<PAGE>

                                                                   EXHIBIT 10.31

                               SEVERANCE AGREEMENT

                  THIS AGREEMENT is entered into as of October 29, 1999 by and
between Aerial Communications, Inc., a Delaware corporation, and Gary Ballard
(the "Executive").

                  WHEREAS, the Executive currently serves as a key employee of
the Company (as defined in Section 1) or one of its subsidiaries and the
Executives' services and knowledge are valuable to the Company in connection
with the management of one or more of the Company's principal operating
facilities, divisions, departments or subsidiaries;

                  WHEREAS, the Board (as defined in Section 1) has determined
that it is in the best interests of the Company and its stockholders to secure
the Executive's continued services and to ensure the Executive's continued
dedication and objectivity in the event of any threat or occurrence of, or
negotiation or other action that could lead to, or create the possibility of, a
Change in Control (as defined in Section 1) of the Company, so that the
Executive need not be hindered or distracted by personal uncertainties and risks
created by any such possible Change in Control, and to encourage the Executive's
full attention and dedication to the Company, the Board has authorized the
Company to enter into this Agreement.

                  NOW, THEREFORE, for and in consideration of the premises and
the mutual covenants and agreements herein contained, the Company and the
Executive hereby agree as follows:

                  1. DEFINITIONS. As used in this Agreement, the following terms
shall have the respective meanings set forth below:

                  (a) "Affiliate" means a corporation which owns directly or
indirectly at least 50% of the outstanding stock of the Company or the combined
voting power of such outstanding stock, or a corporation at least 50% of whose
outstanding stock or the combined voting power of such outstanding stock is
owned directly or indirectly by the Company.

                  (b) "Board" means the Board of Directors of the Company.

                  (c) "Cause" means (1) a material breach by the Executive of
those duties and responsibilities of the Executive which do not, in the
aggregate, differ materially from the duties and responsibilities of the
Executive during the 90-day period immediately prior to a Change in Control
(other than as a result of incapacity due to physical or mental illness) which
is willful, which is committed in bad faith or without reasonable belief that
such breach is in the best interests of the Company and which is not remedied in
a reasonable period of time after receipt of written notice from the Company
specifying such


<PAGE>

breach, (2) the commission by the Executive of a felony involving moral
turpitude, (3) the commission by the Executive of theft, fraud, breach of trust
or any act of dishonesty involving the Company or any Affiliate or (4) the
significant violation by the Executive of any statutory or common law duty of
loyalty to the Company or any Affiliate.

                  (d) "Change in Control" means a "change in control" with
respect to Telephone and Data Systems, Inc. as described on Exhibit A, at a time
when Telephone and Data Systems, Inc. owns directly or indirectly at least 50%
of either the outstanding stock of the Company or the combined voting power of
such stock, or one of the following events:

                  (1) the acquisition by any individual, entity or group (a
"Person"), including any "person" within the meaning of section 13(d)(3) or
14(d)(2) of the Securities Exchange Act of 1934, as amended (the "Act"), of
beneficial ownership within the meaning of Rule 13d-3 promulgated under the Act
of 25% or more of the combined voting power of the then outstanding securities
of the Company entitled to vote generally on matters (without regard to the
election of directors) (the "Outstanding Voting Securities"), excluding,
however, the following: (i) any acquisition directly from the Company, or an
Affiliate (excluding any acquisition resulting from the exercise of an exercise,
conversion or exchange privilege, unless the security being so exercised,
converted or exchanged was acquired directly from the Company or an Affiliate),
(ii) any acquisition by the Company or an Affiliate, (iii) any acquisition by an
employee benefit plan (or related trust) sponsored or maintained by the Company
or an Affiliate, (iv) any acquisition by any corporation pursuant to a
transaction which complies with clauses (i), (ii) and (iii) of subsection (3)
below, or (v) any acquisition by the following persons: (A) LeRoy T. Carlson or
his spouse, (B) any child of LeRoy T. Carlson or the spouse of any such child,
(C) any grandchild of LeRoy T. Carlson, including any child adopted by any child
of LeRoy T. Carlson, or the spouse of any such grandchild, (D) the estate of any
of the persons described in clauses (A)-(C), (E) any trust or similar
arrangement (including any acquisition on behalf of such trust or similar
arrangement by the trustees or similar persons) PROVIDED THAT all of the current
beneficiaries of such trust or similar arrangement are persons described in
clauses (A)-(C) or their lineal descendants, or (F) the voting trust which
expires on June 30, 2009, or any successor to such voting trust, including the
trustees of such voting trust on behalf of such voting trust (all such persons,
collectively, the "Exempted Persons");

         (2) individuals who, as of the date hereof constitute the Board (the
"Incumbent Board") cease for any reason to constitute at least a majority of
such Board; PROVIDED THAT any individual


                                       2
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who becomes a director of the Company subsequent to the date hereof whose
election, or nomination for election by the Company's stockholders, was approved
by the vote of at least a majority of the directors then comprising the
Incumbent Board shall be deemed a member of the Incumbent Board; and PROVIDED
FURTHER, that any individual who was initially elected as a director of the
Company as a result of an actual or threatened election contest, as such terms
are used in Rule 14a-11 of Regulation 14A promulgated under the Act, or any
other actual or threatened solicitation of proxies or consents by or on behalf
of any Person other than the Board shall not be deemed a member of the Incumbent
Board;

         (3) the consummation of a reorganization, merger or consolidation or
sale or other disposition of all or substantially all of the assets of the
Company (a "Corporate Transaction"), excluding, however, a Corporate Transaction
pursuant to which (i) all or substantially all of the individuals or entities
who are the beneficial owners of the Outstanding Voting Securities immediately
prior to such Corporate Transaction will beneficially own, directly or
indirectly, more than 51% of the combined voting power of the outstanding
securities of the corporation resulting from such Corporate Transaction
(including, without limitation, a corporation which as a result of such
transaction owns, either directly or indirectly, the Company or all or
substantially all of the Company's assets) which are entitled to vote generally
on matters (without regard to the election of directors), in substantially the
same proportions relative to each other as the shares of Outstanding Voting
Securities are owned immediately prior to such Corporate Transaction, (ii) no
Person (other than the following Persons: (v) the Company or an Affiliate, (w)
any employee benefit plan (or related trust) sponsored or maintained by the
Company or an Affiliate, (x) the corporation resulting from such Corporate
Transaction, (y) the Exempted Persons, (z) and any Person which beneficially
owned, immediately prior to such Corporate Transaction, directly or indirectly,
25% or more of the Outstanding Voting Securities) will beneficially own,
directly or indirectly, 25% or more of the combined voting power of the
outstanding securities of such corporation entitled to vote generally on matters
(without regard to the election of directors) and (iii) individuals who were
members of the Incumbent Board will constitute at least a majority of the
members of the board of directors of the corporation resulting from such
Corporate Transaction; or

                  (4) the consummation of a plan of complete liquidation or
dissolution of the Company.

                  (e) "Company" means Aerial Communications, Inc., a Delaware
corporation.


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                  (f) "Date of Termination" means (1) the effective date on
which the Executive's employment by the Company terminates as specified in a
prior written notice by the Company or the Executive, as the case may be, to the
other, delivered pursuant to Section 11 or (2) if the Executive's employment by
the Company terminates by reason of death, the date of death of the Executive.

                  (g) "Good Reason" means, without the Executive's express
written consent, the occurrence of any of the following events after a Change in
Control:

                  (1) any of (i) the assignment to the Executive of a materially
lower level of responsibility or status with the Company than existed
immediately prior to such Change in Control, or (ii) any failure to re-elect the
Executive to any significant office or, if applicable, directorship with the
Company held by the Executive immediately prior to such Change in Control;

                  (2) a reduction by the Company in the Executive's rate of
annual base salary or bonus opportunity as in effect immediately prior to such
Change in Control;

                  (3) any requirement of the Company that (i) the Executive be
based more than 30 miles from the facility where the Executive is located at the
time of the Change in Control or (ii) the Executive increase travel on Company
business by 20% or more than the travel obligations of the Executive immediately
prior to such Change in Control;

                  (4) the failure of the Company to (i) continue in effect any
employee benefit plan or compensation plan in which the Executive is
participating immediately prior to such Change in Control, unless the Executive
is permitted to participate in other plans providing the Executive with
substantially comparable benefits, or the taking of any action by the Company
which would adversely affect the Executive's participation in or materially
reduce the Executive's benefits under any such plan, (ii) provide the Executive
and the Executive's dependents welfare benefits (including, without limitation,
medical, prescription, dental, disability, salary continuance, employee life,
group life, accidental death and travel accident insurance plans and programs)
in accordance with the plans, practices, programs and policies of the Company
and its affiliated companies in effect for the Executive immediately prior to
such Change in Control as in effect generally at any time thereafter with
respect to other peer executives of the Company and its affiliated companies; or

                  (5) the failure of the Company to obtain the assumption
agreement from any successor as contemplated in Section 10(b).


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                  (h) "Nonqualifying Termination" means a termination of the
Executive's employment (1) by the Company for Cause, (2) by the Executive for
any reason other than a Good Reason, (3) as a result of the Executive's death or
(4) by the Company due to the Executive's absence from his duties with the
Company on a full-time basis for at least 180 consecutive days as a result of
the Executive's incapacity due to physical or mental illness.

                  (i) "Termination Period" means the period of time beginning
with a Change in Control and ending on the earlier to occur of (1) two years
following such Change in Control and (2) the Executive's death.

                  2. OBLIGATIONS OF THE EXECUTIVE. The Executive agrees that in
the event any person or group attempts a Change in Control, he shall not
voluntarily leave the employ of the Company without Good Reason (a) until such
attempted Change in Control terminates or (b) if a Change in Control shall
occur, until 90 days following such Change in Control. For purposes of clause
(a) of the preceding sentence, Good Reason shall be determined as if a Change in
Control had occurred when such attempted Change in Control became known to the
Board.

                  3. PAYMENTS UPON TERMINATION OF EMPLOYMENT.

                  (a) If during the Termination Period (i) the employment of the
Executive shall terminate, other than by reason of a Nonqualifying Termination,
and (ii) the Executive (or the Executive's executor or other legal
representative in the case of the Executive's death or disability following such
termination) executes a general release in the form of Exhibit A hereto within
five days following the Executive's Date of Termination and has not revoked such
release, then the Company shall pay to the Executive (or the Executive's
beneficiary or estate) within 30 days following the Date of Termination, as
compensation for services rendered to the Company:

                  (1) a cash amount equal to the sum of (i) the Executive's full
annual base salary from the Company and its affiliated companies through the
Date of Termination, to the extent not theretofore paid, (ii) the Executive's
target bonus for the fiscal year in which the Change in Control occurs,
multiplied by a fraction, the numerator of which is the number of days in the
fiscal year in which the Change in Control occurs through the Date of
Termination and the denominator of which is 365 or 366, as applicable, to the
extent not theretofore paid and (iii) any compensation previously deferred by
the Executive (together with any interest and earnings thereon) and any accrued
vacation pay, in each case to the extent not theretofore paid; plus


                                       5
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                  (2) a lump-sum cash amount (subject to any applicable payroll
or other taxes required to be withheld pursuant to Section 5) in an amount equal
to (i)1.5 times the Executive's highest annual base salary from the Company and
its affiliated companies in effect during the 12-month period prior to the Date
of Termination, plus (ii)1.5 times the Executive's target bonus for the fiscal
year in which the Change in Control occurs, PROVIDED, HOWEVER, that any amount
paid pursuant to this Section 3(a)(2) shall be paid in lieu of any other amount
of severance relating to salary or bonus continuation to be received by the
Executive upon termination of employment of the Executive under any employment
agreement or severance plan, policy or arrangement of the Company, Aerial
Operating Company, Inc., Telephone and Data Systems, Inc. or any other Affiliate
(as determined immediately prior to a Change in Control).

                  (b)(1) In addition to the payments to be made pursuant to
Section 3(a) for a period of 18 months commencing on the Date of Termination,
the Company shall continue to keep in full force and effect all policies of
medical, accident, disability and life insurance with respect to the Executive
and his dependents with the same level of coverage, upon the same terms and
otherwise to the same extent as such policies shall have been in effect
immediately prior to the Date of Termination as provided generally with respect
to other peer executives of the Company and its affiliated companies, and the
Company and the Executive shall share the costs of the continuation of such
insurance coverage in the same proportion as such costs were shared immediately
prior to the Date of Termination.

                  (2) In addition to the payments to be made pursuant to Section
3(a), the Executive shall be entitled to outplacement services to be provided by
a firm selected by the Company, provided that such outplacement services are
commenced within 30 days following the Date of Termination. Payments in the
aggregate amount not to exceed $12,000 shall be made directly to such
outplacement firm upon submission of proper documentation to the Company. If the
Executive elects not to use such outplacement services, the Executive will not
be entitled to cash compensation in lieu thereof.


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                  (c) If during the Termination Period the employment of the
Executive shall terminate by reason of a Nonqualifying Termination, then the
Company shall pay to the Executive within 30 days following the Date of
Termination, a cash amount equal to the sum of (1) the Executive's full annual
base salary from the Company through the Date of Termination, to the extent not
theretofore paid, and (2) any compensation previously deferred by the Executive
(together with any interest and earnings thereon) and any accrued vacation pay,
in each case to the extent not theretofore paid.

                  4. LIMITATION ON PAYMENTS BY THE COMPANY. Solely for the
purposes of the computation of benefits under this Agreement and
notwithstanding any other provisions hereof, payments to the Executive under
this Agreement shall be reduced (but not below zero) so that the present
value, as determined in accordance with Section 280G(d)(4) of the Code, of
such payments plus any other payments that must be taken into account for
purposes of any computation relating to the Executive under Section
280G(b)(2)(A)(ii) of the Code, shall not, in the aggregate, exceed 2.99 times
the Executive's "base amount," as such term is defined in Section 280G(b)(3)
of the Code. Notwithstanding any other provision hereof, no reduction in
payments under the limitation contained in the immediately preceding sentence
shall be applied to payments hereunder which do not constitute "excess
parachute payments" within the meaning of the Code. Any payments in excess of
the limitation of this Section 4 or otherwise determined to be "excess
parachute payments" made to the Executive hereunder shall be deemed to be
overpayments which shall constitute an amount owing from the Executive to the
Company with interest from the date of receipt by the Executive to the date
of repayment (or offset) at the applicable federal rate under Section 1274(d)
of the Code, compounded semi-annually, which shall be payable to the Company
upon demand; provided, however, that no repayment shall be required under
this sentence if in the written opinion of tax counsel satisfactory to the
Executive and delivered to the Executive and the Company such repayment does
not allow such overpayment to be excluded for federal income and excise tax
purposes from the Executive's income for the year of receipt or afford the
Executive a compensating federal income tax deduction for the year of
repayment.

                  5. WITHHOLDING TAXES. The Company may withhold from all
payments due to the Executive (or his beneficiary or estate) hereunder all taxes
which, by applicable federal, state, local or other law, the Company is required
to withhold therefrom.

                  6. REIMBURSEMENT OF EXPENSES. If any contest or dispute shall
arise under this Agreement involving termination of the Executive's employment
with the Company or involving the failure or refusal of the Company to perform
fully in accordance


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with the terms hereof, the Company shall reimburse the Executive, on a current
basis, for all legal fees and expenses, if any, incurred by the Executive in
connection with such contest or dispute, together with interest thereon at a
rate equal to the prime rate, as published under "Money Rates" in THE WALL
STREET JOURNAL from time to time, but in no event higher than the maximum legal
rate permissible under applicable law, such interest to accrue from the date the
Company receives the Executive's statement for such fees and expenses through
the date of payment thereof; PROVIDED, HOWEVER, that in the event the resolution
of any such contest or dispute includes a finding denying, in total, the
Executive's claims in such contest or dispute, the Executive shall be required
to reimburse the Company, over a period of 12 months from the date of such
resolution, for all sums advanced to the Executive pursuant to this Section 6.

                  7. OPERATIVE EVENT. Notwithstanding any provision herein to
the contrary, no amounts shall be payable hereunder unless and until there is a
Change in Control at a time when the Executive is employed by the Company.

                  8. TERMINATION OF AGREEMENT. (a) This Agreement shall be
effective on the date hereof and shall continue until terminated by the Company
as provided in Section 8(b); PROVIDED, HOWEVER, that this Agreement shall
terminate in any event upon the earliest to occur of (i) termination of the
Executive's employment with the Company prior to a Change in Control, (ii) the
Executive's death and (iii) the date all obligations of the Company to make
payments or provide benefits to the Executive hereunder are satisfied in full.

                  (b) The Company shall have the right prior to a Change in
Control, in its sole discretion, pursuant to action by the Board, to approve the
termination of this Agreement, which termination shall not become effective
until the date fixed by the Board for such termination, which date shall be at
least 120 days after notice thereof is given by the Company to the Executive in
accordance with Section 11; PROVIDED, HOWEVER, that no such action shall be
taken by the Board during any period of time when the Board has knowledge that
any person has taken steps reasonably calculated to effect a Change in Control
until, in the opinion of the Board, such person has abandoned or terminated its
efforts to effect a Change in Control; and PROVIDED FURTHER, that in no event
shall this Agreement be terminated in the event of a Change in Control.

                  9. SCOPE OF AGREEMENT. Nothing in this Agreement shall be
deemed to entitle the Executive to continued employment with the Company or its
subsidiaries and, if the Executive's employment with the Company shall terminate
prior to a Change in Control, then the Executive shall have no further rights
under


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this Agreement; PROVIDED, HOWEVER, that any termination of the Executive's
employment following a Change in Control and prior to the end of the Termination
Period shall be subject to all of the provisions of this Agreement.

                  10.  SUCCESSORS; BINDING AGREEMENT.

                  (a) This Agreement shall not be terminated by any merger or
consolidation of the Company whereby the Company is or is not the surviving or
resulting corporation or as a result of any transfer of all or substantially all
of the assets of the Company. In the event of any such merger, consolidation or
transfer of assets, the provisions of this Agreement shall be binding upon the
surviving or resulting corporation or the person or entity to which such assets
are transferred.

                  (b) The Company agrees that concurrently with any merger,
consolidation or transfer of assets referred to in Section 10(a), it will cause
any successor or transferee unconditionally to assume, by written instrument
delivered to the Executive (or his beneficiary or estate), all of the
obligations of the Company hereunder. Failure of the Company to obtain such
assumption prior to or concurrent with the effectiveness of any such merger,
consolidation or transfer of assets shall be a breach of this Agreement and
shall entitle the Executive to compensation and other benefits from the Company
in the same amount and on the same terms as the Executive would be entitled
hereunder if the Executive's employment were terminated following a Change in
Control other than by reason of a Nonqualifying Termination. For purposes of
implementing the foregoing, the date on which any such merger, consolidation or
transfer becomes effective shall be deemed the Date of Termination.

                  (c) This Agreement shall inure to the benefit of and be
enforceable by the Executive's personal or legal representatives, executors,
administrators, successors, heirs, distributees, devisees and legatees. If the
Executive shall die while any amounts would be payable to the Executive
hereunder had the Executive continued to live, all such amounts, unless
otherwise provided herein, shall be paid in accordance with the terms of this
Agreement to such person or persons appointed in writing by the Executive to
receive such amounts or, if no person is so appointed, to the Executive's
estate.

                  11. NOTICES. (a) For purposes of this Agreement, all notices
and other communications required or permitted hereunder shall be in writing and
shall be deemed to have been duly given when delivered or five days after
deposit in the United States mail, certified and return receipt requested,
postage prepaid, addressed (1) if to the Executive, to Gary Ballard, and if to
the Company, to Aerial Communications, Inc., attention Vice President, Human
Resources, or (2) to such other address as


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either party may have furnished to the other in writing in accordance herewith,
except that notices of change of address shall be effective only upon receipt.

                  (b) A written notice of the Executive's Date of Termination by
the Company or the Executive, as the case may be, to the other, shall (i)
indicate the specific termination provision in this Agreement relied upon, (ii)
to the extent applicable, set forth in reasonable detail the facts and
circumstances claimed to provide a basis for termination of the Executive's
employment under the provision so indicated and (iii) specify the termination
date (which date shall be not less than 15 days after the giving of such
notice). The failure by the Executive or the Company to set forth in such notice
any fact or circumstance which contributes to a showing of Good Reason or Cause
shall not waive any right of the Executive or the Company hereunder or preclude
the Executive or the Company from asserting such fact or circumstance in
enforcing the Executive's or the Company's rights hereunder.

                  12. FULL SETTLEMENT; RESOLUTION OF DISPUTES. (a) The Company's
obligation to make any payments provided for in this Agreement and otherwise to
perform its obligations hereunder shall not be affected by any set-off,
counterclaim, recoupment, defense or other claim, right or action which the
Company may have against the Executive or others. In no event shall the
Executive be obligated to seek other employment or take any other action by way
of mitigation of the amounts payable to the Executive under any of the
provisions of this Agreement and such amounts shall not be reduced whether or
not the Executive obtains other employment.

                  (b) If there shall be any dispute between the Company and the
Executive in the event of any termination of the Executive's employment, then,
unless and until there is a final, nonappealable judgment by a court of
competent jurisdiction declaring that such termination was for Cause or without
Good Reason, or that the Company is not otherwise obligated to pay any amount or
provide any benefit to the Executive and his dependents or other beneficiaries,
as the case may be, under Sections 3(a) and 3(b), the Company shall pay all
amounts, and provide all benefits, to the Executive and his dependents or other
beneficiaries, as the case may be, that the Company would be required to pay or
provide pursuant to Sections 3(a) and 3(b) as though such termination were by
the Company without Cause or by the Executive with Good Reason; PROVIDED,
HOWEVER, that the Company shall not be required to pay any disputed amounts
pursuant to this Section 12(b) except upon receipt of an undertaking by or on
behalf of the Executive to repay all such amounts to which the Executive is
ultimately adjudged by such court not to be entitled.


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<PAGE>

                  13. EMPLOYMENT WITH AFFILIATES. Employment with the Company
for purposes of this Agreement shall include employment with any corporation or
other entity in which the Company has a direct or indirect ownership interest of
50% of more of the total combined voting power of the then outstanding
securities of such corporation or other entity entitled to vote generally in the
election of directors.

                  14. GOVERNING LAW; VALIDITY. The interpretation, construction
and performance of this Agreement shall be governed by and construed and
enforced in accordance with the internal laws of the State of Illinois without
regard to the principle of conflicts of laws. The invalidity or unenforceability
of any provision of this Agreement shall not affect the validity or
enforceability of any other provisions of this Agreement, which other provisions
shall remain in full force and effect.

                  15. COUNTERPARTS. This Agreement may be executed in two
counterparts, each of which shall be deemed to be an original and both of which
together shall constitute one and the same instrument.

                  16. MISCELLANEOUS. No provision of this Agreement may be
modified or waived unless such modification or waiver is agreed to in writing
and signed by the Executive and by a duly authorized officer of the Company. No
waiver by either party hereto at any time of any breach by the other party
hereto of, or compliance with, any condition or provision of this Agreement to
be performed by such other party shall be deemed a waiver of similar or
dissimilar provisions or conditions at the same or at any prior or subsequent
time. Failure by the Executive or the Company to insist upon strict compliance
with any provision of this Agreement or to assert any right the Executive or the
Company may have hereunder, including, without limitation, the right of the
Executive to terminate employment for Good Reason, shall not be deemed to be a
waiver of such provision or right or any other provision or right of this
Agreement. Except as otherwise expressly set forth in this Agreement, the rights
of, and benefits payable to, the Executive, his estate or his beneficiaries
pursuant to this Agreement are in addition to any rights of, or benefits payable
to, the Executive, his estate or his beneficiaries under any other employee
benefit plan or compensation program of the Company.


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<PAGE>

                  IN WITNESS WHEREOF, the Company has caused this Agreement to
be executed by a duly authorized officer of the Company and the Executive has
executed this Agreement as of the day and year first above written.


                                    AERIAL COMMUNICATIONS, INC.


                                    By:   /s/ Donald Warkentin
                                             --------------------------
                                             Donald Warkentin, President

                                    EXECUTIVE

                                          /s/ Gary F. Ballard
                                             -------------------------
                                                  Gary F. Ballard


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<PAGE>

                                                                       Exhibit A
                              Change in Control of
                        Telephone and Data Systems, Inc.


         For purposes of paragraph 1(d) of the Agreement, a "change in control"
with respect to Telephone and Data Systems, Inc. shall mean one of the
following:
                  (1) the acquisition by any individual, entity or group (a
         "Person"), including any "person" within the meaning of Section
         13(d)(3) or 14(d)(2) of the Exchange Act, of beneficial ownership
         within the meaning of Rule 13d-3 promulgated under the Exchange Act, of
         25% or more of the combined voting power of the then outstanding
         securities of Telephone and Data Systems, Inc., a Delaware corporation
         (the "Company") entitled to vote generally on matters (without regard
         to the election of directors) (the "Outstanding Voting Securities"),
         excluding, however, the following: (i) any acquisition directly from
         the Company or a corporation which owns directly or indirectly at least
         50% of the outstanding stock of the Company or the combined voting
         power of such outstanding stock or a corporation at least 50% of whose
         outstanding stock or the combined voting power of such outstanding
         stock is owned directly or indirectly by the Company (an "Affiliate")
         (excluding any acquisition resulting from the exercise of an exercise,
         conversion or exchange privilege, unless the security being so
         exercised, converted or exchanged was acquired directly from the
         Company or an Affiliate), (ii) any acquisition by the Company or an
         Affiliate, (iii) any acquisition by an employee benefit plan (or
         related trust) sponsored or maintained by the Company or an Affiliate,
         (iv) any acquisition by any corporation pursuant to a transaction which
         complies with clauses (i), (ii) and (iii) of subsection (3) of this
         Exhibit A, or (v) any acquisition by the following persons: (A) LeRoy
         T. Carlson or his spouse, (B) any child of LeRoy T. Carlson or the
         spouse of any such child, (C) any grandchild of LeRoy T. Carlson,
         including any child adopted by any child of LeRoy T. Carlson, or the
         spouse of any such grandchild, (D) the estate of any of the persons
         described in clauses (A)-(C), (E) any trust or similar arrangement
         (including any acquisition on behalf of such trust or similar
         arrangement by the trustees or similar persons) PROVIDED THAT all of
         the current beneficiaries of such trust or similar arrangement are
         persons described in clauses (A)-(C) or their lineal descendants, or
         (F) the voting trust which expires on June 30, 2009, or any successor
         to such voting trust, including the trustees of such voting trust on
         behalf of such voting trust (all such persons, collectively, the
         "Exempted Persons");


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<PAGE>

                  (2) individuals who, as of the effective date of the merger of
         Telephone and Data Systems, Inc., an Iowa corporation, into the
         Company, constitute the Board of Directors (the "Incumbent Board")
         cease for any reason to constitute at least a majority of such Board;
         PROVIDED THAT any individual who becomes a director of the Company
         subsequent to the effective date of the merger of Telephone and Data
         Systems, Inc., an Iowa corporation, into the Company, whose election,
         or nomination for election by the Company's stockholders, was approved
         by the vote of at least a majority of the directors then comprising the
         Incumbent Board shall be deemed a member of the Incumbent Board; and
         PROVIDED FURTHER, that any individual who was initially elected as a
         director of the Company as a result of an actual or threatened election
         contest, as such terms are used in Rule 14a-11 of Regulation 14A
         promulgated under the Exchange Act, or any other actual or threatened
         solicitation of proxies or consents by or on behalf of any Person other
         than the Board shall not be deemed a member of the Incumbent Board;

                  (3) the consummation of a reorganization, merger or
         consolidation or sale or other disposition of all or substantially all
         of the assets of the Company (a "Corporate Transaction"), excluding,
         however, a Corporate Transaction pursuant to which (i) all or
         substantially all of the individuals or entities who are the beneficial
         owners of the Outstanding Voting Securities immediately prior to such
         Corporate Transaction will beneficially own, directly or indirectly,
         more than 51% of the combined voting power of the outstanding
         securities of the corporation resulting from such Corporate Transaction
         (including, without limitation, a corporation which as a result of such
         transaction owns, either directly or indirectly, the Company or all or
         substantially all of the Company's assets) which are entitled to vote
         generally on matters (without regard to the election of directors), in
         substantially the same proportions relative to each other as the shares
         of Outstanding Voting Securities are owned immediately prior to such
         Corporate Transaction, (ii) no Person (other than the following
         Persons: (V) the Company or an Affiliate, (W) any employee benefit plan
         (or related trust) sponsored or maintained by the Company or an
         Affiliate, (X) the corporation resulting from such Corporate
         Transaction, (Y) the Exempted Persons, (Z) and any Person which
         beneficially owned, immediately prior to such Corporate Transaction,
         directly or indirectly, 25% or more of the Outstanding Voting
         Securities) will beneficially own, directly or indirectly, 25% or more
         of the combined voting power of the outstanding securities of such
         corporation entitled to vote


                                       A-2
<PAGE>

         generally on matters (without regard to the election of directors) and
         (iii) individuals who were members of the Incumbent Board will
         constitute at least a majority of the members of the board of
         directors of the corporation resulting from such Corporate
         Transaction; or

                  (4) the consummation of a plan of complete liquidation or
         dissolution of the Company.


                                       A-3
<PAGE>

                                                                       EXHIBIT B


                                 GENERAL RELEASE


                  This General Release (this "Release") is executed by _________
(the "Executive") pursuant to the Severance Agreement dated as of
______________, 1999 (the "Agreement") between the Executive and Aerial
Communications, Inc. (the "Company").

                  WHEREAS, the Executive's employment with the "Company" is
terminating;

                  WHEREAS, the Executive has had [21][45] days to consider the
form of this Release;

                  WHEREAS, the Company advised the Executive in writing to
consult with an attorney before signing this Release;

                  WHEREAS, the Executive acknowledges that the consideration to
be provided to the Executive under the Agreement is sufficient to support this
Release; and

                  WHEREAS, the Executive understands that the Company regards
the representations by the Executive in this Release as material and that the
Company is relying on such representations in paying amounts to the Executive
pursuant to the Agreement.

                  THE EXECUTIVE THEREFORE AGREES AS FOLLOWS:

                  1. The Executive's employment with the Company shall terminate
on ________, and the Executive shall receive the payments set forth in Section 3
of the Agreement in accordance with the terms and subject to the conditions
thereof.

                  2. The Executive, on behalf of the Executive and anyone
claiming through the Executive, hereby agrees not to sue the Company or
Telephone and Data Systems, Inc. ("TDS") or any division, subsidiary, affiliate
or other related entity of the Company or TDS (whether or not such entity is
wholly owned), or any of the past, present or future directors, officers,
administrators, trustees, fiduciaries, employees, agents, attorneys or
shareholders of the Company or TDS or any of such other entities, or the
predecessors, successors or assigns of any of them (hereinafter referred to as
the "Released Parties"), and agrees to release and discharge, fully, finally and
forever, the Released Parties from any and all claims, causes of action,
lawsuits, liabilities, debts, accounts, covenants, contracts, controversies,
agreements, promises, sums of money, damages, judgments and demands of any
nature whatsoever, in law or in equity, both known and unknown, asserted or not
asserted,


<PAGE>

foreseen or unforeseen, which the Executive ever had or may presently have
against any of the Released Parties arising from the beginning of time up to and
including the effective date of this Release, including, without limitation, all
matters in any way related to the Executive's employment by the Company or by
TDS or any of their affiliates, the terms and conditions thereof, any failure to
promote the Executive and the termination or cessation of the Executive's
employment with the Company or by TDS or any of their affiliates, and including,
without limitation, any and all claims arising under the Civil Rights Act of
1964, as amended, the Civil Rights Act of 1991, the Civil Rights Act of 1866,
the Age Discrimination in Employment Act, the Older Workers' Benefit Protection
Act, the Family and Medical Leave Act, the Americans With Disabilities Act, the
Executive Retirement Income Security Act of 1974, the Illinois Human Rights Act,
the Chicago or Cook County Human Rights Ordinance or any other federal, state,
local or foreign statute, regulation, ordinance or order, or pursuant to any
common law doctrine; provided, however, that nothing contained in this Release
shall apply to, or release the Company from, any obligation of the Company
contained in the Agreement. The consideration offered in the Agreement is
accepted by the Executive as being in full accord, satisfaction, compromise and
settlement of any and all claims or potential claims, and the Executive
expressly agrees that the Executive is not entitled to, and shall not receive,
any further recovery of any kind from the Company or any of the other Released
Parties, and that in the event of any further proceedings whatsoever based upon
any matter released herein, neither the Company nor any of the other Released
Parties shall have any further monetary or other obligation of any kind to the
Executive, including any obligation for any costs, expenses or attorneys' fees
incurred by or on behalf of the Executive. The Executive agrees that the
Executive has no present or future right to employment with the Company or any
of the other Released Parties.

                  3. The Executive expressly represents and warrants that the
Executive is the sole owner of the actual and alleged claims, demands, rights,
causes of action and other matters that are released herein; that the same have
not been transferred or assigned or caused to be transferred or assigned to any
other person, firm, corporation or other legal entity; and that the Executive
has the full right and power to grant, execute and deliver the general release,
undertakings and agreements contained herein.

                  4. ACKNOWLEDGMENT BY EXECUTIVE. BY EXECUTING THIS RELEASE, THE
EXECUTIVE EXPRESSLY ACKNOWLEDGES THAT THE EXECUTIVE HAS READ THIS RELEASE
CAREFULLY, THAT THE EXECUTIVE FULLY UNDERSTANDS ITS TERMS AND CONDITIONS, THAT
THE EXECUTIVE HAS BEEN ADVISED TO CONSULT WITH AN ATTORNEY PRIOR TO EXECUTING
THIS RELEASE, THAT THE EXECUTIVE HAS BEEN ADVISED THAT THE EXECUTIVE


<PAGE>

HAS [21][45] DAYS WITHIN WHICH TO DECIDE WHETHER OR NOT TO EXECUTE THIS RELEASE
AND THAT THE EXECUTIVE INTENDS TO BE LEGALLY BOUND BY IT. DURING A PERIOD OF
SEVEN DAYS FOLLOWING THE DATE OF THE EXECUTIVE'S EXECUTION OF THIS RELEASE, THE
EXECUTIVE SHALL HAVE THE RIGHT TO REVOKE THE RELEASE OF CLAIMS UNDER THE AGE
DISCRIMINATION IN EMPLOYMENT ACT BY SERVING WITHIN SUCH PERIOD WRITTEN NOTICE OF
REVOCATION. IF THE EXECUTIVE EXERCISES THE EXECUTIVE'S RIGHTS UNDER THE
PRECEDING SENTENCE, THE EXECUTIVE SHALL FORFEIT ALL AMOUNTS PAYABLE TO HIM
PURSUANT TO THE AGREEMENT.

                  5. The Agreement and this Release constitute the entire
understanding between the parties. The Executive has not relied on any oral
statements that are not included in the Agreement or this Release.

                  6. This Release shall be construed, interpreted and applied in
accordance with the internal laws of the State of Illinois without regard to the
principle of conflicts of laws.




                                                -----------------------------
                                                         [NAME]


                                                  Date:
                                                        ------------------------