the
benefit of, WorldCom, and shall forthwith be paid to WorldCom to be credited
and applied against the Obligations, whether matured or unmatured, in
accordance with the terms of the Note or the other WorldCom Documents.
Guarantor acknowledges that it will receive direct and indirect benefits from
the financing arrangements contemplated by the Note and the restructuring of
the Debtor's obligations to WorldCom and that the waiver set forth in this
Paragraph 5(a) is knowingly made in contemplation of such benefits.

              (b)  If Guarantor becomes the holder of any indebtedness
payable by Debtor, Guarantor hereby subordinates all indebtedness owing to it
from Debtor to all indebtedness of Debtor to WorldCom and agrees that upon
the occurrence and continuance of a Default or an Event of Default, it shall
not accept any payment on the same until payment in full of the Obligations
of Debtor under the Note, and all other WorldCom Documents and shall in no
circumstance whatsoever attempt to set-off or reduce any obligations
hereunder because of such indebtedness. If any amount shall nevertheless be
paid to Guarantor by Debtor or on behalf of Debtor prior to payment in full
of

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<PAGE>

the Obligations, such amount shall be held in trust for the benefit of
WorldCom and shall forthwith be paid to WorldCom to be credited and applied
to the Obligations, whether matured or unmatured.

         6.   INTENTIONALLY OMITTED.


         7.   COVENANTS. Guarantor covenants and agrees (a) punctually and
properly to perform all of Guarantor's covenants and duties under any other
of the WorldCom Documents; (b) from time to time promptly to furnish WorldCom
with any information or writings which WorldCom may request concerning this
Guaranty; and (c) promptly to notify WorldCom of any claim, action, or
proceeding affecting this Guaranty.

         8.   AMENDMENTS, ETC. No amendment or waiver of any  provision of
this  Guaranty nor consent to any departure by Guarantor therefrom shall in
any event be effective unless the same shall be in writing and signed by
Guarantor and WorldCom, and then such waiver or consent shall be effective
only in the specific instance and for the specific purpose for which given.

         9.  NOTICES. All notices, communications, and materials to be given
or delivered pursuant to this Agreement shall be given or delivered in the
manner provided in, and shall be deemed to be effective in accordance with,
the provisions of the Workout Agreement. For purposes of notices,
communications, and materials to be given or delivered pursuant to this
Agreement, addresses and facsimile numbers and the individuals or departments
to whose attention the same shall be directed are, for WorldCom, as set forth
in the Security Agreement and are, for Guarantor, as follows:

              If to Guarantor:
                               --------------------------

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

                               --------------------------
                               Facsimile No.:
                                             ------------
                               Attention:
                                         ----------------

              with a copy to:  Riordan & McKinzie
                               Twenty-Ninth Floor
                               300 South Grand Avenue
                               Los Angeles, California 90071
                               Attention:  Ronn S. Davids
                               Facsimile No.:  (213) 229-8550

or at such other addresses or facsimile numbers or to the attention of such
other individuals or departments as Guarantor may hereafter specify in a notice
to the other party specifically captioned "Notice of Change of Address."

         10.  NO WAIVER;  REMEDIES.  No failure on the part of WorldCom to
exercise,  and no delay in exercising, any right hereunder or under any of
the WorldCom Documents shall operate as a waiver thereof, nor shall any
single or partial exercise of any right hereunder or under any of the

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WorldCom Documents preclude any other or further exercise thereof or the
exercise of any other right. WorldCom shall not be required to (a) prosecute
collection or seek to enforce or resort to any remedies against Debtor or any
other Person liable on any of the Obligations, (b) join Debtor or any other
Person liable on any of the Obligations in any action in which WorldCom
prosecutes collection or seeks to enforce or resort to any remedies against
Debtor or other Person liable on any of the Obligations, or (c) seek to
enforce or resort to any remedies with respect to any Liens granted to (or
benefitting, directly or indirectly) WorldCom by Debtor or any other Person
liable on any of the Obligations. WorldCom shall not have any obligation to
protect, secure, or insure any of the Collateral or any of the Liens or the
properties or interests in properties subject thereto. The remedies herein
provided are cumulative and not exclusive of any remedies provided by
applicable law.

         11.  RIGHT OF SET OFF. Upon the occurrence and during the
continuance of any Event of Default, WorldCom is hereby authorized at any
time and from time to time, to the fullest extent permitted by law, to set
off and apply any and all deposits (general or special, time or demand,
provisional or final) at any time held and other indebtedness at any time
owing by WorldCom to or for the credit or the account of Guarantor against
any and all of the obligations of Guarantor now or hereafter existing under
this Guaranty, irrespective of whether or not WorldCom shall have made any
demand under this Guaranty. The rights of WorldCom under this Paragraph 11
are in addition to other rights and remedies (including, without limitation,
other rights of set off) which WorldCom or any other WorldCom Entity may have.

         12.  LIENS. Guarantor agrees that WorldCom, in its discretion,
without notice or demand to or upon Guarantor and without affecting either
the liability of Guarantor, Debtor or any other Person liable on any of the
Obligations under, or the Liens and security interests created by, the Note,
or the other WorldCom Documents, or this Guaranty, or any security interest
or other Lien, may foreclose any deed of trust or mortgage or similar Lien
covering interests in real or personal property, and the interests in real or
personal property secured thereby, by nonjudicial sale; and Guarantor hereby
waives any defense to the recovery by WorldCom hereunder against Debtor,
Guarantor, or any collateral of any deficiency after a nonjudicial sale, and
Guarantor expressly waives any defense or benefits that may be derived from
any statute or case law in effect in any jurisdiction. Without limiting the
foregoing, Guarantor waives any defense arising out of any such nonjudicial
sale even though such sale operates to impair or extinguish any right of
reimbursement or subrogation or any other right or remedy of Guarantor
against Debtor or any other Person or any Collateral or any other collateral.
Guarantor hereby agrees that Guarantor shall be liable, subject to the
limitations of Paragraph 2(b) hereof, for any part of the Obligations
remaining unpaid after any foreclosure.

         13.  CONTINUING GUARANTY; TRANSFER OF NOTE. This Guaranty is an
irrevocable continuing guaranty of payment and shall (a) remain in full force
and effect until payment in full of all of the Obligations and all other
amounts payable under this Guaranty, (b) be binding upon Guarantor, its
successors and assigns, and (c) inure to the benefit of and be enforceable by
WorldCom and its successors, transferees, and assigns. Without limiting the
generality of the foregoing clause, (c) WorldCom may assign or otherwise
transfer its rights under the any of the WorldCom Documents or any interest
therein to any other Person, and such other Person shall thereupon become
vested with

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<PAGE>

all the rights or any interest therein, as appropriate, in respect thereof
granted to WorldCom herein or otherwise.

         14.  INFORMATION. Guarantor acknowledges and agrees that it shall
have the sole responsibility for obtaining from Debtor such information
concerning Debtor's financial condition or business operations as Guarantor
may require and that WorldCom has no duty at any time to disclose to
Guarantor any information relating to the business operations or financial
conditions of Debtor.

         15.  GOVERNING LAW; SERVICE OF PROCESS.


              (a)  THIS  GUARANTY SHALL BE DEEMED A CONTRACT MADE UNDER THE
LAWS OF THE STATE OF OKLAHOMA AND SHALL BE CONSTRUED AND ENFORCED IN
ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF OKLAHOMA, EXCEPT TO
THE EXTENT THAT FEDERAL LAWS MAY GOVERN THE VALIDITY, CONSTRUCTION,
ENFORCEMENT, AND INTERPRETATION OF ALL OR ANY PART OF THIS GUARANTY.
GUARANTOR AGREES THAT THE FEDERAL AND STATE COURTS LOCATED IN TULSA COUNTY,
OKLAHOMA, WILL HAVE JURISDICTION OVER ALL PROCEEDINGS IN CONNECTION HEREWITH.

              (b)  GUARANTOR HEREBY WAIVES PERSONAL SERVICE OF ANY LEGAL
PROCESS UPON IT. IN ADDITION, GUARANTOR AGREES THAT SERVICE OF PROCESS MAY BE
MADE UPON IT BY REGISTERED MAIL (RETURN RECEIPT REQUESTED) DIRECTED TO
GUARANTOR AT ITS ADDRESS DESIGNATED FOR NOTICE UNDER THIS GUARANTY AND THAT
SERVICE SO MADE SHALL BE DEEMED TO BE COMPLETED UPON RECEIPT BY GUARANTOR.
NOTHING IN THIS PARAGRAPH 15 SHALL AFFECT THE RIGHT OF LENDER TO SERVE LEGAL
PROCESS IN ANY OTHER MANNER PERMITTED BY LAW.

         16.  WAIVER OF JURY TRIAL. TO THE MAXIMUM EXTENT PERMITTED BY LAW,
GUARANTOR AND WORLDCOM HEREBY WAIVE ANY RIGHT THAT EITHER MAY HAVE TO A TRIAL
BY JURY OF ANY DISPUTE (WHETHER A CLAIM IN TORT, CONTRACT, EQUITY, OR
OTHERWISE) ARISING UNDER OR RELATING TO THIS GUARANTY, THE OTHER WORLDCOM
DOCUMENTS, OR ANY RELATED MATTERS AND AGREE THAT ANY SUCH DISPUTE SHALL BE
TRIED BEFORE A JUDGE SITTING WITHOUT A JURY.

         17.  WAIVER OF RIGHTS. Guarantor hereby waives and renounces, to the
fullest extent permitted by law, all rights to the benefits of any statute of
limitations and any moratorium, reinstatement, marshaling, forbearance,
valuation, stay, extension, redemption, appraisement, exemption and homestead
law or principle of law now or hereafter provided by the Constitution and
laws of the United States of America and of each state thereof, both as to
itself and in and to all of

                                    8
<PAGE>

its property, real and personal, against the enforcement and collection of
the Obligations evidenced by this Guaranty.

         18.  LIMIT OF VALIDITY. If from any circumstances whatsoever
fulfillment of any provisions of this Guaranty, at the time performance of
such provision shall be due, shall involve transcending the limit of validity
presently prescribed by any applicable usury statute or any other applicable
law, with regard to obligations of like character and amount, then IPSO FACTO
the obligation to be fulfilled shall be reduced to the limit of such
validity, so that in no event shall any exaction be possible under this
Guaranty that is in excess of the current limit of such validity, but such
obligation shall be fulfilled to the limit of such validity. The provisions
of this section shall control every other provision of this Guaranty.

         19.  GUARANTOR INSOLVENCY. Should Guarantor become insolvent, fail
to pay its debts generally as they become due, voluntarily seek, consent to,
or acquiesce in the benefits of any Debtor Relief Laws, or become a party to
or be made the subject of any proceeding provided for by any Debtor Relief
Laws (other than as a creditor or claimant) that could suspend or otherwise
adversely affect the rights of WorldCom granted hereunder, then the
obligations of Guarantor under this Guaranty shall be, as between Guarantor
and WorldCom, fully matured, due, and payable obligations of Guarantor to
WorldCom (without regard to whether Debtor is then in default under any of
the WorldCom Documents or whether any of the Obligations may then be due and
owing by Debtor to WorldCom), payable in full by Guarantor to WorldCom upon
demand, which shall be the estimated amount owing in respect of the
contingent claim created hereunder.

         20.  ENTIRE AGREEMENT. THIS GUARANTY REPRESENTS THE FINAL AGREEMENT
BETWEEN GUARANTOR AND WORLDCOM REGARDING THE GUARANTYING OF THE OBLIGATIONS
AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR
SUBSEQUENT ORAL  AGREEMENTS WITH RESPECT  THERETO. GUARANTOR ACKNOWLEDGES
THAT THERE ARE NO CONTEMPORANEOUS ORAL AGREEMENTS WITH RESPECT TO THE SUBJECT
MATTER HEREOF.

         21.  MISCELLANEOUS. Time is of the essence with respect to all
obligations of Guarantor hereunder. This Guaranty shall in no event be
impaired by any change which may arise by reason of the dissolution of Debtor
or Guarantor. Guarantor expressly waives notice of transfer or assignment of
this Guaranty and acknowledges that the failure by WorldCom to give any such
notice shall not affect the liabilities of Guarantor hereunder.
Notwithstanding the foregoing, Guarantor shall not assign any of its rights
or obligations under this Guaranty. All personal pronouns used herein,
whether used in the masculine, feminine, or neuter gender, shall include all
other genders; and the singular shall include the plural and vice versa.
Titles of articles and sections are for convenience only and in no way
define, limit, amplify, or describe the scope or intent of any provisions
hereof. If Guarantor is a partnership, all of the provisions hereof referring
to Guarantor shall be construed to apply to each of the general partners of
Guarantor and of any and all further tiers of general partners in the
structure of Guarantor.

                                     9.

<PAGE>

              IN WITNESS WHEREOF, Guarantor has caused this Guaranty to be
duly executed and delivered by its respective officers thereunto duly authorized
as of the date first above written.

                                       GUARANTOR:



                                       BY:
                                          ---------------------------

                                           By:
                                              -----------------------
                                           Its:
                                               ----------------------

                                       Attest:
                                               -----------------------

                                               Name:
                                                    ------------------
                                               Title:
                                                     -----------------

                                       (CORPORATE SEAL)


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