Document:

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                                                                 Exhibit 10.1.21

                        ADVANCED TELECOMMUNICATIONS, INC.
                             1433 Utica Avenue South
                         South Plaza Building, Suite 70
                         St. Louis Park, Minnesota 55416

                                  July 1, 1996

Mr. Clifford D. Williams
5044 Juanita Avenue South
Edina, MN 55424

Dear Cliff:

            This letter will confirm your employment commencing as of the date
of this letter by Advanced Telecommunications Inc., a Minnesota corporation (the
"Company"). This letter is being executed in connection with that certain Stock
Purchase Agreement (the "Purchase Agreement") dated as of even date herewith by
and between the Company and the holders of all of the issued and outstanding
stock of Cady Communications, Inc., a Minnesota corporation ("CCI"), under which
agreement and others the Company has agreed to purchase all of the issued and
outstanding capital stock of CCI.

            1. Employment. You are hereby employed by the Company as its Chief
Executive Officer. In that capacity, it is expected that you will perform on a
full-time basis such duties as may from time to time be assigned to you by the
Board of Directors of the Company ("the Board") not inconsistent with your
training and experience.

            2. Consideration.

            2.1. Salary. Initially, you will receive an annual base salary of
$130,000 payable in equal installments no less frequently than monthly. The
Board or its Compensation Committee will review your base salary on an annual
basis taking into account market conditions in the Minneapolis, Minnesota area
in that review, provided that any increase in your base salary will be as
determined by the Board or its Compensation Committee in its reasonable
discretion, but will be fair and comparable to the market taking into account
base salary, bonuses, stock options, other compensation and benefits.

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            2.2. Withholding Taxes. The amounts payable to you under this
Paragraph 2 are before any deductions from such amounts for any taxes required
to be withheld by any federal, state or local government. The Company will have
the right to rely on a written opinion of legal counsel, which may be
independent legal counsel or legal counsel regularly employed by the Company, if
any question should arise as to any such deductions.

            2.3. Incentive Stock Options. In addition to your base salary, your
compensation includes the incentive stock options described in that certain
Stock Option Agreement of even date herewith between the Company and you.

            2.4. Incentive Pay. For each of the Company's fiscal years during
the term of your employment by the Company, the Board or its Compensation
Committee will establish performance goals which, if achieved, will entitle you
to bonuses, in the amounts as determined by the Board or its Compensation
Committee aggregating up to 120% of your base salary for that fiscal year as
determined by the Company. The bonus payable each year will be determined on the
basis outlined on attached Schedule A. For each fiscal year during your
employment, the Board or its Compensation Committee will make such
determinations and notify you of them within ninety (90) days after the
commencement of such fiscal year. The bonuses payable for any fiscal year will
be paid to you within 120 days of the end of the fiscal year to which such
bonuses are attributable. The bonus payable for the fiscal year during which
your employment terminates will be pro rated to the date of termination, but
payable as provided in the previous sentence.

            3. Benefits. You will be entitled to participate in such vacation,
health insurance, disability insurance, retirement, and such other fringe
benefit plans, if any, as provided by the Company to its executive officers from
time to time. Such benefits will at least be comparable to those currently
provided by CCI.

            4. Employment Status. Nothing herein shall be construed to result in
any commitment with regard to your continued employment, which the Company and
you agree is at-will.

            5. Non-Competition. By your execution of this letter, you agree to
abide by the restriction set forth in this Paragraph 5 and acknowledge that you
have received good and valuable for agreeing to those restrictions.

            5.1. Definitions. For purposes of this Paragraph 5, the following
definitions apply:

                                       2.
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            (a) "Customer" means (i) during the term of your employment with the
Company, CCI or any other Related Entity, any Person which, at any time during
the term of your employment by the Company, CCI or any other Related Entity
(including, without limitation, your employment by the Company prior to the date
of this letter), purchased products or services from, or was solicited to
purchase products or services from, the Company, CCI or any other Related
Entity, and (ii) during the Restricted Period, any Person which, at any time
during the 2 year period immediately prior to the date of termination of your
employment with the Company, CCI and the Related Entities (including, without
limitation, your employment by the Company prior to the date of this letter),
purchased products or services from, or was solicited to purchase products or
services from, the Company, CCI or any other Related Entity.

            (b) "Confidential Information" means information learned or acquired
by you during your employment by the Company, CCI or any other Related Entity
(whether before or after the date of this letter), including without limitation,
(i) all technical information relating to the Company, CCI or any other Related
Entity; (ii) any information concerning any product or service under development
by, or being tested by, the Company, CCI or any other Related Entity but not yet
offered for sale; (iii) any information concerning the pricing policies of the
Company, CCI or any other Related Entity, the prices charged by the Company, CCI
or any other Related Entity to any Customer, the volume of orders of any
Customer, any bids or negotiations being submitted by or being conducted by the
Company, CCI or any other Related Entity and all other information concerning
the transactions of the Company, CCI or any other Related Entity with any
Customer or proposed Customer; (iv) any information concerning the marketing
programs or strategies of the Company, CCI or any other Related Entity; (v) any
financial information concerning the salaries or wages paid to, the work records
of or any other personnel information relating to any employee of the Company,
CCI or any other Related Entity; and (vi) any other information determined by
the Company, CCI or any other Related Entity to be confidential and proprietary
and which is identified as confidential and proprietary prior to or at the time
of its disclosure to you. The foregoing to the contrary notwithstanding, no
information will be considered to be "Confidential Information" which is (x)
disclosed or published after the date of this Agreement through no fault of
yours, or (y) becomes

                                       3.
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general public information without disclosure by you after the date of this
Agreement.

            (c) "Person" means an individual, partnership, joint venture,
corporation, business trust, joint stock company, trust, unincorporated
organization, governmental authority or other entity of whatever nature.

            (d) "Related Entity" means CCI and any other subsidiary of the
Company.

            (e) "Restricted Period" means the 2-year period immediately
following the date you cease to be an employee of the Company, CCI and all
Related Entities.

            (f) "Restricted Territory" means the State of Minnesota and the area
within 100 miles of any sales office or other facility operated by the Company,
CCI or any Related Entity anywhere outside of the State of Minnesota at any time
during the term of your employment by the Company, CCI and/or any the Related
Entities.

            (g) "Subject Businesses" means (i) during the term of your
employment with the Company, CCI or any other Related Entity, any businesses
which compete with the businesses conducted by the Company, CCI or any other
Related Entity, and (ii) during the Restricted Period, any businesses which
compete with any of those businesses conducted by the Company, CCI or any other
Related Entity at any time during the two (2) year period immediately prior to
the date of termination of your employment with the Company, CCI and the Related
Entities.

            (h) "Subject Products" means (i) during the term of your employment
with the Company, CCI or any other Related Entity, those products which the
Company, CCI or any other Related Entity sold, resold, serviced, leased, rented,
distributed or maintained at any time during the term of your employment with
the Company, CCI or any other Related Entity (whether such employment was before
or after the date of this letter), and (ii) during the Restricted Period, those
products which the Company, CCI or any other Related Entity sold, resold,
serviced, leased, rented, distributed or maintained at any time during the two
(2) year period immediately prior to the date of termination of your employment
with the Company, CCI and the Related Entities.

            (i) "Supplier" means (i) during the term of your employment with the
Company, CCI or any other Related Entity, any Person which, at any time during
the term of

                                       4.
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      your employment by the Company, CCI or any other Related Entity
      (including, without limitation, your employment by the Company prior to
      the date of this letter), sold products or services to the Company, CCI or
      any other Related Entity, or and (ii) during the Restricted Period, any
      Person which, at any time during the 2 year period immediately prior to
      the date of termination of your employment with the Company, CCI and the
      Related Entities (including, without limitation, your employment by the
      Company prior to the date of this letter), sold products or services to
      the Company, CCI or any other Related Entity.

            5.2. Non-Competition. You will not during the term of your
employment or any time thereafter during the Restricted Period, directly or
indirectly, whether as agent, stockholder (except as the holder of not more than
5% of the stock of a publicly held company, provided you do not participate in
the business of that publicly held company or render advice or assistance to
it), employee, officer, director, trustee, partner, consultant, proprietor or
otherwise, except on behalf of the Company, CCI or any other Related Entity:

                  (a) Acquire an ownership interest in, engage in or render
      advice or assistance to any business which sells, resells, services,
      leases, rents, distributes or maintains any of the Subject Products or
      which otherwise competes with the Subject Businesses anywhere in the
      Restricted Territory.

                  (b) Entice or attempt to entice any of the Suppliers or
      Customers, or any Person with whom CCI or any Related Entity is
      negotiating or to whom CCI or any Related Entity has submitted a bid, so
      as to cause, or attempt to cause, any Supplier or Customer not to do
      business, or reduce its business, with the Company, CCI or any Related
      Entity or to purchase from any other Person any of the Subject Products.

                  (c) Hire or attempt to hire any employees, contractors or
      agents of the Company, CCI or any other Related Entity, or attempt to
      induce any of those parties to leave their employment, agency or
      independent contractor relationship with the Company, CCI or any other
      Related Entity. Nothing herein shall be construed to limit or restrict you
      from hiring any agent of the Company, CCI or any other Related Entity, or
      any person providing services to the Company, CCI or any other Related
      Entity as an independent contractor.

            5.3. Confidential Information. You will not, during your employment
with the Company, CCI or any other Related Entity

                                       5.
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or at any time thereafter during the five (5) year period after the termination
of your employment by the Company, CCI and the Related Entities, disclose any
Confidential Information to any Person other than an employee or agent of the
Company, CCI or any other Related Entity having the need to know that
information in the ordinary course of business, or to a Person to whom a
disclosure has been authorized by the Board of Directors of the Company.

            5.4. Remedies in the Event of Breach. You recognize that irreparable
injury may result to the Company, CCI and the other Related Entities and their
businesses and properties in the event of a breach by you of the restrictions
imposed by this Paragraph 5, and your acceptance of those restrictions was a
material factor in the Company's decision to employ you as provided in this
letter. Your engagement in any act in violation of this Paragraph 5 will entitle
the Company, in addition to any other remedies and damages available to it, to
an injunction prohibiting you from engaging in those acts.

            5.5. Reasonableness of Restrictions. By entering into this
Agreement, you acknowledge (i) that you are familiar with the nature of the
business of the Company, CCI and CCI's subsidiary, Cady Management, Inc., and
their products and services; (ii) that you have read and understand the nature
and scope of the restrictions imposed by this Paragraph 5; and (iii) that the
Company, CCI and the other Related Entities have invested and will continue to
invest substantial effort any sums of money to develop and promote their
products and services and the goodwill of their respective businesses. YOU
THEREFORE ACKNOWLEDGE AND REPRESENT THAT THE SCOPE OF THOSE RESTRICTIONS ARE
APPROPRIATE, NECESSARY AND REASONABLE FOR THE PROTECTION OF THE BUSINESS,
GOODWILL AND PROPERTY RIGHTS OF THE COMPANY, CCI AND ANY OTHER RELATED PARTY AND
WILL NOT PREVENT YOU FROM EARNING A LIVING SUBSEQUENT TO THE DATE OF THIS
AGREEMENT. Notwithstanding anything contained in this Agreement to the contrary,
the terms of this Agreement do not constitute a waiver by the Company, CCI or
any other Related Entity of any of their rights in, or to protect specific items
of, any information or materials which constitute trade secrets, or a release or
limitation of your legal obligation not to disclose or misappropriate any trade
secrets of the Company, CCI or any other Related Entity at any time during or
after your employment with the Company, CCI or any other Related Entity.

                                       6.
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the benefit of the successor of the Company resulting from such merger,
consolidation or transfer. This letter will not be assignable by you without the
prior written consent of the Company.

            6.4. Waiver of Breach. The waiver by the Company of the breach of
any of the provisions of this letter will not be considered a waiver by the
Company of any subsequent breach.

            6.5. Binding Effect. This letter will be binding upon and inure to
the benefit of the parties to this letter and their respective heirs,
successors, assigns and legal representatives.

            6.6. Partial Invalidity. If any provision of this letter is found to
be invalid or unenforceable for any reason, this letter will be construed with
the invalid or inoperative provision deleted and the remaining covenants,
sections or portions of this Agreement will remain in full force and effect.

            6.7. Governing Law. The internal laws of Minnesota will govern this
letter and all questions of its interpretation, performance, enforceability and
the rights and remedies of the parties to this letter will be determined in
accordance with such laws.

            If the terms and conditions of this letter are satisfactory to you,
please execute it on the lines provided below and return an executed copy to the
undersigned.

                                   Very truly yours,

                                   ADVANCED TELECOMMUNICATIONS, INC.

                                   By: /s/ Paul D. Cady
                                       -----------------------------
                                       Paul D. Cady, President

Accepted and agreed to as of this
1st day of July, 1996.

/s/ Clifford D. Williams
---------------------------------
Clifford D. Williams

                                       8.
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                                   SCHEDULE A

      The Company will develop a bonus plan for its fiscal year ending June 30,
1997, and each fiscal year thereafter, which will entitle you to bonuses based
on (a) the Company achieving financial ratios or other financial performance
measurements established by the Board, in its reasonable discretion, (b)
business acquisitions consummated during the fiscal year by the Company,
directly or through one of its subsidiaries, (c) the customer satisfaction level
achieved by the Company for the fiscal year and (d) your job performance as
determined by the Board or its Compensation Committee, in its reasonable
discretion. The Board or its Compensation Committee may, in its sole discretion,
establish other and/or alternative goals from time to time for determining
bonuses in fiscal years beginning on or after July 1, 1997.

      The bonus plan will allow you to earn a bonus of up to 60% of your base
salary if you achieve a base level of performance in all categories, up to 90%
of your base salary if performance in all categories is above the
budgeted/target level, and up to 120% of your base salary of performance in all
categories is above the "stretch" level and significantly higher than the base
level. The bonus calculation for each category will be determined by the product
of the percentage applicable to the performance level achieved in each category,
multiplied by the percentage weighting applicable to the category in question,
multiplied by your base salary for the year. The foregoing to the contrary
notwithstanding, the bonus pool established by the Company for the year will be
based on a budget/target level of an appropriate measure of operating cash-flow
("Cash-Flow") of the Company for the year. If Cash-Flow falls below that level,
and the final pool is therefore less than the aggregate amount of the bonuses
otherwise payable by the Company to all its employees for the year based on the
Company bonus schedule applicable to the employees of the Company, the amount
calculated under the bonus schedule described above will be proportionately
reduced along with the bonuses of other employees entitled to bonuses based on
such shortfall in the bonus pool. Furthermore, a bonus will only be payable if
the Company achieves Cash-Flow level base for the fiscal year, as will be
defined in the annual business plan approved each year by the Board or its
Compensation Committee in its reasonable discretion.

                                       9.Exhibit 10.1.22

[LETTERHEAD OF ADVANCED TELECOMMUNICATIONS, INC.]

To:         Satish Tiwari

From:       Richard A. Smith, Chief Financial Officer

Date:       April 15, 1999

Subject:    Outline of Employment Offer to Satish Tiwari

I am pleased to present the following outline of Advanced Telecommunications,
Inc., (ATI) offer to you for the position of Vice President -- Engineering and
Network Implementation.

1.    Annual Direct Compensation
      Annual compensation will be $140,000 per year.

2.    Incentive Compensation
      You will be eligible for an annual performance incentive pay package that
      could max out at 60% of your annual base pay. The performance targets will
      be based on the following metrics:

            Revenue
            Gross Margin
            Consolidated EBITDA
            Customer Satisfaction

      Performance incentive targets and pay will be assessed and granted
      quarterly upon completion of the year-end audit, reviewed and approved by
      the ATI Board of Directors.

            Base Plan (30%): Will represent the Company's budget on an annual
            basis.

            Target Plan (45%): Will represent the Company's budget adjusted as
            follows:

                              o Revenue = 104% of Budget
                              o Margin = 103% of Budget
                              o EBITDA = 89% of Budgeted Loss

            Premier Plan (60%): Will represent targets above budget that
            represent truly premier performance.

                              o Revenue = 107% of Budget
                              o Margin = 107% of Budget
                              o EBITDA = 79% of Budgeted Loss

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Page 2
April 15, 1999

3.    Change in Control Agreement
      Should there be a change in control at ATI, you will be covered with an
      agreement that provides for the following:
      a)    If the Executive's employment is terminated within 24 months after a
            change in control without cause, then the employee will receive
            severance pay of two (2) times average annual compensation.
      b)    Up to two (2) years of medical coverage or until the employee
            obtains comparable coverage from a new employer.
      Note: A formal Change in Control Severance Pay Agreement will be offered
            to the Executive to sign on employment that will provide detail on
            the above provisions.

4.    "Floor" Value of Options Upon Change in Control
      In consideration of the immediate value that you would bring to ATI, if a
      change in control occurs within the first three (3) years of your
      employment, you may elect to transfer all of your options to the Company
      in exchange for a lump sum payment of $2,000,000 upon change in control
      should you desire. At this point, all of your outstanding stock options
      shall, by reason of the "change-in-control" be deemed earned, vested, and
      exercisable. If Stolberg Partners L.P. fails to realize a 30% annual
      return on its invested capital, then the amount paid to you under this
      letter will be ratably reduced by the percentage amount of the shortfall
      from the foregoing investment target.
      Note: A formal letter will be provided to the Executive to sign on
            employment that will provide detail on the above provisions.

5.    Relocation
      ATI will provide a relocation package to the Executive that is intended to
      allow the employee to remain neutral from a compensation perspective. This
      package will include the following elements:
      a)    Out of pocket costs for home search (up to two family trips).
      b)    All real estate commissions paid to a third party for sale of the
            primary dwelling.
      c)    Points required to make interest rates equivalent to the current
            rate that the Executive pays.
      d)    Closing costs on the sale and purchase of a primary dwelling.
      e)    Temporary living expenses until a residence is occupied in
            Minneapolis if necessary.
      f)    Home travel every week until Executive's family is relocated.
      g)    All household moving expenses with a licensed national moving
            company.
      h)    Reimbursement for (health/dental/vision) benefits from your present
            employers COBRA in Texas until your family relocates to Minnesota.

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Page 3
April 15, 1999

5.    Relocation - continued
      i)    Tax gross up for all of the above (items a-i) in order for the
            Executive to remain cash neutral for the relocation.

6.    Performance Stock Options
      You will be granted 1,500 performance stock options at a strike price of
      $300 per share. The shares will be earned and vested on your anniversary
      date as follows:

                                       Share Vesting    Percent Vesting
                                       -------------    ---------------
         End of Year       One              300               20%
                           Two              300               20%
                           Three            300               20%
                           Four             300               20%
                           Five             300               20%
                                       -------------    ---------------
                           Total          1,500              100%

      You will also be eligible for additional performance option shares at the
      rate of 300 shares per market per voice switch installed (first four (4)),
      also at a strike price of $300 per share. At a minimum, our plan calls for
      four (4) switches; and could call for as many as twenty-one (21) switches.
      The first four (4) switches would carry a strike price of $300 per share
      and for switches beyond the first four (4) -- the exercise price will be
      the then current calculated or actual market value per share of ATI and at
      150 shares per switch.

      Should there be a change of control at ATI, all options granted will
      immediately be earned and vested.

      If the existing private equity funding process does not yield a $300 per
      share price, your exercise price will be the lesser of the private equity
      price per share or $300, whichever is lower.

      It is the objective of management and our key outside investor (Stolberg,
      Meehan and Scano) to increase the value of ATI at an annualized rate of at
      least 30% per year. See the following analysis for the estimated value
      generated by this grant over the next five (5) years:

                                    10%       20%       30%       40%       50%
                                  Growth    Growth    Growth    Growth    Growth
                                  ------    ------    ------    ------    ------
Initial Grant (1500)               $275K    $ 670K    $1221K    $1970K    $2967K
4 Switch Options (1200)             220K      536K      977K     1576K     1978K
                                  ------    ------    ------    ------    ------
  Total                            $495K    $1206K    $2198K    $3546K    $4945K

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Page 4
April 15, 1999

      The above estimates of value are all net of original exercise price of
      $300 per share. Options granted for switch installations beyond the
      initial four (4) markets will have a current value exercise price
      associated with them.

      Note: These estimates of the value of the option grant do not imply any
            guaranteed value -- but are based solely on management's/investor's
            expectations and their internal forecasts.

      As a key member of the ATI executive team, you will also eligible for
      additional option grants based on your individual performance and
      performance of ATI.

7.    Other Benefits
      You will also be eligible for a complete range of company benefits,
      including 401(k) (25% match on the first 6% contributed), health club
      membership reimbursement (family reimbursement is $35.00 per month),
      medical coverage, and company paid parking.

8.    Contingencies
      This offer is contingent upon successful completion of a physical
      examination, reference/background checks, and successful negotiation out
      of any/all non-competes that you may have with your existing company.

9.    ATI Financing Plan
      ATI is currently in the process of obtaining additional funding which will
      allow us to proceed with the switch build-out and to add additional
      infrastructure necessary for CLEC operations. Because of this -- I want to
      make this offer contingent upon securing appropriate financing at a level
      that will provide for a minimum level of infrastructure build-out.

10.   Investment in ATI
      With your employment with ATI and providing for a floor value of options
      outlined in #4 above of $2.0M, you will be allowed to purchase $200K of 8%
      Convertible Subordinated Promissory Notes convertible into shares of the
      Company's Class A common stock at the rate of $300 per share.

Satish -- I am looking forward to working with you.

Accepted by: /s/ Satish Tiwari                         Date: April 22, 1999
             -----------------------------
             Satish Tiwari

<PAGE>

               [LETTERHEAD OF ADVANCED TELECOMMUNICATIONS, INC.]

                                 April 20, 1999

Mr. Satish Tiwari
4208 Toledo Avenue
Fort Worth, TX 76133

Dear Satish:

This letter is intended to supplement the terms of my April 15, 1999 letter to
you detailing the terms of your employment by ATI. ATI has granted you options
to purchase 1,500 shares of ATI common stock at a price of $300.00. These
options will vest over a five year period, so long as ATI achieves the financial
performance targets established each year by its Board of Directors.

You have also purchased a $200,000 Series B 8% Convertible Subordinated
Promissory Note issued by ATI and dated as of April 20, 1999 (the "Note"). The
Note is convertible into shares of ATI Class A common stock at the price of
$300.00 per share.

This will confirm our mutual understanding that in the event of any
"change-in-control" (as defined in the Change-in-Control Severance Pay Agreement
between you and ATI) of ATI on or before April 20, 2002, you may elect to
receive a lump sum cash payment, not later than 30 days after the date of the
"change-in-control," of $2,000,000 (net of the $200,000 purchase price of the
Note) in exchange for your transfer to ATI of the Note and all of your stock
options. All of your outstanding stock options shall, by reason of the
"change-in-control," be deemed earned, vested and exercisable.

If in connection with a "change in control," Stolberg Partners L.P. fails to
realize on its investment in ATI's Preferred Stock sold by it, an annually
compounded rate of return of 30% or more and if Stolberg Partners, L.P. and
Stolberg, Meehan & Scano II, L.P. fail to realize on their investment in any
other ATI securities sold by them, an annually compounded internal rate of
return of 30% or more, then the amount to be paid you under this letter shall be
ratably reduced by the percentage amount (determined on a blended basis) of the
shortfall from the foregoing investment targets. To illustrate the foregoing for
clarification purposes and not by way of limitation, if the blended return is
25%, the guarantied payment will be reduced from $2,000,000 to $1,666,667
(i.e., 25%/30% x $2,000,000).

If the foregoing accurately reflects our mutual understanding, please indicate
your acceptance and agreement by signing where indicated below and returning
such signed copy of this letter to me.

                                        Best regards,

                                        /s/ Richard A. Smith     4/20/99

                                        Richard A. Smith
                                        Chief Financial Officer

RAS/cak

ACCEPTED ON APRIL 22, 1999.

/s/ Satish Tiwari
---------------------------
Satish Tiwari

<PAGE>

                    CHANGE-IN-CONTROL SEVERANCE PAY AGREEMENT

      THIS AGREEMENT is made this 22nd day of April, 1999, by and between
ADVANCED TELECOMMUNICATIONS, INC., a Minnesota corporation (the "Company") and
SATISH TIWARI (the "Executive").

                                    RECITALS

      A. The Executive is the Vice President-Engineering and Network
Implementation of the Company as of the date of this Agreement.

      B. The Board of Directors of the Company desires to retain the Executive
in the employ of the Company.

      C. The Board of Director believes that it is essential to preserve and
maintain the stability and continuity of management of the Company by providing
the Executive with economic and other security from the uncertainty of risks
inherent in a potential sale or merger of the Company which might jeopardize the
Executive's employment.

      NOW THEREFORE, in consideration of the foregoing and of the mutual
promises of the patties hereto, the Company and the Executive agree as follows:

      1. Eligibility for Severance Pay. The Executive shall be eligible to
receive severance pay, in the amounts and at the times described in paragraph 3,
if:

            (a) the Executive's employment with the Company and all of its
      subsidiaries (if any) is terminated within 24 months after there has been
      a "change in control," as such term is hereinafter defined; and

            (b) the Executive's termination of employment was not:

                        (i) on account of the Executive's death;

                        (ii) on account of a physical or mental condition that
            entitles the Executive to benefits under any long-term disability
            plan maintained by the Company or any of its subsidiaries, as then
            in effect;

                        (iii) for conduct involving willful misconduct (such as
            commission by the Executive of a felony or a common law fraud
            against the Company) which is detrimental in a significant way to
            the business of the Company or any of its subsidiaries; or

                        (iv) on account of the Executive's voluntary
            resignation; provided, that a resignation shall not be considered to
            be voluntary for the purposes of this Agreement if it occurs under
            the circumstances described in paragraph 10(a), or if,

                                      -1-
<PAGE>

            subsequent to the change in control, there has been: (1) a reduction
            in the Executive's base compensation; or (2) a change in the place
            in which the Executive is required to perform his or her duties, if
            the new place is more than 50 miles from the place Executive
            performed his services immediately prior to the "change in control."

      2. Change in Control. For the purposes of this Agreement, a "change in
control" shall be deemed to have occurred if:

            (a) there occurs any sale or other disposition to a person unrelated
      to the Company or any of the holders of its securities of (i)
      representing, after sale or disposition, more than 50% of the outstanding
      voting securities of the Company as measured by voting power on an as if
      converted basis or (ii) more than 50% of the aggregate assets of the
      Company and its subsidiaries, in the single transaction or series of
      transactions; or

            (b) the Company or any combination of the Company and its
      subsidiaries aggregating more than fifty percent (50%) of the consolidated
      assets of the Company and its wholly-owned subsidiaries becomes a party to
      any merger or consolidation (excluding a merger or consolidation where the
      Company or one of such subsidiaries is the surviving corporation);

and in the case of either (a) or (b) above, Stolberg Partners, L.P. and
Stolberg, Meehan and Scano II, L.P. liquidate more than 50% of their aggregate
voting stock and voting stock equivalents of the Company as measured by the
total votes represented thereby.

      3. Certain Change in Control and Severance Payments. The Executive shall
receive:

            (a) a lump sum cash payment, no later than 30 days after the date on
      which the Executive's employment terminates, in an amount equal to two
      times the Executive's average annual compensation (as defined below); and

            (b) continuation of coverage under the Company's group medical,
      group life, and group long-term disability plans, if any, and under any
      individual policy or policies of life insurance maintained by the Company,
      with the same rate of employer contributions as for active employees,
      until the earlier to occur of

                        (i) the expiration of 24 months from the date on which
            the Executive's employment terminates; or

                        (ii) the date on which the Executive obtains comparable
            coverage provided by a new employer.

            (c) a lump sum cash payment, payable no later than 30 days after the
      date on which the Executive's employment terminates, in an amount equal to
      the sum of:

                                      -2-
<PAGE>

                        (i) the amount by which the fair market value of that
            number of shares of stock subject to any stock option which is
            forfeited or which otherwise becomes nonexercisable by the Executive
            by reason of the termination of his or her employment (determined as
            of the date of such termination) exceeds the option price for such
            shares; and

                        (ii) such additional amounts (or the fair market value
            of such additional property) in excess of the amount determined
            pursuant to subparagraph (1) that would have been paid or
            distributed to the Executive upon the exercise of any such forfeited
            stock options, had such options been exercisable, and exercised, by
            the Executive as of the date his or her employment terminated.

      It is understood and agreed that this payment under this paragraph 3(c) is
      to occur only to the extent the Executive is not entitled to exercise his
      options after the termination of his or her employment under the
      provisions of the Executive's stock option agreements.

For purposes of this paragraph 3, the term "average annual compensation" shall
mean the average rate of annual salary payable to the Executive for the calendar
year in which the Executive's employment terminates and for the two immediately
preceding calendar years, plus the average annual bonus or incentive payments
awarded to the Executive for the same three calendar years; provided, that if
bonus or incentive compensation awards have not been determined for the calendar
year in which the Executive's employment terminates prior to the date of such
termination, such average shall be determined using the bonuses or incentive
payments awarded to the Executive for the three calendar years immediately
preceding the year in which the Executive's employment terminates; and provided
further, that if the Executive has not been employed by the Company for two full
calendar years preceding the year in which the Executive's employment
terminates, "average annual compensation" shall be based on the Executive's
average annual rate of salary plus the average annual bonus or incentive
payments determined as described above, for the entire period of the Executive's
employment. The Executive's average annual compensation shall be determined
prior to any reduction for deferred compensation, "401(k)" plan contributions,
and similar items, and any reduction in the Executive's rate of salary occurring
within 24 months after a change in control shall be disregarded. In addition,
the insurance coverage provided under this paragraph shall be governed by the
insurance coverage provided to such the Executive immediately prior to any
reduction in such coverage occurring within 24 months after any change in
control.

      4. No Funding of Severance Pay. Nothing herein contained shall require or
be deemed to require the Company or a subsidiary to segregate, earmark, or
otherwise set aside any funds or other assets to provide for any payments
required to be made hereunder, and the rights of the terminating Executive to
severance pay hereunder shall be solely those of a general, unsecured creditor
of the Company.

      5. Death. In the event of the Executive's death, any amount or benefit
payable or distributable to the Executive pursuant to paragraph 3(a), 3(b) and
3(c) shall be paid to the beneficiary designated by the Executive for such
purpose in the last written instrument, if any, received by the Boards of
Directors of the Company prior to the Executive's death, or, if no beneficiary
has been designated, to the Executive's estate.

                                      -3-
<PAGE>

      6. Rights in the Event of Dispute. If a claim or dispute arises concerning
the rights of the Executive or a beneficiary to benefits under this Agreement,
regardless of the party by whom such claim or dispute is initiated, the
prevailing party in such dispute shall be entitled to recover its legal
expenses, including reasonable attorneys' fees, court costs, and ordinary and
necessary out-of-pocket costs of attorneys incurred in connection with the
bringing, prosecuting, defending, litigating, negotiating, or settling such
claim or dispute; provided, that:

            (a) the prevailing party obtains a judgment in its favor from a
      court of competent jurisdiction from which no appeal may be taken, whether
      because the time to do so has expired or otherwise; and provided further,
      that

            (b) in the case of any claim or dispute initiated by the Executive,
      such claim shall be made, or notice of such dispute given, with specific
      reference to the provisions of this Agreement, to the Board of Directors
      of the Company within one year after the occurrence of the event giving
      rise to such claim or dispute.

      7. Amendment. This Agreement may not be amended or modified except by a
written instrument signed by both parties as of a date contemporaneous herewith
or subsequent hereto.

      8. No Obligation to Mitigate Damages. In the event the Executive becomes
eligible to receive benefits hereunder the Executive shall have no obligation to
seek other employment in an effort to mitigate damages. To the extent the
Executive shall accept other employment after the termination of his or her
employment, the compensation and benefits received from such employment shall
not reduce any compensation and benefits due under this Agreement, except as
provided in paragraph 3(b).

      9. Other Benefits. The benefits provided under this Agreement shall,
except to the extent otherwise specifically provided herein, be in addition to,
and not in derogation or diminution of, any benefits that the Executive or the
Executive's beneficiary may be entitled to receive under any other plan or
program now or hereafter maintained by the Company or by any of its
subsidiaries.

      10. Successors.

            (a) The Company will require any successor (whether direct or
      indirect, by purchase, merger, consolidation, or otherwise) to all or
      substantially all of the business and/or assets of the Company, to
      expressly assume and agree to perform the Company's obligations under this
      Agreement in the same manner and to the same extent that the Company would
      be required to perform them if no such succession had taken place unless,
      in the opinion of legal counsel mutually acceptable to the Company and the
      Executive, such obligations have been assumed by the successor as a matter
      of law. Failure of the Company to obtain such agreement prior to the
      effectiveness of any such succession (unless the foregoing opinion is
      rendered to the Executive) shall entitle the Executive to terminate his or
      her employment and to receive the payments provided for in paragraph 3
      above; provided that Executive has given notice of such failure to the
      Company after such effectiveness and such agreement is not so assumed
      within ten (10) days after the Company's receipt of such notice. As used
      in this Agreement, "Company" shall mean the Company, as presently
      constituted, and any successor

                                      -4-
<PAGE>

      to its business and/or assets which executes and delivers the agreement
      provided for in this paragraph 10 or which otherwise becomes bound by all
      the terms and provisions of this Agreement as a matter of law.

            (b) The Executive's rights under this Agreement shall inure to the
      benefit of, and shall be enforceable by, the Executive's legal
      representative or other successors in interest, but shall not otherwise be
      assignable or transferable.

      11. Notices. Any notices referred to herein shall be in writing and shall
be sufficient if delivered in person or sent by U.S. registered or certified
mail to the Executive at his or her address on file with the Company (or to such
other address as the Executive shall specify by notice), or to the Company at
730 Second Avenue South, Suite 1200, Minneapolis, Minnesota 55402 Attn: Chief
Executive Officer.

      12. Waiver. Any waiver of any breach of any of the provisions of this
Agreement shall not operate as a waiver of any other breach of such provisions
or any other provisions, nor shall any failure to enforce any provision of this
Agreement operate as a waiver of any party's right to enforce such provision or
any other provision.

      13. Severability. If any provision of this Agreement or the application
thereof is held invalid or unenforceable by a court of competent jurisdiction,
the invalidity or unenforceability thereof shall not affect any other provisions
or applications of this Agreement which can be given effect without the invalid
or unenforceable provision or application.

      14. Governing Law. The validity, interpretation, construction, and
performance of this Agreement shall be governed by the laws of the State of
Minnesota, except to the extent superseded by applicable federal law.

      15. Headings. The headings and paragraph designations of this Agreement
are included solely for convenience of reference and shall in no event be
construed to affect or modify any provisions of this Agreement.

      16. Gender and Number. In this Agreement where the context admits, words
in any gender shall include the other genders, words in the plural shall include
the singular, and words in the singular shall include the plural.

                                      -5-
<PAGE>

      The parties hereto have executed this Agreement as of the day and year
first above written.

         COMPANY:                       ADVANCED TELECOMMUNICATIONS, INC.

                                        By /s/ Richard A. Smith    4/20/99
                                           -----------------------------------
                                           Richard A. Smith
                                           Chief Financial Officer

         EXECUTIVE:
                                        By /s/ Satish Tiwari    April 22, 1999
                                           -----------------------------------
                                           Satish Tiwari
                                           Vice President - Engineering
                                           and Network Implementation

                                      -6-

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