Document:

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                                                                    EXHIBIT 10.1

                                 COLLATERAL NOTE
                       (hereinafter the 'Collateral Note")

<TABLE>
<S>                                                <C>
Borrowers: Sonus Communication Holdings, Inc.      Lender:  Citizens Telecommunications Company
           1600 Wilson Boulevard, Suite 1008                3 High Ridge Park
           Arlington, VA  22209                             Stamford, CT 06905
and
           Empire One Telecommunications, Inc.
           254 West 31st Street
           New York, NY 10001

Principal Amount: $358,461.88         Interest Rate: 10.5%      Date of Collateral Note:
                                                                March 29, 2000
</TABLE>

       For value received, the undersigned, SONUS COMMUNICATION HOLDINGS, INC.
jointly and severally with its wholly owned subsidiary, EMPIRE ONE
TELECOMMUNICATIONS, INC. ("Borrowers") both Delaware corporations, promise to
pay to CITIZENS TELECOMMUNICATIONS COMPANY, ("Lender") or order, the principal
amount of Three Hundred Fifty Eight Thousand Four Hundred Sixty One and 88/100
Dollars ($358,461.88), together with interest thereon. Said sum shall be paid in
the following manner:

Borrowers will pay this Collateral Note in eleven (11) payments as follows: one
irregular payment of Nineteen Thousand Eight Hundred and Eighty Three Dollars
and Eight Four Cents (19,883.84) on April 1, 2000, nine regular payments of
Thirteen Thousand Eight Hundred Ten and 98/100 Dollars ($13,810.98) each and one
irregular last payment of Two Hundred Thirty-Five Thousand Seven Hundred
Sixty-Eight and 77/100 Dollars ($229,695.83). Borrower's first payment is due
April 1, 2000, and all subsequent payments are due on the first day of each
month thereafter until the full amount of the principal and interest is paid.
Borrower's final payment due March 1, 2001, will be for all principal and
accrued interest not yet paid. Payments include principal and interest. Interest
on this Collateral Note is computed on a 360 day year simple interest basis;
that is, by applying the ratio of the annual interest rate over a year of 360
days, multiplied by the outstanding principal balance, multiplied by the actual
number of days the principal balance is outstanding using a 360 day year. Unless
otherwise agreed or required by applicable law, payments will be applied first
to accrued unpaid interest, then to principal, and any remaining amount to any
unpaid collection costs and late charges. A schedule of principal and interest
payments is attached hereto as Attachment 3.

Conditions Precedent to Release of Proceeds by Lender

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(a) Lender shall have received evidence that this Collateral Note, the Security
Agreement, and the Stock Pledge and Escrow Agreement have been duly authorized,
executed, and delivered by Borrower to Lender; and

(b) All guaranties required by Lender for the Loan shall have been executed by
each guarantor listed below, delivered to Lender, and be in full force and
effect. The guarantors are:

<TABLE>
<CAPTION>
      Guarantor                                         Title
      ---------                                         -----

<S>                                 <C>
JOHN K. FRIEDMAN                    COO of SONUS Communication Holdings, Inc and
                                    CEO of Empire One Telecommunications, Inc.
W. TODD COFFIN                      CEO of SONUS Communication Holdings, Inc.
</TABLE>

SECURITY. Borrowers have granted Lender a security interest, to secure the
payment of this note, in the following property: all of the undersigned
corporations' now owned and hereafter acquired accounts, including, but not
limited to, accounts receivable and contract rights, client base list, chattel
paper, documents and instruments and the right to receive payment under them.

        Every maker, endorser, and guarantor of this Collateral Note, or the
obligation represented by it, waives, in the event of default, presentment,
demand, notice, protest, and all other demands and notices in connection with
the delivery, acceptance, performance, or enforcement of this Collateral Note,
assents to any extension or postponement of the time of payment or any other
indulgence, to any substitution, exchange or release of collateral, and/or to
the addition or the release of any other party or persons primarily or
secondarily liable. Lender agrees to grant a cure period of ten (10) business
days after written notice of default has been given to the undersigned
corporation. Subject to this opportunity to cure, this Collateral Note will
automatically accelerate in the event of default and all amounts will become
immediately due and payable.

This Collateral Note dated March 29, 2000 replaces the Collateral Note dated
April 4, 1997 by and between Empire One Telecommunications, Inc. (a predecessor
New York corporation) and Citizens Telecommunications Company. Upon the
execution of this note by the Parties hereto, the Collateral Note dated April 4,
1997 will be considered satisfied.

       The undersigned will pay (i) on demand all costs of collection and (ii)
reasonable attorneys' fees, incurred or paid by the holder in enforcing this
Collateral Note on default. As herein used, the word "holder" shall mean the
payee or other endorsee of

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this Collateral Note, who is in possession of it, or the bearer of it, if this
Collateral Note is at the time payable to the bearer.

                                       SONUS COMMUNICATION HOLDINGS, INC.

                                       By: /s/ W. Todd Coffin
                                          --------------------------------------
                                                   W. Todd Coffin
                                                   Chief Executive Officer

                                       EMPIRE ONE TELECOMMUNICATIONS, INC.

                                       By: /s/ John K. Friedman
                                          --------------------------------------
                                                   John K. Friedman
                                                   Chief Executive Officer

                                       3<PAGE>   1
                                                                    EXHIBIT 10.2

                               SECURITY AGREEMENT
                     (hereinafter the "Security Agreement")

Dated:     March 29, 2000

                                   Section One
                           Promise to Pay; Collateral
                               Security Agreement

        Sonus Communication Holdings, Inc. a Delaware corporation located at
1600 Wilson Boulevard, Suite 1008, Arlington, Virginia 22209, jointly and
severally with Empire One Telecommunications, Inc., a Delaware corporation,
located at 254 West 31st Street, New York, New York 10001 ("Borrowers"), have
delivered that certain Collateral Note of even date herewith ("Collateral
Note") to Citizens Telecommunications Company ("Secured Party"), in the
principal amount of Three Hundred Fifty Eight Thousand Four Hundred Sixty One
and 88/100 Dollars ($358,461.88), payable as follows:

        In order to secure payment of the Collateral Note, Borrowers hereby
grant to Secured Party a security interest in the following collateral: all of
Sonus Communication Holdings, Inc. and Empire One Telecommunications, Inc.'s
now owned and hereafter acquired accounts, including, but not limited to,
accounts receivable and contract rights, client base list, chattel paper,
documents and instruments and the right to receive payment under them (the
"Collateral").

                                   Section Two
                                Events of Default

        At the option of the Secured Party, all obligations shall become
immediately due and payable upon the occurrence of any of the following events
of default and the expiration of the applicable cure period:

        (a) Default in the payment or performance of any payment liability or
payment obligation of any of the undersigned, or of any maker, endorser, or
guarantor of any liability or obligation of any of the undersigned to the
Secured Party;

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        (b) Death, dissolution, termination of existence, insolvency, business
failure, appointment of a receiver of any part of the property of, assignment
for the benefit of creditors by, or the commencement of any proceedings under
any bankruptcy or insolvency laws by or against, any maker, endorser, or
guarantor of the Collateral Note (except for the filing of any involuntary
petition under bankruptcy laws that is set aside or withdrawn or ceases to be
in effect within thirty (30) days of such filing);

        (c) Any representation or warranty or any other statement of a material
fact herein or in any writing, certificate, report, or statement at any time
furnished to Secured Party pursuant to or in connection with this Security
Agreement, or otherwise, is false or misleading in any material respect.

        Secured Party agrees to grant a cure period of ten (10) business days
after written notice of default has been given to the undersigned corporation.
A notice of default shall be deemed delivered if mailed by registered or
certified mail or sent by courier or express service guaranteeing overnight
delivery to the Borrowers and the Guarantors at the addresses first above given
or such other address as the Borrowers and Guarantors may from time to time
designate in writing.

                                  Section Three
                               Remedies on Default

        Upon the occurrence of any such events of default, which have not been
cured within the applicable cure period, and at any later time, the Secured
Party shall have the following remedies:

        (a) The Secured Party may, (subject to the provisions of the Stock
Pledge and Escrow Agreement of even date herewith, a copy of which is attached
hereto as Exhibit A) at its option, transfer at any time to itself or to its
nominee any securities pledged as collateral, and receive the income from such
securities, and hold the income as security, or apply it on the principal or
interest due under the Collateral Note;

        (b) any deposits or other sums any time credited by or due from the
Secured Party to any maker, endorser, or guarantor of the Collateral Note, and
any securities or other property of any maker, endorser, or guarantor in
possession of the Secured Party, may at all times be held and treated as
collateral security for the payment of the obligations. The Secured Party shall
apply or set off such deposits or other sums against the obligations at any
time in the case of makers, but only with respect to matured liabilities in the
case of endorsers or guarantors;

        (c) the Secured Party may at its option, demand, sue for, collect, or
make any compromise or settlement it deems desirable with reference to
collateral held;

        (d) all the remedies of a secured party under the New York Uniform
Commercial Code.

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                                  Section Four
                                 Notice of Sale

        Unless the collateral is perishable or threatens to decline speedily in
value or is of a type customarily sold on a recognized market, the Secured Party
will give the undersigned reasonable notice of the time and place of any public
sale of such collateral, or of the time after which any private sale or other
intended disposition is to be made. The requirement of reasonable notice shall
be met if such notice is mailed, postage prepaid, to the undersigned at the
address given below at least twenty (20) calendar days before the time of the
sale or disposition.

                                  Section Five
                                    No Waiver

        No delay or omission on the part of the Secured Party in exercising any
right under the Collateral Note or this Security Agreement shall operate as a
waiver of such right or of any other right under the Collateral Note or this
Security Agreement. A waiver on any one occasion shall not be construed as a bar
to or a waiver of any such right and/or remedy on any future occasion.

                                   Section Six
                                  Governing Law

        This Security Agreement and all rights and obligations under this
Security Agreement, including matters of construction, validity, and
performance, shall be governed by the law of the State of New York. Secured
Party and Borrowers hereby waive the right to any jury trial in any action,
proceeding, or counterclaim brought by either Secured Party or Borrowers against
the other.

                                  Section Seven
                    Representations, Covenants and Warranties

        As inducement to Citizens Telecommunications Company to accept the
Collateral Note, the undersigned represent, covenant and warrant that:

        a)     other terms and conditions and promises of the makers herein:

               i) Sonus Communication Holdings, Inc. will provide quarterly and
               yearend consolidated financial statements within forty-five (45)
               days of the end of each quarter, and year-end financial
               statements within ninety (90) days of the end of the Borrowers'
               fiscal year;

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                                 Section Seven
             Representations, Covenants and Warranties (continued)

               ii) all balance sheets, earnings statements and other financial
               data (including footnotes thereto) which have been or may
               hereafter be furnished to Citizens Telecommunications Company to
               induce it to enter into this Security Agreement or otherwise in
               connection with it, do or shall fairly represent the financial
               condition of the Borrowers and the results of its operations as
               of the dates or the periods for which the same are furnished
               (subject in the case of unaudited quarterly reports to year end
               adjustments), and all other information, reports and other papers
               and data furnished to Secured Party are or shall be at the time
               the same are so furnished accurate and correct in all material
               respects and that Generally Accepted Accounting Principles (GAAP)
               shall be used in preparation of any and all such financial
               statements;

               iii) Borrowers shall not merge this business out of existence
               without the written consent of Secured Party. Borrowers shall not
               enter into any dispositive sales, transfers, assignments or
               leases that are not in the ordinary course of business and that
               exceed One Hundred Thousand Dollars ($100,000) without the
               written consent of Secured Party. Borrowers shall not incur any
               additional debt or credit facility (which shall not include sales
               of unsecured debt securities or convertible debt securities) in
               an amount exceeding $100,000 without the written consent of
               Secured Party which consent shall not be withheld unless Secured
               Party reasonably believes its security will be impaired;

               vi) this Security Agreement, the Collateral Note, and all related
               documents are binding upon Borrowers as well as upon Borrowers'
               successors, representatives and assigns, are legally enforceable
               in accordance with their respective terms; and are not in
               contravention of law or of any order, rule or regulation
               applicable to Borrowers, or any existing agreement or instrument
               of Borrowers.

b) That Sonus Communication Holdings, Inc. and Empire One Telecommunications,
Inc. are duly organized and existing in good standing in and under the law of
the State of Delaware and Empire One Telecommunications is duly qualified to do
business in the State of New York and all other states in which it does or will
carry out business, except where the lack of such qualification would not
reasonably be expected to have a material adverse affect.

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c) That the Collateral Note and this Security Agreement have been duly
authorized by the Board of Directors of Empire One Telecommunications, Inc. and
Sonus Communication Holdings, Inc. and by all required corporate action, have
been duly executed and delivered by the Borrowers and constitutes its legal,
valid and binding agreement and obligation, except as the enforceability thereof
may be limited by bankruptcy, insolvency, fraudulent conveyance, reorganization,
moratorium or other similar laws relating to the enforcement of creditors'
rights generally and by general principles of equity.

d) That Borrowers shall execute all additional documentation and do all other
things reasonably required by Secured Party to perfect its security interest in
the collateral, including, but not limited to:

               i)     The Stock Pledge and Escrow Agreement delivered herewith;

               ii)    UCC Forms 1; and

               iii)   Physical delivery of the shares of stock, as outlined
herein, in Sonus Communication Holdings, Inc. held by W. Todd Coffin and John K.
Friedman to John Churchill, Esq. at VVinthrop, Stimson, Putnam & Roberts ("Stock
Pledge Escrow Agent") at One Battery Park Plaza, New York, New York 10004,
pursuant to the Stock Pledge and Escrow Agreement between Secured Party,
Borrowers, and Stock Pledge Escrow Agent.

e)      Sonus Communication Holdings, Inc. represents and warrants that it has
not granted any prior security interest in or to the Collateral owned by it,
and Empire One Telecommunications, Inc. represents and warrants that it has not
granted any prior security interest in or to the Collateral owned by it.

        All representations, covenants and warranties herein shall survive any
expiration, termination or cancellation of this Security Agreement and shall
continue to bind the undersigned, their successors, heirs and assigns.

                                  Section Eight
                                   Amendments

        This Security Agreement, the Collateral Note, and any related documents,
constitute the entire understanding and agreement of the parties as to the
matters set forth in this Security Agreement. No alteration of or amendment to
this Security Agreement shall be effective unless given in writing and signed by
the party or parties to be charged or bound by the alteration or amendment.

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                                  Section Nine
                                     Notice

      Any notice required or permitted to be given by either Borrowers or
Secured Party under this Security Agreement shall be in writing and shall be
personally delivered, sent by overnight courier service or sent by certified or
registered letter or by telecopy confirmed by registered or certified letter to
the other Party at its address set forth below. If mailed, notices will be
deemed effective three (3) working days after deposit, postage prepaid, in the
mail.

        To Secured Party:

        Attn: Suzann B. Duffy
        Citizens Telecommunications Company
        3 High Ridge Park
        Stamford, Connecticut 06905

        with a copy to the Legal Department at the same address;

        To Borrower (Empire One Telecommunications, Inc.):
        Attn: John K. Friedman
        Empire One Telecommunications, Inc.
        254 West 31st Street
        New York, NY 10001

        with a copy to:

        David Bronston, Esquire
        Wolf, Block, Shore and Solis-Choen LLP
        250 Park Avenue
        New York, NY  10177

        To Borrower (SONUS Communication Holdings, Inc.)

        Richard D. Rose
        Chief Financial Officer
        SONUS Communication Holdings, Inc.

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        1600 Wilson Boulevard, Suite 1008
        Arlington, VA  22209

        With a copy to:

        Cecil E. Martin III, Esquire
        McGuire Woods, Battle & Boothe LLP
        7 St. Paul Street, Suite 1000
        Baltimore, MD  21202

                                   Section Ten
                                  Severability

        If a court of competent jurisdiction finds any provision of this
Security Agreement to be invalid or unenforceable as to any person or
circumstance, such finding shall not render that provision invalid or
unenforceable as to any other persons or circumstances. If feasible, any such
offending provision shall be deemed to be modified to be within the limits of
enforceability or validity; however, if the offending provision cannot be so
modified, it shall be stricken and all other provisions of this Security
Agreement in all other respects shall remain valid and enforceable.

BORROWER ACKNOWLEDGES HAVING READ ALL THE PROVISIONS OF THIS SECURITY AGREEMENT,
AND BORROWER AGREES TO ITS TERMS. THIS SECURITY AGREEMENT IS DATED AS OF March
29, 2000.

BORROWER:

SONUS COMMUNICATION HOLDINGS, INC.

By: /s/ W. Todd Coffin
   -------------------------------
        W. Todd Coffin
        Chief Executive Officer

EMPIRE ONE TELECOMMUNICATIONS, INC.

By: /s/ John K. Friedman
   -------------------------------
        John K. Friedman
        Chief Executive Officer

SECURED PARTY:

CITIZENS TELECOMMUNICATIONS COMPANY

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By: /s/ Charles J. Weiss
   -------------------------------

Its: Secretary
    ------------------------------

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