<PAGE>

                                                                  Exhibit 10.1.6
                                                               Loan No. ML0883T1


                              CONTINUING GUARANTY


       THIS CONTINUING GUARANTY (this "Guaranty") is made as of June 29, 2001,
by ITC GLOBE, INC. ("Guarantor"), for the benefit of the COBANK, ACB ("CoBank").

                                R E C I T A L S:

       WHEREAS, Globe Telecommunications, Inc. ("Globe") owns 100% of the issued
and outstanding capital and voting stock in the Guarantor; and

       WHEREAS, CoBank and Valley Telephone Company, Inc., Interstate Telephone
Company, Inc, and Globe (collectively, the "Borrowers") have entered into that
certain Master Loan Agreement, dated as of even date herewith (the "MLA") and
that certain First Supplement to the Master Loan Agreement, dated as of even
date herewith, (the "First Supplement"; the MLA and the First Supplement, as
either may be amended, supplemented, modified, extended or restated from time to
time, collectively, the "Loan Agreement"); and

       WHEREAS, as an inducement to CoBank to enter into the Loan Agreement and
make the advances provided for therein, Guarantor has agreed to guarantee the
obligations of the Borrowers under the Loan Agreement, all on the terms and
conditions set forth in this Guaranty;

       NOW, THEREFORE, in consideration of the foregoing, and intending to be
legally bound hereby, Guarantor hereby agrees as follows:

       SECTION 1.  Rules of Construction.  The following rules of construction
shall be applicable for all purposes of this Guaranty and all amendments and
supplements hereto except as otherwise expressly provided or unless the context
otherwise requires:

       (a)  The terms used herein shall include the plural as well as the
singular, and vice versa.

       (b)  All references in this Guaranty to designated sections, paragraphs
and other subdivisions are to the designated sections, paragraphs and
subdivisions of this Guaranty.

      (c)  The terms "herein," "hereof" and "hereunder" and similar words refer
to this Guaranty as a whole and not to any particular section, paragraph or
subdivision.

      (d)  The term "person" includes any individual, corporation, limited
liability company, partnership, joint venture, association, trust, sole
proprietorship, unincorporated organization and any government authority or any
agency or political subdivision thereof.
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Continuing Guaranty/ITC Globe Inc.
Loan No. ML0883T1


      (e)  The terms "include," "including" and similar terms shall be
construed as if followed by the phrase "without being limited to."

      (f)  Capitalized terms used in this Guaranty, unless otherwise defined
herein, shall have the meanings assigned to them in the Loan Agreement.

      SECTION 2.  Obligations.  "Obligations" shall mean the payment and
performance of all obligations of the Borrowers, whether now existing or
hereafter arising, under the Loan Agreement and all other Loan Documents to
which any Borrower is a party, including, without limitation, that certain
Promissory Note, dated of even date herewith, made by the Borrowers to CoBank in
the principal face amount of $40,000,000 (such Promissory Note and all
amendments, modifications, extensions, renewals and replacements thereof, the
"Note").

      SECTION 3.  Guaranty Provisions.

      (a)  In consideration of loans, advances or disbursements heretofore or
hereafter granted by CoBank to the Borrowers pursuant to the Loan Agreement or
otherwise and for other good and valuable consideration, the adequacy,
sufficiency and receipt of which are hereby acknowledged, Guarantor hereby
absolutely, unconditionally, irrevocably, completely and immediately guarantees
the prompt payment of, when due, whether by acceleration or otherwise, and the
prompt payment and performance of the Obligations. The liability of Guarantor
hereunder shall not be reduced as a result of amounts collected pursuant to any
other guaranty, but shall be determined with reference to the amount of
Obligations prior to collection from any party other than the Borrowers;

      (b)  Guarantor further agrees to pay to CoBank, upon demand, (i) all
losses and reasonable costs and expenses, including, without limitation,
reasonable attorneys' fees and expenses, incurred in attempting to cause the
Obligations to be paid, performed or otherwise satisfied or in attempting to
protect or preserve any property, personal or real, securing the Obligations and
(ii) all losses and reasonable costs and expenses, including, without
limitation, reasonable attorneys' fees and expenses, incurred in enforcing or
endeavoring to enforce this Guaranty and any other Loan Document to which
Guarantor is a party or in attempting to protect or preserve property pledged
under any Loan Document to which Guarantor is a party;

      (c)  Guarantor expressly guarantees, within its maximum liability
hereunder, any sum or sums which become due and owing to CoBank as a result of
any order of a bankruptcy court which requires CoBank to turn over moneys paid
by the Borrowers, Guarantor or any other person to CoBank on account of the
Obligations;

      (d)  Guarantor assents to all terms and agreements heretofore or hereafter
made by the Borrowers, any of their subsidiaries or any other guarantor of the
Borrowers with CoBank;

      (e)  Guarantor hereby consents to the following and agrees that its
liability will not be affected or impaired by (i) the exchange, release or
surrender of any collateral to the

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Continuing Guaranty/ITC Globe Inc.
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Borrowers or any other person, including any other guarantor, pledgor or
grantor, or the waiver, release or subordination of any security interest, in
whole or in part; (ii) the waiver or delay in the exercise of any of CoBank's
rights or remedies against the Borrowers or any other person, including any
other guarantor; (iii) the release of the Borrowers or any other person,
including any other person guaranteeing any portion of the Obligations; (iv) the
renewal, extension or modification of the terms of any of the Obligations or any
instrument or agreement evidencing the same;

      (f)  Guarantor waives acceptance hereof, notice of acceptance hereof, and
notice of acceleration of and intention to accelerate the Obligations, and
waives presentment, demand, protest, notice of dishonor, notice of default,
notice of nonpayment or protest in relation to any instrument evidencing any of
the Obligations, and any other demands and notices required by law except as
such waiver may be expressly prohibited by law;

      (g)  This is a guaranty of payment and performance and not of collection.
The liability of Guarantor under this Guaranty shall be absolute, unconditional,
direct, complete and immediate and shall not be contingent upon the pursuit of
any remedies against the Borrowers or any other guarantor or person, nor against
any security or lien available to CoBank, its successors, successors-in-title,
endorsees or assigns. Guarantor waives any right to require that an action be
brought against the Borrowers or any other person or to require that resort be
had to any security. In the event of a default under the Loan Documents, or any
of them, CoBank shall have the right to enforce its rights, powers and remedies
under any of the Loan Documents, in any order, and all rights, powers and
remedies available to CoBank in such event shall be nonexclusive and cumulative
of all other rights, powers and remedies provided thereunder or hereunder or by
law or in equity. Accordingly, Guarantor hereby authorizes and empowers CoBank
upon acceleration of the maturity of the Note or any other Obligation, at its
sole discretion, and without notice to Guarantor, to exercise any right or
remedy which CoBank may have or any right or remedy hereinafter granted which
CoBank may have as to any security. Guarantor expressly waives any right to
require any action on the part of CoBank to proceed to collect amounts due under
the Note or any other Obligation;

      (h)  Until the Obligations are paid in full, Guarantor hereby subordinates
any and all indebtedness of any Borrower now or hereafter owed to Guarantor to
all obligations of the Borrowers to CoBank, and agrees with CoBank that, from
and after the occurrence of a default or event of default under any of the Loan
Documents and for so long as such default or event of default exists, Guarantor
shall not demand or accept any payment of principal or interest from the
Borrowers shall not claim any offset or other reduction of Guarantor's liability
hereunder because of any such indebtedness and shall not take any action to
obtain any of the security for the Obligations; provided, however, that, if
                                                --------  -------
CoBank so requests, such indebtedness shall be collected, enforced and received
by Guarantor as trustee for CoBank and be paid over to CoBank on account of the
Obligations of the Borrowers to CoBank, but without reducing or affecting in any
manner the liability of Guarantor under the other provisions of this Guaranty;

      (i)  Guarantor hereby authorizes CoBank, without notice to Guarantor, to
apply all payments and credits received from the Borrowers or from any guarantor
or realized from any

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Continuing Guaranty/ITC Globe Inc.
Loan No. ML0883T1


security in such manner and in such priority as CoBank in its sole judgment
shall see fit to the Obligations which are the subject of this Guaranty;

      (j)  The liability of Guarantor under this Guaranty shall not in any
manner be affected by reason of any action taken or not taken by CoBank, which
action or inaction is consented and agreed to by Guarantor, nor by the partial
or complete unenforceability or invalidity of any other guaranty or surety
agreement, pledge, assignment, or other security for any of the Obligations. No
delay in making demand on Guarantor for satisfaction of its liability hereunder
shall prejudice CoBank's right to enforce such satisfaction. All of CoBank's
rights and remedies shall be cumulative and any failure of CoBank to exercise
any right hereunder shall not be construed as a waiver of the right to exercise
the same or any other right at any time, and from time to time, thereafter;

      (k)  This Guaranty shall be a continuing one and shall be binding upon
Guarantor regardless of how long before or after the date hereof the Obligations
are incurred. This Guaranty shall remain in full force and effect until a
written instrument of termination shall be executed and delivered by a duly
authorized officer of CoBank. CoBank will only be obligated to execute such an
instrument of termination if: (i) all Obligations have been paid in full and
(ii) CoBank has no further commitment or obligation to extend credit to the
Borrowers. If so terminated, this Guaranty and Guarantor's obligations hereunder
shall be automatically reinstated if at any time payment in whole or in part of
any of the Obligations is rescinded or restored to the Borrowers or other payor,
or must be paid to any other person, upon the insolvency, bankruptcy,
liquidation, dissolution or reorganization of the Borrowers or other payor, all
as though such payment has not been made; and

      (l)  Until the Obligations are paid finally and in full, or this Guaranty
is released as provided herein, Guarantor hereby irrevocably waives any and all
rights it may have to enforce any of CoBank's rights or remedies or participate
in any security now or hereafter held by CoBank, and any and all such other
rights of subrogation, reimbursement, contribution or indemnification against
the Borrowers or any other person having any manner of liability for the
Borrowers' obligations to CoBank, whether or not arising hereunder, by
agreement, at law or in equity.

      SECTION 4.  Representations and Warranties.  Guarantor represents and
warrants to CoBank, on the date hereof and on the date any advance under the
Loan Agreement is made, as follows:

      (a)  Organization, Powers, Existence, Etc.  Guarantor (i) is duly
           -------------------------------------
organized, validly existing, and in good standing under the laws of its state of
incorporation or organization (as applicable); (ii) is duly qualified to do
business and is in good standing in each jurisdiction in which the transaction
of its business makes such qualification necessary; (iii) has all requisite
corporate, limited liability company or partnership (as applicable) and legal
power to own and operate its assets and to carry on its business and to enter
into and perform its obligations under the Loan Documents to which it is a
party; and (iv) has duly and lawfully obtained and

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Continuing Guaranty/ITC Globe Inc.
Loan No. ML0883T1

maintained all licenses, certificates, permits, authorizations, approvals, and
the like which are material to the conduct of its business or which may be
otherwise required by law.

      (b)  Due Authorization; No Violations; Etc.  The execution and delivery by
           --------------------------------------
Guarantor of, and the performance by Guarantor of its obligations under, the
Loan Documents to which it is a party have been duly authorized by all requisite
corporate, limited liability company or partnership (as applicable) action on
the part of Guarantor and do not and will not (i) violate any provision of any
law, rule or regulation, any judgment, order or ruling of any court or
governmental agency, the articles of incorporation or organization (as
applicable) or bylaws, operating agreement or partnership agreement (as
applicable) of Guarantor, or any agreement, indenture, mortgage, or other
instrument to which Guarantor is a party or by which Guarantor or any of its
properties is bound or (ii) be in conflict with, result in a breach of, or
constitute with the giving of notice or lapse of time, or both, a default under
any such agreement, indenture, mortgage, or other instrument. No action on the
part of any shareholder, member or partner (as applicable) of Guarantor is
necessary in connection with the execution and delivery by Guarantor of, and the
performance by Guarantor of its obligations under, the Loan Documents to which
it is a party.

      (c)  Governmental Approval.  No consent, permission, authorization, order,
           ----------------------
or license of any governmental authority is necessary in connection with the
execution, delivery, performance, or enforcement of the Loan Documents to which
Guarantor is a party, except such as have been obtained and are in full force
and effect.

      (d)  Binding Agreement.  Each of the Loan Documents to which Guarantor is
           ------------------
a party is, or when executed and delivered will be, the legal, valid, and
binding obligation of Guarantor, enforceable in accordance with its terms,
subject only to limitations on enforceability imposed by applicable bankruptcy,
insolvency, reorganization, moratorium, or similar laws affecting creditors'
rights generally.

      (e)  Compliance with Laws.  Guarantor is in compliance in all material
           ---------------------
respects with all federal, state, and local laws, rules, regulations,
ordinances, codes, and orders (collectively, "Laws"), the failure to comply with
which could have a material adverse effect on the condition, financial or
otherwise, operations, properties, or business of Guarantor, or on the ability
of Guarantor to perform its obligations under the Loan Documents to which it is
a party.

      (f)  Environmental Compliance.  Without limiting the provisions of
           -------------------------
Subsection (e) above, all property owned or leased by Guarantor and all
operations conducted by it are in compliance in all material respects with all
Laws relating to environmental protection, the failure to comply with which
could have a material adverse effect on the condition, financial or otherwise,
operations, properties, or business of Guarantor, or on the ability of Guarantor
to perform its obligations under the Loan Documents to which it is a party.

      (g)  Litigation.  There are no pending legal, arbitration, or governmental
           -----------
actions or proceedings to which Guarantor is a party or to which any of its
property is subject which, if adversely determined, could have a material
adverse effect on the condition, financial or

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Continuing Guaranty/ITC Globe Inc.
Loan No. ML0883T1

otherwise, operations, properties, or business of Guarantor, or on the ability
of Guarantor to perform its obligations under the Loan Documents to which it is
a party, and to the best of Guarantor's knowledge, no such actions or
proceedings are threatened or contemplated.

      (h)  Financial Statements; No Material Adverse Change; Etc.  All financial
           ------------------------------------------------------
statements submitted to CoBank in connection with loans made or to be made
pursuant to the Loan Agreement or otherwise in connection with this Guaranty
fairly and fully present the financial condition of Guarantor and the results of
Guarantor's operations for the periods covered thereby, and are prepared in
accordance with GAAP consistently applied. Since the dates thereof, there has
been no material adverse change in the financial condition or operations of
Guarantor. All budgets, projections, feasibility studies, and other
documentation regarding Guarantor submitted to CoBank were based upon
assumptions that were reasonable and realistic at the time submitted, and as of
the date hereof, no fact has come to light, and no event or transaction has
occurred, which would cause any assumption made therein not to be reasonable or
realistic, other than as disclosed in writing to CoBank.

      (i)  Principal Place of Business.  The principal place of business and
           ----------------------------
chief executive office of Guarantor is at the address of Guarantor shown in
Section 8(e) hereof.

      (j)  Employee Benefit Plans.  Guarantor is in compliance in all material
           -----------------------
respects with the applicable provisions of the Employee Retirement Income
Security Act of 1974, as amended, and the regulations and published
interpretations thereunder.

      (k)  Taxes.  Guarantor has filed or caused to be filed, all federal,
           ------
state and local tax returns that are required to be filed, and has paid all
taxes as shown on said returns or on any assessment received by Guarantor to the
extent that such taxes have become due.

      (l)  Financial Condition.  Guarantor represents and warrants that the
           --------------------
liability and obligations of Guarantor incurred or arising under this Guaranty,
and of the Borrowers incurred or arising under the Loan Agreement may reasonably
be expected to benefit substantially Guarantor directly or indirectly, and
Guarantor's board of directors has made that determination. Guarantor represents
and warrants that it has full and complete access to all of the Loan Documents
and other documents relating to the Obligations, has reviewed them and is fully
aware of the meaning and effect of their contents. Guarantor is fully informed
of all circumstances that bear upon the risks of executing this Guaranty which a
diligent inquiry would reveal. Guarantor agrees that CoBank will have no
obligation to advise or notify Guarantor of or provide Guarantor with any data
or information.

      SECTION 5.  Events of Default.  The occurrence of any of the following
shall constitute an "Event of Default" hereunder:

      (a)  Representations and Warranties.  Any representation or warranty made
           ------------------------------
by Guarantor herein or in any Loan Document to which it is a party shall prove
to have been false or misleading in any material respect on or as of the date
made or deemed made.

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Continuing Guaranty/ITC Globe Inc.
Loan No. ML0883T1

      (b)  Covenants and Agreements.  Guarantor should fail to perform or
           ------------------------
comply with any covenant or agreement contained herein.

      (c)  Cross-Default.  The occurrence of an Event of Default under, or the
           -------------
failure, after any applicable grace period, on the part of the Borrowers,
Guarantor or any other party (other than CoBank) to observe, keep or perform any
covenant or agreement contained in any Loan Document other than this Guaranty.

      SECTION 6.  Security.  Guarantor shall execute and deliver, on the date
hereof, in form and substance satisfactory to CoBank that certain Security
Agreement, made by and between Guarantor and CoBank, as the same may be amended,
supplemented, modified, extended or restated from time to time, pursuant to
which Guarantor has granted CoBank a first-priority lien, security interest and
security title in substantially all of Guarantor's now-owned and hereafter-
acquired personal property.

      SECTION 7.  Miscellaneous.

      (a)  Governing Law.  Except to the extent governed by applicable federal
           -------------
law, this Guaranty shall be governed by and construed in accordance with the
laws of the State of Colorado without reference to choice of law doctrine.

      (b)  Binding Effect.  This Guaranty shall inure to the benefit of and be
          --------------
binding upon the parties hereto and their respective successors and assigns,
including any holder or owner of the Notes or the other Loan Documents.

      (c)  Severability.  If any one or more of the provisions contained herein
           ------------
shall for any reason be held to be invalid, illegal or unenforceable in any
respect, such invalidity, illegality or unenforceability shall not affect any
other provisions of this Guaranty, but this Guaranty shall be construed as if
such invalid, illegal or unenforceable provisions had not been contained herein.

      (d)  Non-Waiver; Modification; Election of Remedies.  The failure of any
           ----------------------------------------------
party to insist, in any one or more instances, upon a strict performance of any
of the terms and conditions of this Guaranty, or to exercise or fail to exercise
any option or right contained herein, shall not be construed as a waiver or a
relinquishment for the future of such right or option, but the same shall
continue and remain in full force and effect. The continued performance by any
party of this Guaranty with knowledge of the breach of any term or condition
hereof shall not be deemed a waiver of such breach, and no waiver by any party
of any provision hereof shall be deemed to have been made, or operate as an
estoppel, unless expressed in writing and signed by such party. No enforcement
of any remedy shall constitute an election of remedies.

      (e)  Notices.  All notices hereunder shall be delivered as provided in
           -------
Section 14 of the MLA and to the Guarantor at the address set forth therein for
the Borrowers (or such other address as shall be specified by like notice).

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Continuing Guaranty/ITC Globe Inc.
Loan No. ML0883T1

      SECTION 8.  Consent to Jurisdiction.  Guarantor agrees that any legal
action or proceeding with respect to this Guaranty or any other Loan Document
may be brought in the courts of the State of Colorado, or of the United States
of America for the District of Colorado, all as CoBank may elect.  By execution
of this Guaranty, Guarantor hereby irrevocably submits to each such
jurisdiction, expressly waiving any objection it may have to the laying of venue
by reason of its present or future domicile.  Nothing contained herein shall
affect the right of CoBank to commence legal proceedings or otherwise proceed
against Guarantor in any other jurisdiction or to serve process in any manner
permitted or required by law.

      SECTION 9.  Waiver of Jury Trial.  GUARANTOR AND COBANK HEREBY WAIVE THEIR
RESPECTIVE RIGHTS TO A JURY TRIAL OF ANY CLAIM OR CAUSE OF ACTION BASED UPON OR
ARISING OUT OF THIS GUARANTY, ANY OTHER LOAN DOCUMENT, OR ANY DEALINGS BETWEEN
THEM RELATING TO THE SUBJECT MATTER OF THIS GUARANTY, AND THE SURETY
RELATIONSHIP THAT IS BEING ESTABLISHED.  THE SCOPE OF THIS WAIVER IS INTENDED TO
BE ALL ENCOMPASSING OF ANY AND ALL DISPUTES THAT MAY BE FILED IN ANY COURT AND
THAT RELATE TO THE SUBJECT MATTER OF THIS GUARANTY, INCLUDING WITHOUT
LIMITATION, CONTRACT CLAIMS, TORT CLAIMS, BREACH OF DUTY CLAIMS, AND ALL OTHER
COMMON LAW AND STATUTORY CLAIMS.  GUARANTOR AND COBANK ACKNOWLEDGE THAT THIS
WAIVER IS A MATERIAL INDUCEMENT TO ENTER INTO A BUSINESS RELATIONSHIP, THAT EACH
HAS ALREADY RELIED ON THE WAIVER IN ENTERING INTO THIS GUARANTY AND THAT EACH
WILL CONTINUE TO RELY ON THE WAIVER IN THEIR RELATED FUTURE DEALINGS.  GUARANTOR
AND COBANK FURTHER WARRANT AND REPRESENT THAT EACH HAS REVIEWED THIS WAIVER WITH
ITS LEGAL COUNSEL, AND THAT EACH KNOWINGLY AND VOLUNTARILY WAIVES ITS JURY TRIAL
RIGHTS FOLLOWING CONSULTATION WITH LEGAL COUNSEL.  THIS WAIVER IS IRREVOCABLE,
MEANING THAT IT MAY NOT BE MODIFIED EITHER ORALLY OR IN WRITING, AND THE WAIVER
SHALL APPLY TO ANY SUBSEQUENT AMENDMENTS, RENEWALS, SUPPLEMENTS OR MODIFICATIONS
TO THE LOAN DOCUMENTS, OR TO ANY OTHER DOCUMENTS OR AGREEMENTS RELATING TO THE
LOAN.  IN THE EVENT OF LITIGATION, THIS GUARANTY, MAY BE FILED AS A WRITTEN
CONSENT TO A TRIAL BY THE COURT.  GUARANTOR AND COBANK ALSO WAIVE ANY BOND OR
SURETY OR SECURITY UPON SUCH BOND WHICH MIGHT, BUT FOR THIS WAIVER, BE REQUIRED
OF COBANK.


                     [Signatures appear on following page]

                                       8
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Continuing Guaranty/ITC Globe Inc.
Loan No. ML0883T1

       IN WITNESS WHEREOF, Guarantor, intending to be legally bound hereby, has
caused this Guaranty to be executed and delivered and attested under seal by its
duly authorized officers as of the day and year first above written.


                                 ITC GLOBE, INC.


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


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

                                           [CORPORATE SEAL]