<PAGE>

                                                                     Exhibit 3.8
                                                                     -----------

                                   iPCS, INC.

                          CERTIFICATE OF DESIGNATIONS
                                     OF THE
             SERIES A-2 CONVERTIBLE PARTICIPATING PREFERRED STOCK,
                           PAR VALUE $0.01 PER SHARE

                         Pursuant to Section 151 of the
                General Corporation Law of the State of Delaware

     iPCS, Inc., a Delaware corporation (the "Company"), acting pursuant to
                                              -------
Section 151 of the General Corporation Law of the State of Delaware (the
"DGCL"), does hereby submit the following Certificate of Designations of its
 ----
Series A-2 Convertible Participating Preferred Stock.

     FIRST:  The name of the Company is iPCS, Inc.

     SECOND:  By unanimous consent of the Board of Directors of the Company (the
"Board"), dated as of July 11, 2000, the following resolutions were duly
 -----
adopted:

     WHEREAS, the Certificate of Incorporation of the Company (the "Certificate
                                                                    -----------
of Incorporation"), authorizes 75,000,000 shares of preferred stock, issuable
----------------
from time to time in one or more series;

     WHEREAS, the Board is authorized, subject to certain limitations prescribed
by law and certain provisions of the Certificate of Incorporation, to establish
and fix the number of shares to be included in any series of preferred stock and
the designations, rights, preferences, powers, restrictions and limitations of
the shares of such series;

     WHEREAS, the Board established a series of preferred stock designated as
the Company's Series A-1 Convertible Participating Preferred Stock (the "Series
                                                                         ------
A-1 Preferred Stock"), and a series of preferred stock designated as Series A-2
-------------------
Convertible Participating Preferred Stock; and

     WHEREAS, the number of shares constituting such Series A-2 Convertible
Participating Preferred Stock shall be 40,000,000.

     NOW, THEREFORE, BE IT RESOLVED, that the series of preferred stock
designated as Series A-2 Convertible Participating Preferred Stock is hereby
authorized and established; and

     FURTHER, RESOLVED, that the Board does hereby fix and determine the
designations, rights, preferences, powers, restrictions and limitations of the
Series A-2 Convertible Participating Preferred Stock as follows:
<PAGE>

          1.  Ranking. The Series A-2 Convertible Participating Preferred Stock
              -------
(hereinafter in this Certificate of Designations called the "Series A-2
                                                             ----------
Preferred Stock") shall rank, with respect to dividends and distributions upon
---------------
the liquidation, winding-up and dissolution of the Company, (i) senior to the
Common Stock, par value $0.01 per share, of the Company (the "Common Stock") and
                                                              ------------
to each other class or series of stock of the Company (including any series of
preferred stock established after December 27, 2000 by the Board) the terms of
which do not expressly provide that it ranks senior to or on a parity with the
Series A-2 Preferred Stock as to dividends or distributions upon the
liquidation, winding-up or dissolution of the Company (collectively referred to
as "Junior Securities"); (ii) on a parity with the Series A-1 Preferred Stock of
    -----------------
the Company (together with the Series A-2 Preferred Stock, the "Preferred
                                                                ---------
Stock"), if any, and with any other class or series of stock of the Company, the
-----
terms of which expressly provide that such class or series will rank on a parity
with the Series A-2 Preferred Stock as to dividends or distributions upon the
liquidation, winding-up and dissolution of the Company (collectively referred to
as "Parity Securities"); and (iii) junior to any  class or series of stock of
    -----------------
the Company, the terms of which expressly provide that such class or series will
rank senior to the Series A-2 Preferred Stock as to dividends or distributions
upon liquidation, winding-up and dissolution of the Company (collectively
referred to as "Senior Securities").
                -----------------

          2.   Dividends.  (a) Dividends shall be payable on each share of
               ---------
Series A-2 Preferred Stock at a rate per annum equal to 7.5% of the Preferred
Liquidation Preference (as defined below) in effect as of the first day of each
semi-annual period or such shorter period with respect to which such dividend is
required to be paid.  Each share of Series A-2 Preferred Stock shall have a
"Stated Value" of $5.00.  Such dividends shall be payable only in additional
 ------------
shares of Series A-2 Preferred Stock with the value of each such additional
share being deemed to be equal to the Stated Value thereof. Dividends on each
share of Series A-2 Preferred Stock shall accrue on a daily basis and be
cumulative from the date of original issuance of such share of Series A-2
Preferred Stock (such date, the "Original Issue Date"). Such dividends shall be
                                 -------------------
payable, when, as and if declared by the Board, semi-annually on the fifteenth
day of January and July (each, a "Dividend Payment Date") in each year
                                  ---------------------
commencing with a payment on July 15, 2001 of dividends accrued from the
Original Issue Date.  Each such dividend shall be payable to the holders of
record of shares of Series A-2 Preferred Stock as they appear on the share
register of the Company on the corresponding Record Date.  As used herein, the
term "Record Date" means, with respect to the dividend payable on January 15 and
      -----------
July 15 of each year, the preceding December 31 and June 30, respectively.

          (b)  The amount of dividends payable for each full dividend period for
the Series A-2 Preferred Stock shall be computed by dividing the annual 7.5%
rate by two.  The amount of dividends payable for the initial dividend period,
or any period shorter than a full dividend period, on the Series A-2 Preferred
Stock shall be computed on the basis of twelve 30-day months and a 360-day year
and the actual number of days elapsed in the applicable period.

          (c)  Dividends on the Series A-2 Preferred Stock shall accrue whether
or not the Company has earnings or profits, whether or not there are funds
legally available for payment of such dividends and whether or not dividends are
declared.  Dividends shall accumulate and compound

                                       2
<PAGE>

semi-annually to the extent they are not paid on the Dividend Payment Date for
the period to which they relate. Dividends on account of arrears for accrued
dividends may be declared and paid at any time, without reference to any
Dividend Payment Date, to the holders of record of shares of Series A-2
Preferred Stock on such date, not exceeding 30 days preceding the payment date
thereof, as may be fixed by the Board. The Company shall take all actions
required or permitted under the General Corporation Law of Delaware to permit
the payment of dividends on the Series A-2 Preferred Stock.

          (d)  No dividends shall be declared or paid or set apart for payment
on the preferred  stock of any series ranking, as to dividends, on a parity with
the Series A-2 Preferred Stock for any period unless full cumulative dividends
have been or contemporaneously are declared and paid on the Series A-2 Preferred
Stock.  When dividends are not paid in full as aforesaid upon the shares of the
Series A-2 Preferred Stock and any other series of preferred stock ranking on a
parity as to dividends with the Series A-2 Preferred Stock, all dividends
declared upon shares of the Series A-2 Preferred Stock and any other series of
preferred stock ranking on a parity as to dividends with the Series A-2
Preferred Stock shall be declared pro rata so that the amount of dividends
declared per share on the Series A-2 Preferred Stock and such other series of
preferred stock shall in all cases bear to each other the same ratio that
accrued and unpaid dividends per share on the shares of the Series A-2 Preferred
Stock and such other series of preferred stock bear to each other.

          (e)  So long as any shares of the Series A-2 Preferred Stock are
outstanding, no dividend (other than a dividend in Common Stock or in any other
Junior Securities) shall be declared or paid or set aside for payment or other
distribution declared or made upon the Common Stock or upon any other Junior
Securities, nor shall any Common Stock or any other Junior Securities or Parity
Securities be redeemed, purchased or otherwise acquired for any consideration
(or any moneys be paid to or made available for a sinking fund for the
redemption of any such securities) by the Company (except by conversion into or
exchange for Junior Securities) unless, in each case, the full cumulative
dividends on all outstanding shares of the Series A-2 Preferred Stock shall have
been paid or declared and set aside for payment.

          (f) [Intentionally omitted]

          (g) In addition to dividends paid in accordance with Section 2(a)
above, when and if the Board shall declare a dividend or other distribution
payable with respect to the then outstanding shares of Common Stock, the holders
of the Series A-2 Preferred Stock shall be entitled to the amount of dividends
or other distributions per share as would be payable on the number of shares of
Common Stock into which each share of Series A-2 Preferred Stock could then be
converted pursuant to Section 5 hereof.

          (h)  (i) Subject to paragraph (ii) below, upon the first Change of
Control prior to  2005, the Company shall promptly issue to each holder of
Series A-2 Preferred Stock as a special dividend newly issued shares of Series
A-2 Preferred Stock with an aggregate Stated Value equal to the amount of all
unpaid dividends that would have been payable through July 12, 2005 to such
holder on the shares of Series A-2 Preferred Stock held by such holder
(including shares of Series

                                       3
<PAGE>

A-2 Preferred Stock that would have been held by such holder at the time of such
Change of Control assuming all dividends in arrears had been paid) at the time
of such Change of Control, assuming the Board declares and pays all dividends
payable on the Series A-2 Preferred Stock each semi-annual period (the "Special
                                                                        -------
Dividend"). Such issuance shall be in addition to, and not in lieu of, unpaid
--------
dividends payable from the date of such Change of Control on the Series A-2
Preferred Stock through July 12, 2005 and shall be made immediately prior to any
applicable Automatic Conversion (as defined below) resulting from the Change of
Control. In no event will the Special Dividend be paid more than once.

          (ii) In connection with a Change of Control arising pursuant to the
consummation of any Private Company Business Combination Transaction (as defined
below), the Blackstone (as defined in the Investment Agreement) designees, if
any, on the Board or, if Blackstone ceases to have the right to appoint any such
designees, Blackstone, pursuant to a notice delivered within 15 Business Days of
a request for such waiver made by the Company, shall be entitled in accordance
with Section 8.3(ii) of the Stockholders Agreement (as defined below) to waive
the application of the provisions of paragraph (i) above to such Change of
Control on behalf of all holders of the Series A-2 Preferred Stock.  In such
case, the provisions of paragraph (i) above shall apply to the next  Change of
Control prior to July 12, 2005.  Any such waiver by Blackstone shall be binding
on all holders of the Series A-2 Preferred Stock.

          3.  Liquidation Preference.
              ----------------------

          (a)  Upon any liquidation, dissolution or winding up of the Company,
whether voluntary or involuntary, before any distribution or payment shall be
made to the holders of any Junior Securities, each holder of Series A-2
Preferred Stock shall be entitled to be paid out of the remaining assets of the
Company legally available for distribution with respect to each share of Series
A-2 Preferred Stock an amount in cash equal to the greater of (i) the sum of (A)
the Stated Value plus (B) the aggregate Stated Value of any accrued but unpaid
dividends on such share of Series A-2 Preferred Stock (whether or not declared)
(such amount in this clause (i), the "Preferred Liquidation Preference") or (ii)
                                      --------------------------------
the amount such holder would have received with respect to such share of Series
A-2 Preferred Stock upon liquidation, dissolution or winding up had such holder
converted such share of Series A-2 Preferred Stock in accordance with the terms
of Section 5 into shares of Common Stock (such greater amount, the "Liquidation
                                                                    -----------
Preference").  If, upon any such liquidation, dissolution or winding up of the
----------
Company, the remaining assets of the Company available for distribution to its
stockholders shall be insufficient to pay the holders of shares of Series A-2
Preferred Stock the full Liquidation Preference and the holders of all Parity
Securities, including the Series A-1 Preferred Stock (if any), the full
liquidation preference thereof, the holders of shares of Series A-2 Preferred
Stock and any such other Parity Securities shall share ratably in any
distribution of the remaining assets of the Company in proportion to the
respective amounts which would otherwise be payable in respect of the shares
held by them upon such distribution if all amounts payable on or with respect to
such shares were paid in full.

                                       4
<PAGE>

          (b)  The value of any property not consisting of cash which is
distributed by the Company to the holders of the Series A-2 Preferred Stock
pursuant to Section 3(a) will equal the fair market value as determined by an
independent valuation firm selected by the Company and reasonably acceptable to
the members of the Board elected by the holders of the Series A-2 Preferred
Stock or, if there are no such members, the holders of a majority of the then
outstanding shares of Series A-2 Preferred Stock.

          4.  Voting Rights.
              -------------

          (a)  Each outstanding share of Series A-2 Preferred Stock shall
entitle the holder thereof to the number of votes equal to the number of shares
of Common Stock into which such share of Series A-2 Preferred Stock is
convertible (as adjusted from time to time pursuant to Section 5 hereof), at
each meeting of stockholders of the Company (and written actions of stockholders
in lieu of meetings) with respect to any and all matters on which the holders of
the Common Stock are entitled to vote.

          (b)  The holders of outstanding shares of Series A-2 Preferred Stock
and Series A-1 Preferred Stock, voting together as a separate class, shall be
entitled to elect two directors to the Board at a special meeting or annual
meeting of stockholders called for the purpose of electing directors or at any
special meeting of holders of Preferred Stock or by written consent, if the
aggregate number of shares of Preferred Stock outstanding is more than 4,545,455
(such number subject to adjustment as provided for in the Certificate of
Designations of the Series A-1 Preferred Stock); provided that, if the aggregate
number of shares of Preferred Stock that is outstanding on the applicable record
date is equal to or less than 4,545,455 (such number subject to adjustment  as
provided for in the Certificate of Designations of the Series A-1 Preferred
Stock) but not less than 2,272,727 (such number subject to adjustment as
provided for in the Certificate of Designations of the Series A-1 Preferred
Stock), the holders of outstanding shares of Series A-1 Preferred Stock and
Series A-2 Preferred Stock, voting together as a separate class, shall be
entitled to elect one director to the Board and, if the aggregate number of
shares of Series A-1 Preferred Stock and Series A-2 Preferred Stock that is
outstanding on the applicable record date is less than 2,272,727 (such number
subject to adjustment as provided for in the Certificate of Designations of the
Series A-1 Preferred Stock), the holders of outstanding shares of Series A-1
Preferred Stock and Series A-2 Preferred Stock, voting together as a separate
class, shall not be entitled to elect a director to the Board.

          (c)  Unless otherwise provided by law, the vote or written consent of
the holders of at least a majority of the then outstanding shares of Series A-2
Preferred Stock, voting together as a separate class, shall be necessary for
effecting or validating the following actions:

          (i)  any amendment, alteration or change (including by way of merger
               or consolidation) to the rights, preferences, privileges or
               powers of Series A-2 Preferred Stock in any manner that adversely
               affects the shares of such series;

                                       5
<PAGE>

          (ii)   any increase in the total number of authorized or issued shares
                 of Series A-2 Preferred Stock, other than the issuance of
                 additional shares of Series A-2 Preferred Stock pursuant to
                 Section 2 hereof, and any decrease in the authorized shares of
                 Series A-2 Preferred Stock;

          (iii)  any authorization, creation or issuance (including by way of
                 merger or consolidation) of any Senior Securities or Parity
                 Securities, or any obligation or security convertible into or
                 evidencing the right to purchase any Senior Securities or
                 Parity Securities, other than the issuance of any shares of
                 Series A-1 Preferred Stock pursuant to Section 2 of the
                 Certificate of Designations establishing the Series A-1
                 Preferred Stock;

          (iv)   any redemption, acquisition or other purchase of any share of
                 capital stock or other equity security of the Company or any of
                 its Subsidiaries (including warrants, options and other rights
                 to acquire such capital stock or other equity securities but
                 excluding shares of Preferred Stock), or any redemption,
                 acquisition or making of any payment with respect to any stock
                 appreciation rights, phantom stock plans or similar rights or
                 plans, except for (A) redemptions or repurchases of the capital
                 stock or other equity securities of any of its Subsidiaries (1)
                 that are held by the Company or any of its wholly-owned
                 Subsidiaries or (2) by any of its Subsidiaries if such
                 redemptions or repurchases are made pro rata with respect to
                 all holders of such Subsidiary's capital stock or other equity
                 interests and (B) redemptions, acquisitions or other purchases
                 of equity securities of the Company (including warrants,
                 options and other rights to acquire equity securities) owned by
                 current or former directors or employees of the Company for
                 consideration of up to $1,500,000 in the aggregate in any one
                 year and up to $7,000,000 in the aggregate;

          (v)    any amendment, repeal or alteration of the Company's
                 Certificate of Incorporation (including by merger or
                 consolidation) or bylaws in a manner that adversely affects the
                 holders of the Series A-2 Preferred Stock;

          (vi)   any voluntary liquidation, dissolution or winding up of the
                 Company; or

          (vii)  any arrangement or contract to do any of the foregoing, except
                 if such arrangement or contract expressly provides that the
                 undertaking of any of the foregoing is subject to prior
                 approval in accordance with this Section 4(c).

          (d)  (i)  The foregoing rights of holders of Preferred Stock to
approve any action as provided in subsections 4(b) and 4(c) may be exercised at
any annual or special meeting of stockholders or at a special meeting of holders
of the Preferred Stock or Series A-2 Preferred Stock, as applicable, held for
such purpose as hereinafter provided or at any adjournment thereof, or by the

                                       6
<PAGE>

written consent, delivered to the Secretary of the Company, of the holders of
the minimum number of shares required to take such action.

          So long as such right to vote continues (and unless such right has
been exercised by written consent of the holders of the minimum number of shares
required to take such action), the Chief Executive Officer of the Company may
call, and upon the written request of holders of record of at least 15% of the
outstanding shares of Preferred Stock or Series A-2 Preferred Stock, as
applicable, addressed to the Secretary of the Company at the principal office of
the Company, shall call, a special meeting of the holders of shares entitled to
vote as provided herein.  Such meeting shall be held within 30 days after
delivery of such request to the Secretary, at the place and on the notice
provided by law and in the bylaws of the Company for the holding of meetings of
stockholders.

          (ii) At any meeting (or in a written consent in lieu thereof) held for
the purpose of electing directors as provided in subsection 4(b) or to take any
action as provided in subsection 4(c), the presence in person or by proxy (or
the written consent) of the holders of a majority of the outstanding Preferred
Stock or Series A-2 Preferred Stock, as applicable, shall constitute a quorum of
the Preferred Stock or Series A-2 Preferred Stock, as applicable. For taking any
action as provided in subsections 4(b) and 4(c), each holder of outstanding
shares of Preferred Stock or Series A-2 Preferred Stock, as applicable, shall
have one vote for each share of such stock standing in his name on the share
register of the Company as of any record date fixed for such purpose or, if no
such date be fixed, at the close of business on the Business Day next preceding
the day on which notice is given, or if notice is waived, at the close of
business on the Business Day next preceding the day on which meeting is held;
provided, however, that shares of Preferred Stock held by the Company or any
Affiliate of the Company shall not be deemed to be outstanding for purposes of
taking any action as provided in this Section 4.  If the holders of the
outstanding shares of  Series A-2 Preferred Stock fail to constitute a quorum in
two duly called and notified consecutive meetings for the purpose of taking any
action set forth in subsection 4(c), such action or actions shall be deemed
approved by the holders of the Series A-2 Preferred Stock.

          Each director elected by the holders of outstanding shares of Series
A-1 Preferred Stock and Series A-2 Preferred Stock as provided in subsection
4(b) shall, unless his term shall expire earlier in accordance with the
provisions hereof, hold office for one year or until his successor, if any, is
elected and qualified. A vacancy in any directorship elected by the holders of
the Preferred Stock shall be filled only by vote or written consent of the
holders of a majority of the outstanding shares of Preferred Stock.  Any
director elected by the holders of the Preferred Stock may be removed from
office with or without cause by the vote or written consent of the holders of at
least a majority of the outstanding shares of Preferred Stock, at the time of
removal.  A special meeting of the holders of outstanding shares of Preferred
Stock may be called for any of the above purposes in accordance with the
procedures set forth in this subsection 4(d). The appropriate number of
directors elected by the holders of outstanding shares of Series A-1 Preferred
Stock and Series A-2 Preferred Stock shall resign upon the aggregate number of
outstanding shares of Preferred Stock falling below the applicable thresholds
provided under subsection 4(b).

                                       7
<PAGE>

          5.  Conversion Rights.
              -----------------

          (a)  Right to Convert.  The holders of the Series A-2 Preferred Stock
               ----------------
shall have conversion rights as follows (the "Conversion Rights"):
                                              -----------------

          (i)    Each share of Series A-2 Preferred Stock shall be convertible,
                 at the option of the holder thereof, at any time and from time
                 to time, subject to compliance with this Section 5, into fully
                 paid and nonassessable shares of Common Stock at the then
                 effective Conversion Rate (as defined below) (each such
                 conversion, an "Optional Conversion"). The "Conversion Rate"
                                 -------------------         ---------------
                 shall equal an amount determined by dividing (i) the Stated
                 Value plus the aggregate Stated Value of any accrued and unpaid
                 dividends (whether or not declared) on such share of Series A-2
                 Preferred Stock, by (ii) the Conversion Price (as defined
                 below) in effect at the time of conversion. The conversion
                 price at which shares of Common Stock shall be deliverable upon
                 conversion of Series A-2 Preferred Stock (the "Conversion
                                                                ----------
                 Price") shall initially be $5.00. Such initial Conversion Price
                 -----
                 shall be subject to adjustment as provided below.

          (ii)   In the event of a liquidation, dissolution or winding up of the
                 Company, whether voluntary or involuntary, as set forth in
                 Section 3 above, the rights of a holder to convert the Series
                 A-2 Preferred Stock shall terminate at the close of business on
                 the first full day preceding the date fixed for the payment of
                 any amounts distributable on liquidation to the holders of
                 Series A-2 Preferred Stock.

          (b)  Automatic Conversion.  Upon the earlier of:
               --------------------

          (i)    a Qualified Public Offering (as defined below);

          (ii)   the consummation of a Public Company Business Combination
                 Transaction which has resulted in a Change of Control (other
                 than pursuant to clause (vi) of the definition of Change of
                 Control); and

          (iii)  the consummation of a Private Company Business Combination
                 Transaction which has resulted in a Change of Control (other
                 than pursuant to clause (vi) of the definition of Change of
                 Control) and with respect to which Blackstone has not exercised
                 its rights in accordance with Section 2(h)(ii) hereof to waive
                 the application of the provisions of paragraph (i) of Section
                 2(h) to such Change of Control on behalf of all holders of the
                 Series A-2 Preferred Stock,

                                       8
<PAGE>

each share of Series A-2 Preferred Stock shall automatically convert (an
"Automatic Conversion") into fully paid and nonassessable shares of Common Stock
 --------------------
at the then effective Conversion Rate, subject to the prior receipt of all
applicable approvals or authorizations, if any, of any Governmental Entity
required in connection with any such Automatic Conversion.

          (c)  Fractional Shares.  No fractional shares of Common Stock shall be
               -----------------
issued upon conversion of the Series A-2 Preferred Stock.  In lieu of fractional
shares, the Company shall pay cash equal to such fraction multiplied by the then
effective Conversion Price.

          (d)  Mechanics of Conversion.
               -----------------------

          (i)    In order to convert shares of Series A-2 Preferred Stock into
                 shares of Common Stock, the holder shall surrender the
                 certificate or certificates for such shares of Series A-2
                 Preferred Stock at the office of the transfer agent (or at the
                 principal office of the Company if the Company serves as its
                 own transfer agent), together with, in the case of an Optional
                 Conversion, written notice that such holder elects to convert
                 all or any number of the shares represented by such certificate
                 or certificates. Such notice shall state the number of shares
                 of Series A-2 Preferred Stock which the holder seeks to
                 convert. In the event of an Automatic Conversion, (A) all
                 shares of Series A-2 Preferred Stock shall be deemed converted,
                 notwithstanding the failure of any holder thereof to surrender
                 the certificate or certificates corresponding to such shares
                 and (B) such holder shall be obligated to surrender such
                 certificate or certificates as a condition to delivery of the
                 certificate or certificates of shares of Common Stock into
                 which such shares of Series A-2 Preferred Stock were converted.
                 Certificates surrendered for conversion shall be endorsed or
                 accompanied by a written instrument or instruments of transfer,
                 in form reasonably satisfactory to the Company, duly executed
                 by the registered holder or his or its attorney duly authorized
                 by the registered holder in writing. The date of receipt of
                 such certificates and notice by the transfer agent or the
                 Company, complying with the requirements hereof, shall be the
                 conversion date ("Conversion Date"), except as to an Automatic
                                   ---------------
                 Conversion, the Conversion Date for which shall be the date of
                 occurrence of the event giving rise to the Automatic
                 Conversion. As soon as practicable after the Conversion Date,
                 the Company shall promptly issue and deliver to such holder at
                 its address in the Company's registry or at such other address
                 provided to the Company by such holder in writing a certificate
                 or certificates for the number of shares of Common Stock to
                 which such holder is entitled. Such conversion shall be deemed
                 to have been made at the close of business on the date of
                 receipt by the transfer agent or the Company of such
                 certificates and notice complying with the requirements hereof
                 with respect to the shares of Series A-2 Preferred Stock to be
                 converted, and the Person entitled to receive the shares of
                 Common Stock issuable upon such

                                       9
<PAGE>

                 conversion shall be treated for all purposes as the record
                 holder of such shares of Common Stock from and after such date.

          (ii)   The Company shall at all times during which the Series A-2
                 Preferred Stock shall be outstanding reserve and keep available
                 out of its authorized but unissued stock, for the purpose of
                 effecting the conversion of the Series A-2 Preferred Stock,
                 such number of its duly authorized shares of Common Stock as
                 shall from time to time be sufficient to effect the conversion
                 of all outstanding shares of Series A-2 Preferred Stock and all
                 shares of Series A-2 Preferred Stock required to be issued for
                 the payment of accrued dividends or which may be required to be
                 issued pursuant to Section 2(h) above. Before taking any action
                 which would cause an adjustment reducing the Conversion Price
                 below the then par value of the shares of Common Stock issuable
                 upon conversion of the Series A-2 Preferred Stock, the Company
                 will take any corporate action which may, in the opinion of its
                 counsel, be necessary in order that the Company may validly and
                 legally issue fully paid and nonassessable shares of Common
                 Stock at such adjusted Conversion Price. The Company shall
                 endeavor to comply with all federal or state law or applicable
                 governing rule or regulation of any national securities
                 exchange or automated quotation system regulating the offer and
                 delivery of shares of Common Stock upon conversion of the
                 Series A-2 Preferred Stock and shall list such shares of Common
                 Stock on each national securities exchange or automated
                 quotation system on which the Common Stock is listed, if any.

          (iii)  All shares of Series A-2 Preferred Stock which shall have been
                 surrendered for conversion as herein provided shall no longer
                 be deemed to be outstanding and all rights with respect to such
                 shares, including the rights, if any, to receive dividends,
                 notices and to vote, shall immediately cease and terminate on
                 the Conversion Date, except only the right of the holders
                 thereof to receive shares of Common Stock in exchange therefor,
                 and if applicable, cash in lieu of any fractional shares of
                 Common Stock. Any shares of Series A-2 Preferred Stock so
                 converted shall be retired and canceled and shall not be
                 reissued as Series A-2 Preferred Stock.

          (e)  Adjustments to Conversion Price for Diluting Issues.
               ---------------------------------------------------

          (i)    Special Definitions.  For purposes of this subsection 5(e), the
                 -------------------
                 following definitions shall apply:

                 (A)  "Option" shall mean rights, options or warrants to
                       ------
                      subscribe for, purchase or otherwise acquire Common Stock
                      or Convertible Securities, excluding (1) such rights,
                      options or warrants issued with respect to acquisitions by
                      the Company or a Subsidiary of assets or

                                       10
<PAGE>

                      interests in a business or entity in arm's length bona
                      fide transactions with an unaffiliated third party, or (2)
                      such rights, options or warrants issued to current or
                      former employees, directors or consultants of the Company
                      or any of its Subsidiaries as approved by the Board or
                      pursuant to plans or arrangements approved by the Board,
                      (3) warrants to acquire Common Stock issued by the Company
                      to Sprint Spectrum, L.P. pursuant to the Amended and
                      Restated Addendum III to the Sprint PCS Management
                      Agreement dated as of March 8, 2000 and (4) warrants to
                      acquire Common Stock issued by the Company prior to or on
                      the date of original issuance of the Series A-1 Preferred
                      Stock in connection with the High Yield Financing (all
                      such warrants under items (3) and (4), the "Excluded
                                                                  --------
                      Warrants").
                      --------

                 (B)  "Convertible Securities" shall mean any evidences of
                       ----------------------
                      indebtedness, shares or other securities directly or
                      indirectly convertible into or exchangeable for Common
                      Stock other than those described in clause (A) above,
                      excluding (1) such evidences of indebtedness, shares or
                      other securities issued with respect to acquisitions by
                      the Company or any of its Subsidiaries of assets or
                      interests in a business or entity in arm's length bona
                      fide transactions with an unaffiliated third party, (2)
                      such evidences of indebtedness, shares or other securities
                      issued to current or former employees, directors or
                      consultants of the Company or any of its Subsidiaries as
                      approved by the Board or pursuant to plans or arrangements
                      approved by the Board and (3) the Excluded Warrants.

                 (C)  "Additional Shares of Common Stock" shall mean all shares
                       ---------------------------------
                      of Common Stock issued (or, pursuant to subsection
                      5(e)(iii) below, deemed to be issued) by the Company after
                      the Original Issue Date, other than shares of Common Stock
                      issued or issuable:

                      (1)   as a dividend or distribution on Series A-1
                            Preferred Stock or Series A-2 Preferred Stock;

                      (2)  upon conversion of shares of Series A-1 Preferred
                           Stock or Series A-2 Preferred Stock;

                      (3)  to current or former employees, directors or
                           consultants of the Company or any of its
                           Subsidiaries, as approved by the Board or pursuant to
                           plans or arrangements approved by the Board;

                      (4)  with respect to acquisitions by the Company or any of
                           its Subsidiaries of assets or interests in a business
                           or entity in

                                       11
<PAGE>

                           arm's length bona fide transactions with an
                           unaffiliated third party; and

                      (5)  pursuant to the Excluded Warrants.

                 (D)  "Rights to Acquire Common Stock" (or "Rights") shall mean
                       ------------------------------       ------
                      all rights issued by the Company to acquire Common Stock
                      whether by exercise of a warrant (other than the Excluded
                      Warrants), option or similar call, or conversion of any
                      existing instruments, in either case for consideration
                      fixed, in amount or by formula, as of the date of
                      issuance, excluding rights issued pursuant to any
                      shareholder rights plan of the Company, such rights issued
                      to current or former employees, directors or consultants
                      of the Company or any of its Subsidiaries as approved by
                      the Board or pursuant to plans or arrangements approved by
                      the Board and any such rights issued with respect to
                      acquisitions by the Company or any of its Subsidiaries of
                      assets or interests in a business or entity in arm's
                      length bona fide transactions with unaffiliated third
                      parties.

          (ii)   No Adjustment of Conversion Price.  Notwithstanding anything in
                 ---------------------------------
                 this Certificate of Designations to the contrary, no adjustment
                 in the Conversion Price shall be made by any means under this
                 subsection 5(e), unless the consideration per share (determined
                 pursuant to subsection 5(e)(v) below) received by the Company
                 for an Additional Share of Common Stock issued or deemed to be
                 issued by the Company is less than $5.00 per share, subject to
                 adjustment pursuant to this subsection 5(e), and subsections
                 5(f), (g), (i) and (j) below or, if prior to such issuance, the
                 Company receives written notice from the holders of at least a
                 majority of the then outstanding shares of Series A-2 Preferred
                 Stock, voting together as a separate class, agreeing that no
                 such adjustment shall be made as a result of such issuance of
                 Additional Shares of Common Stock.

          (iii)  Issuance of Securities Deemed Issuance of Additional Shares of
                 --------------------------------------------------------------
                 Common Stock. If the Company at any time or from time to time
                 ------------
                 after the Original Issue Date issues any Options or Convertible
                 Securities or Rights to Acquire Common Stock, then the maximum
                 number of shares of Common Stock (as set forth in the
                 instrument relating thereto without regard to any provision
                 contained therein for a subsequent adjustment of such number)
                 issuable upon the exercise of such Options or Rights to Acquire
                 Common Stock or, in the case of Convertible Securities,
                 issuable upon the conversion or exchange of such Convertible
                 Securities, in each case, on the date of their issuance, shall
                 be deemed to be the number of Additional Shares of Common Stock
                 issued as of the time of such issue; provided, however, that
                 Additional Shares of



                                       12
<PAGE>

               Common Stock shall not be deemed to have been issued unless the
               consideration per share (determined pursuant to subsection
               5(e)(v) hereof) that would be received by the Company for such
               Additional Shares of Common Stock upon such exercise, conversion
               or exchange would be less than $5.00 per share, subject to
               adjustment pursuant to this subsection 5(e) and subsections 5(f),
               (g), (i) and (j) below, and provided, further, that in any such
               case:

               (A)  no further adjustment in the Conversion Price shall be made
                    upon the subsequent issuance of shares of Common Stock upon
                    the exercise of such Options or Rights to Acquire Common
                    Stock or upon the conversion or exchange of such Convertible
                    Securities;

               (B)  upon the expiration or termination of any unexercised
                    Option, Right to Acquire Common Stock or Convertible
                    Security, the Conversion Price shall be adjusted immediately
                    to reflect the applicable Conversion Price which would have
                    been in effect had such Option, Right to Acquire Common
                    Stock or Convertible Security (to the extent outstanding
                    immediately prior to such expiration or termination) never
                    been issued;

               (C)  if with respect to any Option, Right to Acquire Common Stock
                    or Convertible Security, there shall have been an increase
                    or decrease, with the passage of time or otherwise, in the
                    consideration (determined pursuant to subsection 5(e)(v)
                    below) payable upon the exercise, conversion or exchange
                    thereof, then the Conversion Price then in effect shall be
                    readjusted by (x) treating the Additional Shares of Common
                    Stock, if any, actually issued or issuable pursuant to the
                    previous exercise of such Option, Right to Acquire Common
                    Stock or Convertible Security as having been issued or
                    issuable for the consideration actually received and
                    receivable therefor and (y) treating any Option, Right to
                    Acquire Common Stock or Convertible Security which remains
                    outstanding as being subject to exercise, conversion or
                    exchange on the basis of such revised consideration payable
                    as shall be in effect at such time; and

               (D)  in the event of any change in the number of shares of Common
                    Stock issuable upon the exercise, conversion or exchange of
                    any Option, Right or Convertible Security, including, but
                    not limited to, a change resulting from the anti-dilution
                    provisions thereof, the Conversion Price then in effect
                    shall forthwith be readjusted to such Conversion Price as
                    would have been obtained had the Conversion Price adjustment
                    that was originally made upon the issuance of such

                                       13
<PAGE>

                    Option, Right to Acquire Common Stock or Convertible
                    Security which were not exercised, converted or exchanged
                    prior to such change been made upon the basis of such
                    change, but no further adjustment shall be made for the
                    actual issuance of Common Stock upon the exercise or
                    conversion of any such Option, Right to Acquire Common Stock
                    or Convertible Security.

          (iv)   Adjustment of Conversion Price upon Issuance of Additional
                 ----------------------------------------------------------
                 Shares of Common Stock. If the Company shall at any time after
                 ----------------------
                 the Original Issue Date issue Additional Shares of Common Stock
                 (including Additional Shares of Common Stock deemed to be
                 issued pursuant to subsection 5(e)(iii), but excluding shares
                 issued as a dividend or distribution as provided in subsection
                 5(g) or upon a stock split or combination as provided in
                 subsection 5(f)), without consideration, or for a consideration
                 per share less than $5.00 per share, subject to adjustment
                 pursuant to this subsection 5(e) and subsections 5(f), (g), (i)
                 and (j), then and in such event, the Conversion Price shall be
                 reduced, concurrently with such issuance, to a price
                 (calculated to the nearest cent) determined by multiplying such
                 Conversion Price then in effect by a fraction, the numerator of
                 which shall be the sum of (A) the number of shares of Common
                 Stock outstanding, on a fully diluted basis, immediately prior
                 to such issuance plus (B) the number of shares of Common Stock
                 which the aggregate consideration received by the Company for
                 the total number of Additional Shares of Common Stock so issued
                 or deemed to be issued would purchase at $5.00 per share,
                 subject to adjustment pursuant to this subsection 5(e) and
                 subsections 5(f), (g), (i) and (j) , and the denominator of
                 which shall be the sum of (1) the number of shares of Common
                 Stock outstanding, on a fully diluted basis, immediately prior
                 to such issuance plus (2) the number of such Additional Shares
                 of Common Stock so issued or deemed to be issued.

                 Notwithstanding the foregoing, the applicable Conversion Price
                 shall not be reduced if the amount of such reduction would be
                 an amount less than $.01, but any such amount shall be carried
                 forward and reduction with respect thereto made at the time of
                 and together with any subsequent reduction which, together with
                 such amount and any other amount or amounts so carried forward,
                 shall aggregate $.01 or more.

          (v)    Determination of Value of Consideration.  For purposes of this
                 ---------------------------------------
                 subsection 5(e), the value of the consideration received by the
                 Company for the issuance of any Additional Shares of Common
                 Stock shall be computed as follows:

                 (A)  Cash and Property.  Such consideration shall:
                      -----------------

                                       14
<PAGE>

                      (1)  insofar as it consists of cash, be computed at the
                           aggregate of cash received and the net present value
                           of cash receivable (utilizing a discount rate of 5%
                           per annum) by the Company, excluding amounts paid or
                           payable for accrued interest or accrued dividends;

                      (2)  insofar as it consists of property other than cash
                           (subject to clause (3) below), be computed at the
                           fair market value thereof at the time of such issue,
                           as determined in good faith by the Board;

                      (3)  insofar as it consists of securities, be computed as
                           follows: (x) if traded on a securities exchange or
                           quotation system, based on the average of the closing
                           prices of the securities on such exchange or
                           quotation system over the 30 trading day period
                           ending on the trading day immediately preceding the
                           day the computation is being made, (y) if traded
                           over-the-counter, based on the average of the closing
                           bid or sale prices (whichever is applicable) over the
                           45 trading day period ending on the trading day
                           immediately preceding the day the computation is
                           being made, and (z) the securities are not traded as
                           set forth in (x) or (y) above, the fair market value
                           thereof at the time of such issue, as determined in
                           good faith by the Board; and

                      (4)  in the event Additional Shares of Common Stock are
                           issued together with other shares or securities or
                           other assets of the Company for consideration which
                           covers both, be the proportion of such consideration
                           so received, computed as provided in clauses (1)
                           through (3) above, as determined in good faith by the
                           Board.

                 (B)  Options, Rights and Convertible Securities.  The
                      ------------------------------------------
                      consideration per share received by the Company for
                      Additional Shares of Common Stock deemed to have been
                      issued pursuant to subsection 5(e)(iii), relating to
                      Options, Rights to Acquire Common Stock and Convertible
                      Securities, shall be determined by dividing

                      (1)  the total amount, if any, received or receivable by
                           the Company as consideration for the issuance of such
                           Options, Rights or Convertible Securities, plus the
                           aggregate amount of additional consideration expected
                           to be payable to the Company (as determined in good
                           faith by the Board) upon the

                                       15
<PAGE>

                           exercise of such Options or Rights to Acquire Common
                           Stock or upon the conversion or exchange of such
                           Convertible Securities, by

                      (2)  the maximum number of shares of Common Stock issuable
                           upon the exercise of such Options or Rights to
                           Acquire Common Stock or upon the conversion or
                           exchange of such Convertible Securities.

          (f)  Adjustment for Stock Splits and Combinations.  If the Company
               --------------------------------------------
shall at any time or from time to time after the Original Issue Date effect a
subdivision of the outstanding Common Stock, the Conversion Price then in effect
immediately before that subdivision shall be proportionately decreased.  If the
Company shall at any time or from time to time after the Original Issue Date
combine the outstanding shares of Common Stock, the Conversion Price then in
effect immediately before the combination shall be proportionately increased.
Any adjustment under this paragraph shall become effective at the time the
subdivision or combination becomes effective.

          (g)  Adjustment for Certain Dividends and Distributions.  In the event
               --------------------------------------------------
the Company at any time or from time to time after the Original Issue Date shall
make or issue a dividend or other distribution payable in Additional Shares of
Common Stock, then and in each such event the Conversion Price then in effect
shall be decreased as of the time of such issuance, by multiplying such
Conversion Price by a fraction, the numerator of which shall be the total number
of shares of Common Stock outstanding on a fully diluted basis, immediately
prior to such issuance and the denominator of which shall be the total number of
shares of Common Stock outstanding, on a fully diluted basis,  immediately prior
to such issuance plus the number of such Additional Shares of Common Stock
issued in payment of such dividend or distribution; provided that no such
adjustment shall be made if the holders of the Series A-2 Preferred Stock
receive such dividend or distribution.  For purposes of this subsection (g), the
number of shares of Common Stock at any time outstanding shall not include
shares held in the treasury of the Company.  The Company will not pay any
dividend or make any distribution on shares of Common Stock held in the treasury
of the Company.

          (h)  Adjustments for Other Dividends and Distributions.  In the event
               -------------------------------------------------
the Company at any time, or from time to time, after the Original Issue Date
shall make or issue a dividend or other distribution payable in securities of
the Company (other than shares of Common Stock) or other assets or properties,
then, and in each such event, provision shall be made so that the holders of
shares of the Series A-2 Preferred Stock (whether then outstanding or thereafter
issued) shall receive upon conversion thereof, in addition to the number of
shares of Common Stock receivable thereupon, the amount of securities of the
Company or such other assets or properties that they would have received had
their Series A-2 Preferred Stock been converted into Common Stock on the date of
such event and had thereafter, during the period from the date of such event to
and including the Conversion Date, retained such securities receivable by them
as aforesaid during such period giving application to all adjustments called for
during such period, under this paragraph with respect to the

                                       16
<PAGE>

rights of the holders of the Series A-2 Preferred Stock; provided that no such
adjustment shall be made if the holders of the Series A-2 Preferred Stock
receive such dividend or distribution.

          (i)  Adjustment for Reclassification, Exchange or Substitution.  If
               ---------------------------------------------------------
the Common Stock issuable upon the conversion of the Series A-2 Preferred Stock
shall be changed into the same or a different number of shares of any class or
classes of stock and other securities and property, whether by capital
reorganization, reclassification, or otherwise (other than a subdivision or
combination of shares, stock dividend, merger, consolidation, asset sale or
other transaction provided for elsewhere in this Section 5), then and in each
such event the holder of each share of Series A-2 Preferred Stock (whether then
outstanding or thereafter issued) shall have the right thereafter to convert
such share into the kind and amount of shares of stock and other securities and
property receivable upon such reorganization, reclassification or other change,
by holders of the number of shares of Common Stock into which all such shares of
Series A-2 Preferred Stock might have been converted immediately prior to such
reorganization, reclassification, or change, all subject to further adjustment
as provided herein or with respect to such other securities or property by the
terms thereof.  In case of such change (other than a subdivision or combination
of shares, stock dividend, merger, consolidation, asset sale or other
transaction provided for elsewhere in this Section 5), appropriate adjustment
will be made in the application of the provisions of this Section 5 with respect
to the rights of the holders of Series A-2 Preferred Stock after the capital
reorganization, reclassification or other such change to the end that the
provisions of this Section 5 (including adjustment of the Conversion Price then
in effect and the number of shares issuable upon conversion of the Series A-2
Preferred Stock) will be applicable after that event and be as nearly equivalent
as practicable.

          (j)  Reorganizations, Mergers, Consolidations or Asset Sales.  If at
               -------------------------------------------------------
any time after the Original Issue Date there is a merger, consolidation,
recapitalization, sale of all or substantially all of the Company's assets,
reorganization or other business combination transaction, in each case involving
the Common Stock (collectively, a "Capital Reorganization") (other than a
                                   ----------------------
recapitalization, subdivision, combination, reclassification, exchange or
substitution of shares or other transaction provided for elsewhere in this
Section 5), as part of such Capital Reorganization, provision will be made so
that the holders of Series A-2 Preferred Stock (whether then outstanding or
thereafter issued) will thereafter be entitled to receive upon conversion of the
Series A-2 Preferred Stock the number of shares of stock or other securities or
property of the Company to which a holder of the number of shares of Common
Stock deliverable upon conversion would have been entitled on such Capital
Reorganization, subject to adjustment in respect to such stock or securities by
the terms thereof.  In case of any such Capital Reorganization (other than a
recapitalization, subdivision, combination, reclassification, exchange or
substitution of shares or other transaction provided for elsewhere in this
Section 5), appropriate adjustment will be made in the application of the
provisions of this Section 5 with respect to the rights of the holders of Series
A-2 Preferred Stock after the Capital Reorganization to the end that the
provisions of this Section 5 (including adjustment of the Conversion Price then
in effect and the number of shares issuable upon conversion of the Series A-2
Preferred Stock) will be applicable after that event and be as nearly equivalent
as practicable.  In the event that the Company is not the surviving entity of
any such Capital Reorganization, and in the event that such Capital
Reorganization does not result in an Automatic Conversion, each share of

                                       17
<PAGE>

Series A-2 Preferred Stock shall become shares of preferred stock of such
surviving entity, with the same powers, rights and preferences as provided
herein.

          (k)  No Effect on Dividends.  Nothing in this Section 5 shall affect
               ----------------------
the continued accrual of dividends on the Series A-2 Preferred Stock in
accordance with the terms of this Certificate of Designations.

          (l)  Certificate as to Adjustments.  Upon the occurrence of each
               -----------------------------
adjustment or readjustment of the Conversion Price pursuant to this Section 5,
the Company at its expense shall promptly compute such adjustment or
readjustment in accordance with the terms hereof and furnish by certified or
registered mail to each holder, if any, of Series A-2 Preferred Stock
outstanding at such holder's address shown in the Company's registry, a
certificate setting forth such adjustment or readjustment and showing in
reasonable detail the facts upon which such adjustment or readjustment is based
and shall file a copy of such certificate with its corporate records. Any
objection to such computation contained in any such certificate shall be made in
writing and shall be sent by mail to the Company at 1900 E. Golf Road, Suite
900, Schaumburg, Illinois 60173, or such other address as shall be set forth in
the certificate containing such computation, within 10 Business Days of receipt
of such computation by the applicable holder or shall otherwise be deemed to be
waived; provided that no such waiver shall take effect if all relevant
information required to make a complete evaluation of the computation was not
provided in the notice. The Company shall also, upon the reasonable written
request of any holder of Series A-2 Preferred Stock, furnish or cause to be
furnished to such holder a similar certificate setting forth (i) such
adjustments and readjustments, (ii) the Conversion Price then in effect, and
(iii) the number of shares of Common Stock and the amount, if any, of other
property which then would be received upon the conversion of Series A-2
Preferred Stock. Despite such adjustment or readjustment, the form of each or
all Series A-2 Preferred Stock certificates, if the same shall reflect the
initial or any subsequent Conversion Price, need not be changed in order for the
adjustments or readjustments to be valid in accordance with the provisions of
this Certificate of Designations, which shall control.

          (m)  Transfer Taxes.  The Company shall pay any and all documentary,
               --------------
stamp, issue or transfer taxes, and any other similar taxes payable in respect
of the issue or delivery of shares of Common Stock upon conversion of shares of
Series A-2 Preferred Stock pursuant hereto; provided, however, that the Company
shall not be required to pay any tax which may be payable in respect of any
transfer involved in the issue or delivery of shares of Common Stock in a name
other than that of the holder of the shares of Series A-2 Preferred Stock to be
converted and no such issue or delivery shall be made unless and until the
person requesting such issue or delivery has paid to the Company the amount of
any such tax or has established, to the reasonable satisfaction of the Company,
that such tax has been paid.

          (n)  Definition of Common Stock.  For purposes of this Section 5,
               --------------------------
"Common Stock" includes any stock of any class of the Company which has no
stated preference in respect of dividends or of amounts payable in the event of
any voluntary or involuntary liquidation, dissolution or winding-up of the
Company and which is not by its terms subject to redemption by the Company.

                                       18
<PAGE>

However, subject to the provision of subsection 5(j), shares issuable on
conversion of shares of the Series A-2 Preferred Stock shall include only shares
of the class designated as Common Stock of the Company on the Original Issue
Date, subject to adjustment in accordance with subsections 5(e) through 5(j)
above; provided that, if at any time there shall be more than one resulting
class, the shares of each such class then so issuable shall be substantially in
the proportion which the total number of shares of such class resulting from all
such reclassifications bears to the total number of shares of all such classes
resulting from all such reclassifications.

          (o)  No Adjustment Less Than Par Value.  No adjustment in the
               ---------------------------------
Conversion Price shall reduce the Conversion Price below the then par value of
the Common Stock.

          6.  Redemption.  (a)  The Company shall redeem all then outstanding
              ----------
shares of Series A-2 Preferred Stock on July 12, 2011 (the "Redemption Date")
                                                            ---------------
for a cash amount per share of Series A-2 Preferred Stock equal to the Preferred
Liquidation Preference.

          (b)  The Company shall take such actions as are necessary (including,
without limitation, conducting an appraisal of the assets and liabilities of the
Company, if necessary) in order to establish the availability of funds legally
available for any required redemption pursuant to Section 6(a) hereof.

          7.  Notice.  In the event that the Company takes any action which
              ------
would require an adjustment, pursuant to subsections 5(e) through 5(j) above
that involves the setting of a record date, then the Company shall cause to be
filed at its principal office or at the office of the transfer agent of the
Series A-2 Preferred Stock, and shall cause to be mailed to the holders of the
Series A-2 Preferred Stock at their last addresses as shown on the records of
the Company, or such transfer agent, at least 10 days prior to the applicable
record date a notice stating the record date for the applicable adjustment.

          8.  Headings of Subdivisions.  The headings of the various
              ------------------------
subdivisions hereof are for convenience of reference only and shall not affect
the interpretation of any of the provisions hereof.

          9.  Severability of Provisions.  If any of the voting powers,
              --------------------------
preferences and relative, participating, optional and other special rights of
the holders of the Series A-2 Preferred Stock and qualifications, limitations
and restrictions thereof set forth herein is invalid, unlawful or incapable of
being enforced by reason of any rule of law or public policy, all other voting
powers, preferences and relative, participating, optional and other special
rights of  holders of the Series A-2 Preferred Stock and qualifications,
limitations and restrictions thereof set forth herein which can be given effect
without the invalid, unlawful or unenforceable voting powers, preferences and
relative, participating, optional and other special rights of Series A-2
Preferred Stock and qualifications, limitations and restrictions thereof shall,
nevertheless, remain in full force and effect, and no voting powers, preferences
and relative, participating, optional or other special rights of Series A-2
Preferred Stock and qualifications, limitations and restrictions thereof herein
set forth shall be

                                       19
<PAGE>

deemed dependent upon any other such voting powers, preferences and relative,
participating, optional or other special rights of Series A-2 Preferred Stock
and qualifications, limitations and restrictions thereof unless so expressed
herein.

          10.  Mutilated or Missing Series A-2 Preferred Stock Certificates.  If
               ------------------------------------------------------------
any of the Series A-2 Preferred Stock certificates shall be mutilated, lost,
stolen or destroyed, the Company shall issue, in exchange and in substitution
for and upon cancellation of the mutilated Series A-2 Preferred Stock
certificate, or in lieu of and substitution for the Series A-2 Preferred Stock
certificate mutilated, lost, stolen or destroyed, a new Series A-2 Preferred
Stock certificate of like tenor and representing an equivalent amount of shares
of Series A-2 Preferred Stock, but only upon receipt of evidence of such
mutilation, loss, theft or destruction of such Series A-2 Preferred Stock
certificate and indemnity, in each case  reasonably satisfactory to the Company.

          11.  Certain Definitions.  As used in this Certificate of
               -------------------
Designations, the following terms shall have the following meanings (with terms
defined in the singular having comparable meanings when used in the plural and
vice versa), unless the context otherwise requires:

          "Affiliate" shall mean, with respect to any Person, any other Person
     which directly or indirectly controls or is controlled by or is under
     common control with such Person.  As used in this definition, "control"
     (including its correlative meanings, "controlled by" and "under common
     control with") shall mean possession, directly or indirectly, of power to
     direct or cause the direction of management or policies (whether through
     ownership of securities or partnership or other ownership interests, by
     contract or otherwise).

          "Business Combination Transaction" shall mean any merger,
     consolidation, reorganization, recapitalization, spin-off, liquidation,
     joint venture, partnership, tender or exchange offer or asset or stock
     purchase, sale or exchange or any similar transaction or any series or
     combination of related transactions pursuant to any agreement between the
     Company or any of its Subsidiaries, on the one hand, and any other Person,
     on the other.

          "Business Day" shall mean any day except a Saturday, a Sunday, or
     other day on which commercial banks in the State of New York or Illinois
     are authorized or required by law or executive order to close.

          "Change of Control" shall mean the happening of any of the following
     events:

     (i)    any Person or "group" (as defined in Section 13(d) of the Exchange
            Act), excluding a Person who is Current Stockholder, is or becomes
            the beneficial owner (as defined in Rules 13d-3 and 13d-5 under the
            Exchange Act, except that such Person shall be deemed to have
            "beneficial ownership" of all shares that any such Person has the
            right to acquire, whether such right is exercisable immediately or
            only after the passage of time), directly or indirectly, of more
            than 50% of the aggregate voting

                                       20
<PAGE>

            power of securities (including the Common Stock) of the Company or
            of Geneseo Communications, Inc. or Cambridge Telcom, Inc.;

     (ii)   Geneseo Communications, Inc., Cambridge Telcom, Inc. and their
            Affiliates as of the date hereof (the "Controlling Shareholders")
            collectively do not beneficially own more shares of voting
            securities of the Company than any other Person or "group" (as
            defined in Section 13(d) of the Exchange Act) (other than Blackstone
            (as defined in the Investment Agreement) and its Affiliates), which
            Person or group beneficially owns more than 35% of such voting
            securities;

     (iii)  any transaction occurs that results in the stockholders of the
            Company or of Geneseo Communications, Inc. or Cambridge Telcom, Inc.
            immediately prior to such transaction being the holders of less than
            50% of the aggregate voting power of securities of the resulting
            company immediately after such transaction;

     (iv)   a majority of the members of the Board consists of individuals who
            are neither (A) members of the Board on the date hereof or appointed
            by Blackstone, (B) full time employees or directors of a Current
            Stockholder, but only if such employee or director is not an
            Affiliate of, associated with or employed by a Person (or an
            Affiliate thereof) who at such time is a stockholder of the Company
            but is not a Current Stockholder or (C) an individual who was
            requested to be placed on the Board by a Current Stockholder, but
            only if such individual is not an Affiliate of, associated with or
            employed by a Person (or an Affiliate thereof) who at such time is a
            stockholder of the Company but is not a Current Stockholder;

     (v)    a merger, consolidation, sale of assets or other similar business
            combination transaction is consummated and, as a direct result,
            Timothy M. Yager ceases to be the Chief Executive Officer of the
            Company or its successor; or

     (vi)   any liquidation, dissolution or winding up of the Company or any
            dividend or other distribution to stockholders of the Company of all
            or in excess of 50% of the Fair Market Value (as determined in
            accordance with Section 5.1(b) of the Stockholders Agreement) of the
            assets of the Company and its Subsidiaries, taken as a whole, in any
            transaction or series of related transactions..

            "Current Stockholder" shall mean (i) a Person who is a stockholder
     of the Company as of the date hereof and (ii) Affiliates of such Person as
     of the date hereof.

            "Exchange Act" shall mean the Securities Exchange Act of 1934, as
     amended.

            "Governmental Entity" means any court, department, body, board,
     bureau, administrative agency or commission and other governmental
     authority or instrumentality.

                                       21
<PAGE>

            "High Yield Financing" shall mean the 14% senior discount notes of
     the Company due 2010 and the accompanying warrants exercisable for Common
     Stock issued by the Company as described in the Company's offering
     memorandum dated July 10, 2000.

            "Investment Agreement" shall mean the Investment Agreement, dated as
     of July 12, 2000, among the Company and the Purchasers (as defined
     therein).

            "Person" shall mean an individual, corporation, limited liability
     company, association, partnership, group (as defined in Section 13(d)(3) of
     the Exchange Act), trust, joint venture, business trust or unincorporated
     organization, or a government or any agency or political subdivision
     thereof or other entity of any nature whatsoever.

            "Private Company" shall mean any Person other than a Public Company.

            "Private Company Business Combination Transaction" means any
     Business Combination Transaction between the Company or any of its
     Subsidiaries and a Private Company or any of its Subsidiaries.

            "Public Company" shall mean a Person whose common stock or
     equivalent thereof is listed on the New York Stock Exchange, Inc. or quoted
     on the Nasdaq National Market and of which (i) the aggregate market value
     of such common stock exceeds $200,000,000, (ii) the aggregate market value
     of such common stock or equivalent thereof held by Persons who are not
     Affiliates, or any officer, director, employee or stockholder holding of
     record or beneficially more than 5% of any class of voting securities of
     such Person or any Subsidiary of any Person or any individual related by
     blood, marriage or adoption to such individual or any entity in which such
     Person or individual owns a greater than 5% beneficial interest of the
     Company exceeds $50 million and (iii) it is reasonably anticipated that
     such common stock will continue to be listed on The New York Stock
     Exchange, Inc. or quoted on the Nasdaq National Market upon the
     consummation of the applicable transaction, in each case on the date the
     applicable transaction agreement with such Public Company is entered into
     by the Company or any of its Subsidiaries

            "Public Company Business Combination Transaction" means any Business
     Combination Transaction between the Company or any of its Subsidiaries and
     a Public Company or any of its Subsidiaries.

            "Qualified Public Offering" shall mean the closing of an
     underwritten public offering of shares of Common Stock pursuant to an
     effective registration statement (other than on Form S-4, Form S-8 or their
     equivalent) filed by the Company under the Securities Act of 1933, as
     amended, in which (i) the Company receives aggregate gross proceeds (before
     deduction of underwriting discounts and expenses of sale) of at least
     $50,000,000, (ii) the per share price at which such shares are sold in the
     offering (before deduction of underwriting discounts and expenses of sale)
     is at least two times the weighted average of

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<PAGE>

     the issuance price of all shares of Preferred Stock that have theretofore
     been issued, subject to adjustment to such price pursuant to subsections
     5(e), (f), (g), (i) and (j) of this Certificate of Designations and (iii)
     the Common Stock has been accepted for listing on The New York Stock
     Exchange, Inc. or admitted for quotation to the Nasdaq National Market,
     subject to official notice of issuance.

            "Stockholders Agreement" shall mean the Stockholders Agreement dated
     July 12, 2000 among the Company, the Purchasers (as defined in the
     Investment Agreement), Cambridge Telcom, Inc. and Geneseo Communications,
     Inc.

            "Subsidiary" shall mean, with respect to any Person, any other
     corporation, limited liability company, association or other business
     entity of which at least 50% of the shares of the voting stock or other
     voting rights are owned or controlled, directly or indirectly, by such
     Person or one or more other Subsidiaries of such Person.

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<PAGE>

          IN WITNESS WHEREOF, iPCS, INC. has caused this certificate to be duly
executed by its Chief Executive Officer this 28th day of December, 2000.


                                    iPCS, INC.



                                    By:    /s/ Timothy M. Yager
                                       -------------------------------
                                    Name:  Timothy M. Yager
                                    Title: President and CEO

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