<PAGE>   1


EXHIBIT 4.2

                                 LOAN AGREEMENT


This agreement is made effective April 5, 1999, between Amerilink Corporation,
     an Ohio corporation ("Borrower"), and KeyBank National Association, a
     national banking association ("Lender").

                             Background Information

A.   Borrower has applied to Lender for a $10,000,000 revolving line of credit
     (the "Revolving Loan").

B.   Lender has approved Borrower's application for the Revolving Loan by the
     commitment letter dated March 9, 1999 (the "Loan Commitment"), and Lender
     is willing to make the Revolving Loan to Borrower but only on the terms and
     subject to the conditions set forth in the Loan Commitment, this agreement,
     and the Loan Documents (defined in Section 2, below).

                             Statement of Agreement

Borrower and Lender acknowledge the accuracy of the foregoing Background
Information and hereby agree as follows:

Section 1.  Loan; Use of Loan Proceeds. On the terms and subject to the
            conditions set forth in this agreement, the Loan Commitment, and the
            Loan Documents (as defined below), Lender shall lend to Borrower on
            a revolving basis, in one or more loans, advances of funds, or other
            extensions of credit (each an "Advance") from time to time during
            the period beginning on the date of this agreement and ending on
            April 6, 2001 (the "Availability Period"), an amount up to, but not
            in excess of, $10,000,000.00 (the "Maximum Amount"); provided that
            the Bank shall not be obligated to make any Advance hereunder if
            immediately after giving effect to the requested Advance, the
            aggregate unpaid principal amount of all Advances outstanding would
            exceed the Maximum Amount. The aggregate unpaid principal amount of
            all Advances and interest thereon outstanding on April 6, 2001 (the
            "Termination Date"), shall be due and payable on the Termination
            Date. After the Termination Date, the Borrower shall not be entitled
            to receive and the Lender shall not be obligated to make or
            otherwise fund any Advance. Borrower shall use the proceeds of the
            Revolving Loan to finance working capital and other general
            corporate purposes.

Section 2.  Evidence of Indebtedness and Security for the Revolving Loan. The
            Revolving Loan shall be evidenced by a Revolving Variable Rate
            Cognovit Promissory Note (the "Revolving Note"), a copy of which is
            attached to this agreement as Exhibit A and incorporated into this
            agreement by reference. The Note and Loan Agreement shall be
            referred to collectively as the "Loan Documents."

Section 3.  Rate of Interest; Terms of Payments; Late Charges; Prepayment
            Charges; and Default. The rate of interest, terms of payment, late
            charges, prepayment charges, and default rates for the Revolving
            Loan shall be those set forth in the Revolving Note and this
            agreement.

Section 4.  Term of Loans. The principal balance of the Revolving Note and
            accrued interest thereon shall be due and payable in accordance with
            the Revolving Note, and the entire unpaid principal balance of the
            Revolving Note and all accrued and unpaid interest thereon shall be
            due and payable on or before the "Maturity Date" as set forth in the
            Revolving Note.

Section 5.  Commitment Fee. Borrower shall pay a fee of $2,500 at the end of
            each six-month period that lapses prior to the first request for an
            Advance. In addition, after the first Advance, Borrower shall pay a
            commitment fee on the unused portion of the Loan which shall be
            billed to Borrower quarterly in arrears at a rate of 1/8% per annum.
            The foregoing fees are hereinafter collectively referred to as the
            "Commitment Fee".

Section 6.  Costs and Expenses. In addition to the payment of the Commitment
            Fee, Borrower shall pay or reimburse Lender, as applicable, for all
            of Lender's out-of-pocket costs and expenses relating to, or
            incidental with, the Revolving Note,



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            including without limitation costs and expenses relating to
            administration of the Revolving Note and Lender's attorneys' fees
            (including costs and expenses) whether incurred before or after the
            Closing (collectively, "Lender's Costs").

Section 7.  Depository Requirements. No later than October 1, 1999, Borrower
            shall move its primary depository/cash management relationship to
            Lender. Cash management fees associated with the Depository
            Requirements shall be negotiated subsequent to the Closing of the
            Revolving Note.

Section 8.  Representations, Warranties, and Affirmative Covenants. Borrower
            represents, warrants, and covenants, as applicable, that all of the
            following statements are true and correct as of the date of this
            agreement and shall continue to be true and correct until such time
            as the Revolving Note is paid in full and all of Borrower's
            obligations under this agreement and the Loan Documents are
            satisfied in full:

(a)  Borrower is a corporation duly organized, validly existing, and in good
     standing under the laws of the State of Ohio and is qualified to do
     business and is in good standing in all jurisdictions in which it is
     required to be so qualified and has the corporate power and authority to
     own its properties and assets and to transact the business in which it is
     engaged.

(b)  There has been no material adverse change in Borrower's financial
     statements and other documents and materials submitted to Lender with
     Borrower's application for the Revolving Loan since the period covered by
     such statements, documents and materials.

(c)  Borrower has not employed or engaged any broker, finder, or agent who may
     claim a commission or fee relating to the Revolving Loan, and Borrower
     shall indemnify and hold Lender harmless from any such claim, demand, or
     litigation resulting therefrom.

(d)  Borrower has full power and authority to execute and deliver this agreement
     and the Loan Documents and to perform and observe its obligations under
     this agreement and the Loan Documents; and this agreement and the Loan
     Documents have been duly and validly executed and delivered by Borrower and
     are the legal, valid, and binding obligations of Borrower enforceable in
     accordance with their respective terms.

(e)  Neither the execution or delivery of this agreement or the Loan Documents,
     nor the consummation of any of the transactions contemplated by this
     agreement or the Loan Documents, nor compliance with the terms and
     provisions of this agreement or the Loan Documents, will contravene or
     conflict with: (i) any provision of law, statute, or regulation to which
     Borrower or any of its properties is subject; (ii) any judgment, license,
     order, or permit applicable to Borrower or any of its properties; (iii) any
     indenture, mortgage, or other agreement or instrument to which Borrower is
     a party or by which Borrower or any of its properties is subject or bound;
     or (iv) Borrower's articles of incorporation, code of regulations,
     qualifications to do business in any state, or any actions or proceedings
     of Borrower. No consent, approval, authorization, or order of any court or
     governmental authority or third party is required in connection with the
     execution, delivery, and performance by Borrower of this agreement or the
     Loan Documents. Borrower shall promptly provide Lender with certified
     copies of the documents used to effectuate any amendments to its articles
     of incorporation, code of regulations, or other organizational documents,
     as the case may be.

(f)  To the best of Borrower's knowledge after reasonable investigation,
     Borrower is not in default under any agreement, indenture, mortgage, deed
     of trust, security agreement, lease, franchise, or other obligation to
     which it is a party or by which it or any of its property is bound which
     would have a material adverse affect on the business, prospects, profits,
     properties or financial condition of Borrower. To the best of Borrower's
     knowledge after reasonable investigation, Borrower is not in violation of
     any law, ordinance, governmental rule, or regulation to which it is
     subject, which violation might materially adversely affect the business,
     prospects, profits, properties, or financial condition of Borrower. To the
     best of Borrower's knowledge after reasonable investigation, no event has
     occurred and is continuing which constitutes an Event of Default (as
     defined in Section 11, below) or would, with the lapse of time or giving of
     notice or both, constitute such a default.


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(g)  Borrower shall comply with all applicable laws, rules, regulations, and all
     orders of any governmental authority, a breach of which could materially
     and adversely affect its business or credit.

(h)  To the best of Borrower's knowledge after reasonable investigation, there
     are no claims, suits, or causes of action (whether legal, equitable, or
     administrative) pending or threatened against Borrower which will or may
     have a material adverse affect on the properties, business, prospects,
     profits, or financial condition of Borrower or the ability of Borrower to
     consummate or perform the transactions contemplated by this agreement or
     the Loan Documents.

(i)  Borrower is not in default or delinquent in the payment of any type of tax
     or assessment with any governmental entity which will or may have a
     material adverse affect on the properties, business, prospects, profits, or
     financial condition of Borrower or the ability of Borrower to consummate or
     perform the transactions contemplated by this agreement or the Loan
     Documents.

(j)  Borrower is not a party to any contract or agreement which is not referred
     to herein, contemplated hereby, or previously disclosed in writing to
     Lender, which materially adversely affects Borrower. There is no fact that
     Borrower has not disclosed in writing to Lender which could materially or
     adversely affect the properties, business, prospects, or conditions
     (financial or other) of Borrower. Borrower shall comply in all material
     respects with all material agreements, indentures, mortgages or documents
     binding on it or affecting its properties or business.

(k)  Borrower shall use the proceeds of the Revolving Loan solely for those uses
     permitted under Section 1.

(l)  Borrower shall furnish to Lender, promptly upon becoming aware of the
     existence of any condition or event constituting an Event of Default or
     which, with the giving of notice or lapse of time or both, would constitute
     an Event of Default under this agreement or any Loan Document, a written
     notice specifying the nature and period of existence thereof and what
     action Borrower is taking or proposes to take with respect thereto.

(m)  Upon becoming aware thereof, Borrower shall promptly notify Lender in
     writing of (i) any material adverse change in its financial condition or
     business, (ii) any default under any material agreement, contract or other
     instrument to which Borrower is a party or by which any of its properties
     are bound, or any acceleration of the maturity of any indebtedness owing by
     Borrower, and (iii) any material adverse claim against or affecting
     Borrower.

(n)  Borrower shall maintain proper books of account and records containing
     entries of all of the transactions entered into by Borrower in accordance
     with generally accepted accounting principles.

(o)  Borrower shall preserve and maintain its corporate existence and all of its
     rights, privileges and franchises necessary or desirable in the normal
     conduct of its business, and conduct its business in an orderly and
     efficient manner consistent with good business practices and in accordance
     with all valid regulations and orders of any governmental authority.

(p)  All of the properties and operations of Borrower of a character usually
     insured by persons or entities of established reputation engaged in the
     same or similar business similarly situated are adequately insured, by
     financially sound and reputable insurers, against loss or damage of the
     kinds and in the amounts customarily insured against by such persons or
     entities; and Borrower carries, with one or more such insurers, in
     customary amounts, such other insurance, including public and product
     liability insurance, as is usually carried by persons or entities of
     established reputation engaged in the same or a similar business similarly
     situated. Borrower shall maintain workers' compensation insurance,
     liability insurance, casualty insurance and other insurance on its present
     and future properties, assets and business against such casualties, risks
     and contingencies, and in such types and amounts, as are prudent and
     customary in the industry and as Lender may from time to time reasonably
     request.

(q)  Borrower shall pay when due all taxes, assessments, and other governmental
     charges imposed upon it or its assets, franchises, business, income, or
     profits before any penalty or interest accrues thereon, and all claims
     which would or may have a material adverse affect on Borrower (including
     without limitation claims for labor, services, materials, and



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     supplies) for sums which by law might be a lien or charge upon any of its
     assets; provided that (unless any material item or property would be lost,
     forfeited, or materially damaged as a result thereof) no such charge or
     claim need be paid if it is being diligently contested in good faith by
     Borrower, if Lender is notified in advance of such contest, and if Lender
     receives adequate reserve or other appropriate security acceptable to
     Lender to protect the Lender against any loss therefrom.

(r)  Borrower shall deliver, or cause to be delivered, to Lender: (i) year-end
     financial statements prepared in accordance with generally accepted
     accounting principles for Borrower, audited by a firm of independent
     accountants, not later than 120 days after the expiration of each fiscal
     year of Borrower; (ii) not later than 45 days after the end of each fiscal
     quarter, quarterly balance sheets and income statements prepared in a form
     satisfactory to Lender certified as being true, accurate, and complete by
     the Chief Financial Officers of the Borrower; and (iii) all other
     information or documentation (financial or otherwise), including without
     limitation, financial statements, tax returns, income statements, balance
     sheets, accounts receivable and accounts payable agings relating to
     Borrower upon request of Lender from time to time.

(s)  All representations and warranties made by Borrower herein shall survive
     the delivery of the Revolving Note and the making of the Revolving Loan,
     and any investigation at any time made by or on behalf of Lender shall not
     diminish Lender's rights to rely thereon. All statements contained in any
     certificate or other instrument delivered by or on behalf of Borrower by
     one of its officers under or pursuant to this agreement or the other Loan
     Documents or in connection with the transactions contemplated hereby or
     thereby shall constitute representations and warranties made by Borrower
     hereunder.

(t)  Borrower shall furnish such other information and documentation as the
     Lender may reasonably request.

Section 9.  Negative Covenants. In addition to the affirmative covenants set
            forth in Section 8, until such time as the Revolving Note is paid in
            full and all of Borrower's obligations under this agreement and the
            Loan Documents are satisfied in full, Borrower shall not (unless
            Lender consents in writing):

(a)  Incur, create, assume, have outstanding, guaranty or otherwise be or become
     directly or indirectly liable in respect of any Indebtedness except
     Permitted Indebtedness.

For purposes of this Section 9(a), "Indebtedness" shall mean (i) all obligations
     of Borrower for borrowed money (including without limitation all notes
     payable and drafts accepted representing extensions of credit, all
     obligations evidenced by bonds, debentures, notes or other similar
     instruments and all obligations upon which interest charges are customarily
     paid); (ii) all obligations under conditional sale or other title retention
     agreements and all obligations issued or assumed as full or partial payment
     for property, whether or not any such obligations represent obligations for
     borrowed money; (iii) all indebtedness secured by any Additional
     Encumbrances (as defined in Section 9(b), below) existing on property owned
     or acquired by Borrower subject to any such Lien, whether or not the
     obligations secured thereby shall have been assumed; (iv) all indebtedness
     guaranteed (other than by endorsement of negotiable instruments for
     collection in the ordinary course of business), directly or indirectly, in
     any manner, by Borrower, or in effect guaranteed, directly or indirectly,
     by Borrower through an agreement contingent or otherwise: (A) to purchase
     securities or indebtedness, (B) to purchase, sell or lease (as lessee or
     lessor) property or to purchase or sell services primarily for the purpose
     of enabling the debtor to make payment of the indebtedness or to assure the
     owner of the indebtedness against loss, (C) to supply funds to or in any
     other manner invest in the debtor, or (D) to repay amounts drawn down by
     beneficiaries of letters of credit, whether or not issued directly or
     indirectly for the account of Borrower; (v) all indebtedness for which
     Borrower has agreed, contingently or otherwise, to advance or supply funds;
     and (vi) indebtedness of any joint venture, partnership or other person or
     entity for which Borrower is liable. Obligations under leases shall be
     treated as Indebtedness only to the extent shown as such on Borrower's
     balance sheet prepared in accordance with generally accepted accounting
     principles. Indebtedness shall not include the long-term portion of
     deferred federal income taxes.

For purposes of this Section 9(a), "Permitted Indebtedness" shall mean
     Indebtedness to finance specific capital expenditures not to exceed in the
     aggregate during the Availability Period the amount of $4,000,000.00.


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(b)  Create or suffer to exist any Additional Encumbrances upon any of its
     property or assets now owned or hereafter acquired, except Permitted
     Encumbrances.

For purposes of this Section 9(b), "Additional Encumbrances" shall mean any
     lien, mortgage, security interest, tax lien, pledge, encumbrance or
     conditional sale or title retention arrangement, or any other interest in
     property designed to secure the repayment of indebtedness, whether arising
     by agreement or under any statute or law or otherwise.

For purposes of this Section 9(b), "Permitted Encumbrances" shall mean: (i)
     purchase money security interests and liens securing Permitted Indebtedness
     of the type described in the above definition of Permitted Indebtedness;
     (ii) pledges or deposits made to secure payment of workers' compensation,
     or to participate in any fund in connection with workers' compensation,
     unemployment insurance, pensions, or other social security programs; (iii)
     landlords' liens for rent not yet due and payable; (iv) liens securing the
     payment of taxes due and payable or claims of mechanics, materialmen,
     warehousemen, carriers, and operators; and (v) liens for taxes not yet due
     and payable; provided that liens of the types described in items (ii)
     through (iv) of this definition shall be "Permitted Encumbrances" only so
     long as: (A) the validity or amount of such claims is being contested in
     good faith by appropriate and lawful proceedings, and (B) levy and
     execution on such Liens have been stayed and continue to be stayed..

(c)  With the exception of loans and advances to non-consolidated Affiliates and
     Related Parties which may not exceed $1,000,000 in the aggregate during the
     Availability Period, make or have outstanding any loans, advances of funds,
     or other extensions of credit to any person or entity. For purposes of this
     agreement the terms "Affiliates" and "Related Parties" shall mean: (i) any
     non-consolidated corporation, proprietorship, firm, partnership, limited
     liability company, limited liability partnership, trust, association or
     other entity which, directly or indirectly, is owned or controlled, is
     under common ownership or control with, or is owned or controlled by,
     Borrower; or (ii) any person who is a director, officer, employee, member,
     manager or partner of Borrower or is, directly or indirectly, the
     beneficial owner of 10 percent or more of any class of equity securities of
     the Borrower.

(d)  Directly or indirectly declare or pay any dividend, distribution or other
     payment on any shares of any class of Borrower's stock, or make any other
     distribution to the holders of its securities.

(e)  Except in the ordinary course of business and not to exceed $5,000,000 in
     any one fiscal year during the Availability Period, transfer, sell, assign,
     convey, lease, or otherwise dispose of any of Borrower's properties,
     rights, assets, or business.

(f)  Amend its articles of incorporation, code of regulations, or other
     organizational documents without the prior written consent of Lender, which
     consent shall not be unreasonably withheld or delayed.

(g)  Dissolve or liquidate, or merge or consolidate with or into any other
     person or entity.

(h)  Without the written consent of Lender which shall not be unreasonably
     withheld, directly or indirectly, repurchase, redeem or retire more than
     25% of its outstanding shares of stock or other securities.

(i)  Change its fiscal year or method of accounting.

(j)  Enter into any asset purchase agreement or acquisition agreement(s) that
     would cause the Borrower's balance sheet leverage (defined as Total
     Liabilities divided by Tangible Net Worth (defined as Borrower's total
     assets excluding intangible assets (i.e. goodwill, trademarks, patents,
     copyrights, organizational expenses and similar intangible items, but
     including leaseholds and leasehold improvements) less Borrower's Total
     Liabilities) (the "Balance Sheet Leverage") to exceed a ratio of 1.25:1.00
     on a post-acquisition/pro-forma basis.

(k)  Have capital expenditures exceeding the aggregate of $5,000,000 (the
     "Capital Expenditures Limitation") in any one fiscal year; however if
     Borrower's Balance Sheet Leverage is less than or equal to a ratio of
     1.25:1.00 on a post-



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     acquisition/pro-forma basis and Tangible Net Worth is greater than or equal
     to $20,000,000, the Capital Expenditures Limitation shall be increased to
     $10,000,000.

Section 10. Closing Deliveries; Existence and Authority. At or prior to the
            Closing, Borrower shall have delivered or caused to be delivered to
            Lender, unless specifically waived by Lender in writing, the
            following items, each of which shall be in form and content
            satisfactory to Lender:

(a)  Fully-executed originals of this agreement and all of the Loan Documents.

(b)  All items, instruments, documents, certificates listed on the attached
     Exhibit A and all other matters and documents required to be furnished by
     Borrower at or prior to the Closing under this agreement, the Loan
     Commitment, any of the Loan Documents or otherwise required by Lender.

(c) Payment of all of Lender's Costs.

(d)  Certified Articles of Incorporation and Certificate of Good Standing for
     Borrower from the Ohio Secretary of State.

(e)  Copy of Borrower's articles of incorporation, and all amendments thereto,
     as filed with the Ohio Secretary of State, certified by Borrower's
     secretary as being true, accurate, and complete.

(f)  Copy of Borrower's code of regulations certified by the Borrower's
     secretary as being true, accurate, and complete.

(g)  Resolutions of Borrower approving the execution, delivery and performance
     of this agreement, the Revolving Note, and all other Loan Documents and the
     transactions contemplated herein and therein, each duly adopted by the
     Board of Directors of Borrower, and accompanied by a certificate of the
     secretary or assistant secretary of Borrower stating that such resolutions
     are true and correct, have not been altered or repealed, do not violate or
     conflict with Borrower's articles of incorporation, code of regulation,
     other organizational documents, or actions by the shareholders of Borrower,
     and are in full force and effect.

(h)  A certificate of the secretary of Borrower, which shall certify the names
     of the officers of Borrower authorized to sign each of the Loan Documents,
     together with the true signatures of such officers. Lender may conclusively
     rely on such certificate until it shall receive a further certificate of
     the secretary or assistant secretary of Borrower canceling or amending the
     prior certificate and submitting the signatures of the officers named in
     such further certificate.

(i)  Any other documents, items, instruments, insurance policies, certificates,
     and all other matters that Lender reasonably requests.

Section 11. Events of Default. The occurrence of any of the following events
            shall be an Event of Default under this agreement and all of the
            Loan Documents:

(a)  The determination by Lender, acting on written advice of its legal counsel
     which shall be furnished to Borrower, that any representation or warranty
     made by Borrower in this agreement (including without limitation those
     representations and warranties set forth in Section 8) or any of the Loan
     Documents is materially false or misleading in any material respect when
     made.

(b)  The failure by Borrower to pay the full amount of any installment of
     interest or principal and interest when due under the Revolving Note.

(c)  The failure by Borrower to perform or observe any covenant, condition, or
     obligation contained in this agreement or any of the Loan Documents
     (excluding those monetary obligations covered under (b), above, and
     excluding the



                                      -53-
<PAGE>   7


     representations and warranties covered under (a), above) which failure
     continues uncured for 20 days after delivery by Lender to Borrower of
     notice of such failure.

(d)  The filing of a voluntary or involuntary petition in bankruptcy or
     insolvency or for reorganization, arrangement, adjustment, liquidation,
     dissolution or composition or for the appointment of a receiver, guardian,
     or trustee by or against Borrower.

(e)  The making of an assignment for the benefit of creditors by Borrower or
     Borrower's failure generally to pay its debts as they become due.

(f)  The dissolution, merger, reorganization, or other change in the corporate
     structure of Borrower, without the prior written consent of Lender.

(g)  The entry of a final judgment or lien in excess of $250,000 against
     Borrower which final judgment or lien is not satisfied, discharged or
     bonded-off within 10 days after the date of entry of such judgment or lien,
     or, with respect to any collection action relating to such judgment or
     lien, in the event such collection action is not stayed so as to prevent
     the issuance of a certificate of judgment against Borrower within 10 days
     after the date of entry of such judgment or lien.

(h)  The concealment or removal by Borrower of any part of its property with
     intent to hinder, delay, or defraud its creditors or any of them, or the
     making or suffering of a transfer of any of its property which may be
     fraudulent under any bankruptcy, fraudulent conveyance, or similar law, or
     the making by Borrower of any transfer of its property to or for the
     benefit of a creditor at a time when other creditors similarly situated
     have not been paid, or any other action by Borrower which results in
     Borrower permitting any creditor to obtain a lien upon any of its property
     through legal proceedings which is not vacated within 10 days from the date
     thereof.

Upon the occurrence of any of the above-described events, Lender may declare the
     Revolving Note due and payable upon demand without presentment, protest,
     notice, or demand of any kind. Borrower shall not have the opportunity to
     cure any default if such failure is incapable of being cured, in Lender's
     reasonable discretion, or if the failure is described under any of (a),
     (b), (d), (e), (f) and (g).

Section 12. Procedure for Borrowing under Revolving Loan. Provided all
            conditions described in this Section 12 are satisfied, Borrower may
            borrow under the Revolving Loan on any Business Day (meaning a day
            other than a Saturday, Sunday or other day on which commercial banks
            in Columbus, Ohio, are authorized or required by law to close)
            provided that the Borrower gives the Lender telephonic or written
            notice (each, a "Notice of Borrowing") which must be received by the
            Lender prior to 1:00 p.m., Columbus, Ohio, time, on the requested
            Borrowing Date (as defined below) for each Revolving Loan
            disbursement, specifying (i) the requested Borrowing Date of such
            borrowing, which shall be a Business Day and (ii) the aggregate
            amount of such requested borrowing. Each borrowing pursuant to the
            Revolving Loan shall be in an aggregate principal amount equal to or
            greater than $10,000. Upon receipt of each such Notice of Borrowing
            from the Borrower, the Lender shall deposit such requested borrowing
            for the benefit of the Borrower on the requested Borrowing Date,
            subject to the satisfaction of the terms and conditions of this
            agreement, by crediting the loan account on the books of the Lender
            in the amount of such requested borrowing. Lender is hereby
            authorized, and may at its option, but shall have no obligation to,
            record the date and amount of each borrowing made in connection with
            the Revolving Loan, and the date and the amount of each payment or
            prepayment of principal thereof, on its separate written or
            electronic records maintained in the ordinary course of its
            business, and any such recordation shall constitute prima facie
            evidence of the accuracy of the information so recorded; however,
            the failure of the Lender to make such recordations shall not effect
            the obligations of the Borrower to repay outstanding principal,
            interest or any other amounts due hereunder or under the Revolving
            Note in accordance with the terms hereof and thereof.

The obligation of Lender to continue making disbursements pursuant to the
     Revolving Note until the Maturity Date as set forth in the Revolving Note
     and this agreement is subject to the following conditions:


                                      -54-
<PAGE>   8

(a)  The determination by Lender, acting on written advice of its legal counsel
     which shall be furnished to Borrower, that the representations, warranties
     and covenants made by Borrower in this agreement or any other Loan
     Document, and any representations, warranties and covenants made by
     Borrower which are contained in any certificate, document or financial or
     other statement furnished at any time under or in connection herewith or
     therewith, are true and correct in all material respects as of the date the
     Lender makes a disbursement to Borrower pursuant to the Revolving Note (the
     "Borrowing Date").

(b)  No Event of Default shall have occurred and be continuing on the Borrowing
     Date.

(c)  There shall have been no material adverse change in the financial condition
     (which shall be defined as the Balance Sheet Leverage exceeding a ratio of
     1.25 to 1.00) or no material adverse change in the business of either
     Borrower and its Affiliates from the date of the most recent quarterly
     financials furnished to Lender prior to the Borrowing Date.

(d)  All resolutions, certificates, corporate and other proceedings and all
     other documents and legal matters in connection with the transactions
     contemplated by this agreement and the Loan Documents shall have been
     provided prior to the Borrowing Date in form and substance reasonably
     satisfactory to Lender.

Each time Lender makes an Advance to Borrower under the Revolving Note pursuant
     to a request by Borrower, it shall constitute a representation, warranty
     and covenant by Borrower that, as of the Borrowing Date, the conditions
     contained in paragraphs (a), (b), (c) and (d) of this Section 12 have been
     fully satisfied.

Section 13. Assignment. No rights under this agreement nor in or to the proceeds
            of the Revolving Loan may be assigned by Borrower without the prior
            written consent of Lender.

Section 14. Non-Waiver. No failure by either party to insist upon strict
            compliance with any term of this agreement or to exercise any
            option, enforce any right, or seek any remedy upon any default of
            the other party shall affect, or constitute a waiver of, the first
            party's right to insist upon that strict compliance, exercise that
            option, enforce that right, or seek that remedy with respect to that
            default or any prior, contemporaneous, or subsequent default. No
            custom or practice of the parties at variance with any provision of
            this agreement shall affect, or constitute a waiver of, either
            party's right to demand strict compliance with the provisions of
            this agreement.

Section 15. Notices. All notices and other communications under this agreement
            to be made to either Lender or Borrower shall be in writing and
            shall be deemed given when delivered personally, telecopied (which
            is confirmed electronically), or mailed by certified mail (return
            receipt requested) or sent by Federal Express, UPS, or other
            nationally recognized overnight delivery service for overnight
            delivery to that party at the address for that party (or at such
            other address for such party as such party shall have specified in
            notice to the other party):

(a)  If to Lender:

     KeyBank National Association
     88 East Broad Street
     Columbus, Ohio 43215
     Attention:  Roger D. Campbell, Sr. Vice President
     Telecopy No. (614)_______________________________

     With a copy to:

     Baker & Hostetler LLP
     65 East State Street, Suite 2100
     Columbus, Ohio 43215
     Attention:  Michael D. Bridges, Esq.


                                      -55-
<PAGE>   9

     Telecopy No. (614) 462-2616

(b) If to Borrower:

     Amerilink Corporation
     1900 E. Dublin-Granville Road
     Columbus, Ohio 43229
     Attention:  James Brittan, Vice President - Finance
     Telecopy No. (614)

Section 16. Governing Law. All questions concerning the validity or meaning of
            this agreement or relating to the rights and obligations of the
            parties with respect to performance under this agreement shall be
            construed and resolved under the laws of Ohio.

Section 17. Venue. The parties to this agreement hereby designate the Court of
            Common Pleas of Franklin County, Ohio, as a court of proper
            jurisdiction and exclusive venue for any actions or proceedings
            relating to this agreement; hereby irrevocably consent to such
            designation, jurisdiction, and venue; and hereby waive any
            objections or defenses relating to jurisdiction or venue with
            respect to any action or proceeding initiated in the Court of Common
            Pleas of Franklin County, Ohio.

Section 18. Severability. It is the intention of the parties to comply fully
            with all laws and public policies, and this agreement shall be
            construed consistently with such laws and public policies to the
            extent possible. If and to the extent that any court of competent
            jurisdiction is unable to so construe any provision of this
            agreement and holds that provision to be invalid, that invalidity
            shall not affect the remaining provisions of this agreement, which
            shall remain in full force and effect.

Section 19. Time is of the Essence. Time is of the essence relating to this
            agreement and with respect to all other obligations to be performed
            under this agreement, but delay in the exercise by Lender of its
            rights hereunder shall not be deemed a waiver of such right by
            Lender.

Section 20. Captions. The captions at the beginning of the Sections and several
            subSections of this agreement are not part of the context of this
            agreement, but are only labels to assist in locating those Sections
            and subSections, and shall be ignored in construing this agreement.

Section 21. Jury Trial Waiver. Borrower and Lender, after consulting or having
            the opportunity to consult with legal counsel, knowingly,
            voluntarily and intentionally waives any right it may have to a
            trial by jury in any action or proceeding based upon or arising out
            of this agreement or any of the Loan Documents or any course of
            conduct, dealings, statements, whether oral or written, or actions
            of either party. Borrower and Lender shall not seek to consolidate,
            by counterclaim or otherwise, any action in which a jury trial has
            been waived with any other action in which a jury trial cannot be or
            has not been waived.

Section 22. No Third Party Benefit. This agreement is intended for the exclusive
            benefit of the parties and their respective heirs, successors and
            assigns. Nothing contained in this agreement shall be construed as
            creating any rights or benefits in or to any third party.

Section 23. Complete Agreement. This document, along with the Loan Documents,
            contains the entire agreement among the parties and supersedes any
            prior discussions, negotiations, representations, or agreements
            among them respecting the subject matter. No additions or other
            changes to this agreement shall be made or be binding unless made in
            writing and signed by each party to this agreement.



                                      -56-
<PAGE>   10

AMERILINK CORPORATION                               KEYBANK NATIONAL ASSOCIATION




By:_______________________________          By:_________________________________
     (Name)                (Title)             (Name)                    (Title)







                     VARIABLE RATE COGNOVIT PROMISSORY NOTE

$10,000,000.00                                                     April 5, 1999

For value received, the undersigned, Amerilink Corporation, an Ohio corporation,
     with offices at 1900 E. Dublin-Granville Road, Ohio 43229 (hereinafter
     referred to as "Maker"), promises to pay to the order of KeyBank National
     Association, a national banking association (hereinafter referred to as
     "Payee," which term shall include any holder hereof), at its principal
     place of business at 88 East Broad Street, Columbus, Ohio 43215, or at such
     other place as Payee may designate, the principal sum of Ten Million
     Dollars ($10,000,000), or so much thereof as may be advanced by Payee to
     Maker from time to time, together with all charges herein provided and
     interest on the unrepaid advances of said principal sum from the date of
     disbursement by Payee, payable in cash at the rates and in the manner
     hereinafter set forth.

                                    ARTICLE I
                                   DEFINITIONS

1.1  The following terms wherever used in this Note shall have the following
     meanings:

"Advance" shall mean any loan, advance of funds, or extension of credit under
     the Loan Agreement.

"Default Rate of Interest" shall mean the Prime Rate of Interest as may be
     charged by Lender.

"Loan Agreement" shall mean that certain Loan Agreement dated April 5, 1999
     pursuant to which the principal amount of this Note is to be disbursed, by
     which Payee agrees to loan funds to Maker pursuant to the terms and
     conditions stated therein.

"Loan Documents" shall collectively mean this Note, Loan Agreement and any other
     instrument, affidavit, certificate or document heretofore, now or hereafter
     given by Maker in connection with the closing of the loan evidenced by this
     Note.

"Maturity Date" shall mean April 6, 2001.

"Note" shall mean this Variable Rate Cognovit Promissory Note.

"Prime Rate" shall mean the interest rate established and announced from time to
     time by Maker as its prime rate, based upon its consideration of economic,
     money market, business and competitive factors, and it is not necessarily
     the most



                                      -57-
<PAGE>   11

     favorable rate of Maker. Each change in said Prime Rate shall, without
     notice, automatically and immediately change the rate of interest due
     hereon.

"Variable Rate" shall mean the rate equal to the Prime Rate minus 125 basis
     points (bps).



                                   ARTICLE II
                       PAYMENTS OF PRINCIPAL AND INTEREST

2.1  From and after the date of this Note, interest on the unrepaid advances of
     the principal sum from date of disbursement by Payee at the Variable Rate
     shall be due and payable monthly on the first day of each month after the
     initial advance and continuing on the first day of each month thereafter
     through the Maturity Date.

2.2  All interest payable in accordance with this Note shall be calculated on
     the basis of the actual number of calendar days elapsed but computed on a
     daily basis as if each year consisted of 360 days.

2.3  All principal and all accrued and unpaid interest shall be due and payable
     in full on the Maturity Date.

2.4  In the event that any applicable law, treaty, rule or regulation now or
     hereafter in effect, or any interpretation or administration thereof by any
     governmental authority charged with the interpretation or administration
     thereof, or compliance by Payee with any request or directive of any such
     authority (whether or not having the force of law) (each of the foregoing
     being referred to as a "Regulatory Requirement"), shall (a) impose, modify
     or deem applicable any reserve, special deposit or similar requirement
     against assets of, deposits with or for the account of, or credit extended
     by Payee, or (b) impose any other condition, requirement or charge with
     respect to this Note or the Loan Documents (including, without limitation,
     any capital adequacy requirement, any requirement which affects the manner
     in which Payee allocates capital resources to its commitments or any
     similar requirement), and the result of any of the foregoing change in
     external conditions is to increase the actual cost to Payee of making or
     maintaining the loan evidenced by this Note (the "Loan") or any Advance
     hereunder, to reduce the actual amount of any sum receivable by Payee
     thereon, or to reduce the actual rate of return on the capital of Payee
     from the actual cost, sum receivable or rate of return applicable on the
     date of this Note, then Maker shall pay to Payee, from time to time, upon
     request of Payee, additional amounts sufficient to compensate Payee for
     such increased cost, reduced sum receivable or reduced rate of return
     (collectively, "Reduced Earnings") to the extent Payee is not compensated
     therefor in the computation of the interest rates applicable to the Loan. A
     detailed statement as to the amount of such increased cost, reduced sum
     receivable or reduced rate of return, prepared in good faith and submitted
     by Payee to Maker, shall be conclusive and binding for all purposes, absent
     manifest error in determination. Payee shall promptly notify Maker of any
     event occurring after the date of this Note that entitles Payee to
     additional compensation pursuant to this Section. This provision is for the
     benefit of Payee and is not intended to increase the yield to Payee above
     the rates of interest provided for in this Note.

                                   ARTICLE III
                                  LATE CHARGES

3.1  If any of said payments of principal or interest or any combination thereof
     are not paid in full within five days after such payment is due, then in
     addition to the amount of said payment Lender shall have the right to
     assess, and Maker promises to pay, a late charge in respect of each said
     payment in the amount of 5% which Maker agrees is a fair and reasonable
     charge for costs incurred by Payee in processing such late payment and
     shall not be deemed a penalty.

                                   ARTICLE IV
                                   PREPAYMENT



                                      -58-
<PAGE>   12

4.1  This Note evidences a loan in the form of a revolving line of credit, and
     Maker may, subject to the applicable provisions under this Note and the
     Loan Agreement, borrow, repay, and re-borrow sums an unlimited number of
     times.

4.2  The privilege is hereby reserved by Maker to prepay this Note in whole or
     in part at any time and from time to time without premium or penalty,
     provided that Payee shall receive written notice of Maker's intention to so
     prepay not less than three days prior to such prepayment and further
     provided that a payment of all accrued and unpaid interest applicable to
     the portion of the principal amount to be prepaid, to the date of such
     prepayment, is included with such prepayment.

                                    ARTICLE V
                                     DEFAULT

5.1  The term "Event of Default" shall mean the occurrence of any one or more of
     the following:

(a)  A failure by Maker to make any payment of principal or interest or any
     combination thereof under this Note within twenty (20) days when due.

(b)  The material incorrectness of any representation or warranty made by Maker
     to Payee in any of the Loan Documents or any financial statement or other
     document delivered to Payee in connection with the Loan.

(c)  The inability of Maker to satisfy any one or more of the conditions
     specified in the Loan Agreement as precedent to the obligation of Payee to
     make a loan disbursement after an application for a loan disbursement has
     been submitted by Maker to Payee.

(d)  The failure of Maker to observe, perform or comply with any of the other
     terms, covenants or conditions of Maker set forth in the Loan Documents and
     to cure such failure within the time period, if any, specified therein.

5.2  Upon the occurrence of any Event of Default, the entire unpaid balance of
     principal and interest evidenced by this Note, together with all sums of
     money advanced by Payee in accordance with the terms of the Loan Agreement,
     and all sums due and owing for any late charge or charges hereunder (the
     foregoing being hereinafter collectively referred to as the "Indebtedness")
     shall thereupon bear interest at the Default Rate of Interest, and at the
     option of Payee, all the Indebtedness together with interest at the Default
     Rate of Interest shall immediately become due and payable ("Acceleration")
     without demand made therefor and without notice to any person, notice of
     the exercise of said option being hereby expressly waived, and Payee shall
     have all remedies of a secured party under law and equity to enforce the
     payment of all of the Indebtedness, time being of the essence of this Note.
     The Default Rate of Interest shall be charged to Maker upon the occurrence
     of any Event of Default notwithstanding any invoices or billing statements
     sent by Payee to Maker indicating an interest rate to the contrary. In
     addition, any waiver of Payee's right to charge the Default Rate of
     Interest or to accelerate the Indebtedness must be made in writing and
     cannot be waived by oral representation or the submission to Maker of
     monthly billing statements.



                                   ARTICLE VI
                                  MISCELLANEOUS

6.1  The failure of Payee to exercise any option herein provided upon the
     occurrence of any Event of Default shall not constitute a waiver of the
     right to exercise such option in the event of any continuing or subsequent
     Event of Default. Maker hereby agrees that the maturity of all or any part
     of the Loan may be postponed or extended and that any covenants and
     conditions contained in this Note or in any of the other Loan Documents may
     be waived or modified without prejudice to the liability of Maker on said
     Note or Loan Documents.



                                      -59-
<PAGE>   13

6.2  Maker hereby authorizes Payee, in its sole discretion, upon the occurrence
     of an Event of Default, to apply all or any portion of the balance of any
     account, other than the Borrower's account for payroll, taxes and employee
     contribution which shall be maintained in separate accounts by Payee,
     maintained by Maker with Payee to the payment or reduction, in whole or in
     part, of any and all principal and interest then due, whether by
     acceleration or otherwise, to Payee under this Note. Upon the occurrence of
     any Event of Default, Payee shall have the right to setoff against all
     obligations of Maker to Payee hereunder, whether matured or unmatured, all
     amounts owing to Maker by Payee, whether or not then due and payable, and
     all other funds or property of Maker on deposit with or otherwise held in
     the custody of Payee or any of its affiliates, all without notice to or
     demand on Maker, such notice and demand being hereby waived.

6.3  Presentment for payment, notice of dishonor, protest, notice of protest and
     diligence in bringing suit against any party hereto are hereby waived by
     Maker.

6.4  Maker hereby waives all relief from any and all appraisement or exemption
     laws now in force or hereafter enacted.

6.5  The obligations evidenced or created by this Note, as well as all waivers
     of rights by Maker contained herein, shall effectively bind and be the
     obligations and waivers of any and all others who may at any time become
     liable for the payment of all or any part of this Note, including without
     limitation all indorsers and guarantors.

6.6  Nothing herein contained, nor in any of the other Loan Documents or other
     documents relating hereto, shall be construed or so operate as to require
     Maker, or any person liable for the payment of the Loan, to pay interest in
     an amount or at a rate greater than the highest rate permissible under
     applicable law. Should any interest or other charges paid by Maker, or any
     parties liable for the payment of the Loan, result in the computation or
     earning of interest in excess of the highest rate permissible under
     applicable law, then any and all such excess shall be and the same is
     hereby waived by Payee, and all such excess shall be automatically credited
     against and in reduction of the principal balance, and any portion of said
     excess which exceeds the principal balance shall be paid by Payee to Maker
     and any parties liable for the payment of the loan made pursuant to this
     Note, it being the intent of the parties hereto that under no circumstances
     shall Maker or any parties liable for the payment of the loan hereunder be
     required to pay interest in excess of the highest rate permissible under
     applicable law. All interest paid or agreed to be paid to Payee shall, to
     the extent permitted under applicable law, be amortized, prorated,
     allocated and spread throughout the full period until payment in full of
     this Note, including the period of any renewal or extension thereof, so
     that interest thereon for such full period shall not exceed the maximum
     amount permitted by applicable law.

Notwithstanding anything to the contrary herein contained, in the event that the
     Variable Rate should ever exceed the highest rate permissible under
     applicable law, thereby causing the interest accruing on the Indebtedness
     to be limited to such highest rate permissible under applicable law, then
     any subsequent reduction in the Prime Rate shall not reduce the rate of
     interest charged hereunder below the highest rate permissible under
     applicable law until the total amount of interest accrued on the
     Indebtedness equals the amount of interest which would have accrued on such
     indebtedness if the Variable Rate had been in effect at all times in the
     period during which the rate charged thereon was limited to the highest
     rate permissible under applicable law.

6.7  If any provision (or any part of any provision) contained in this Note
     shall for any reason be held or deemed to be invalid, illegal or
     unenforceable in any respect, such invalidity, illegality or
     unenforceability shall not affect any other provision (or remaining part of
     the affected provision) of this Note, and this Note shall be construed as
     if such invalid, illegal or unenforceable provision (or part thereof) had
     never been contained herein and the remaining provisions of this Note shall
     remain in full force and effect.

6.8  Maker hereby authorizes any attorney-at-law to appear in any court of
     record in the State of Ohio or in any other state or territory of the
     United States at any time after this Note becomes due, whether by
     acceleration or otherwise, to waive the issuing and service of process, and
     to confess judgment against Maker in favor of Payee for the amount due
     together with interest, expenses, the costs of suit and reasonable counsel
     fees, and thereupon to release and waive all errors, rights of appeal and
     stays of execution. Such authority shall not be exhausted by one exercise,
     but judgment may be confessed



                                      -60-
<PAGE>   14


     from time to time as any sums and/or costs, expenses or reasonable counsel
     fees shall be due, by filing an original or a photostatic copy of this
     Note. Maker waives any right to move any court for an order having any
     attorney or firm representing Payee removed or disqualified as counsel for
     Payee as a result of such attorney or firm confessing judgment against
     Maker in accordance with this Section 6.10. Maker hereby expressly waives
     any conflicts of interest that may now or hereafter exist as a result of
     any attorney representing Payee confessing judgment against Maker and
     expressly consents to any attorney representing Payee or to any other
     attorney to confess judgment against Maker in accordance with this Section
     6.8. Maker hereby further consents and agrees that Payee may pay any
     attorney confessing judgment and that any fees so paid may be included in
     the amount of such judgment.

6.9  Maker hereby agrees to pay to Payee all costs of collecting and securing,
     and of attempting to collect and to secure this Note, including without
     limitation reasonable attorneys' fees, appraisers' fees, court costs, and
     notice charges, whether such attempt be made by suit, in bankruptcy, or
     otherwise, and said costs and any other sums due Payee by virtue of this
     Note may be included in any judgment or decree rendered.

This Note is delivered in the State of Ohio and is to be governed by and
     construed in accordance with the laws of the State of Ohio. In addition to
     any other appropriate jurisdiction determined by Payee, Maker hereby
     consents to and, by execution of this Note, submits to the personal
     jurisdiction of the Court of Common Pleas of Franklin County, Ohio and the
     United States District Court sitting in Columbus, Ohio for the purposes of
     any judicial proceedings which are instituted for the enforcement of this
     Note. Maker agrees that venue is proper in said jurisdiction.

WARNING -- BY SIGNING THIS PAPER YOU GIVE UP YOUR RIGHT TO NOTICE AND COURT
     TRIAL. IF YOU DO NOT PAY ON TIME A COURT JUDGMENT MAY BE TAKEN AGAINST YOU
     WITHOUT YOUR PRIOR KNOWLEDGE AND THE POWERS OF A COURT CAN BE USED TO
     COLLECT FROM YOU REGARDLESS OF ANY CLAIMS YOU MAY HAVE AGAINST THE CREDITOR
     WHETHER FOR RETURNED GOODS, FAULTY GOODS, FAILURE ON HIS PART TO COMPLY
     WITH THE AGREEMENT, OR ANY OTHER CAUSE.

                                  AMERILINK CORPORATION



                                  By____________________________________________
                                  Print Name____________________________________
                                  Its___________________________________________








                                      -61-