<PAGE>
 
                                                                    EXHIBIT 10.3
 
                      OBJECTIVE SYSTEMS INTEGRATORS, INC.

                       1995 EMPLOYEE STOCK PURCHASE PLAN
                      (AS AMENDED THROUGH JULY 18, 1997)

     The following constitute the provisions of the 1995 Employee Stock Purchase
Plan of Objective Systems Integrators, Inc.

     1.   Purpose.  The purpose of the Plan is to provide employees of the
          -------                                                         
Company and its Designated Subsidiaries with an opportunity to purchase Common
Stock of the Company through accumulated payroll deductions.  It is the
intention of the Company to have the Plan qualify as an "Employee Stock Purchase
Plan" under Section 423 of the Internal Revenue Code of 1986, as amended.  The
provisions of the Plan, accordingly, shall be construed so as to extend and
limit participation in a manner consistent with the requirements of that section
of the Code.

     2.   Definitions.
          ----------- 

          (a)  "Board" shall mean the Board of Directors of the Company.
                -----                                                   

          (b)  "Code" shall mean the Internal Revenue Code of 1986, as amended.
                ----                                                           

          (c)  "Common Stock" shall mean the Common Stock of the Company.
                ------------                                             

          (d)  "Company" shall mean Objective Systems Integrators, Inc. and any
                -------                                                        
Designated Subsidiary of the Company.

          (e)  "Compensation" shall mean all W-2 compensation of the
                ------------
participant.

          (f)  "Designated Subsidiaries" shall mean the Subsidiaries which have
                -----------------------
been designated by the Board from time to time in its sole discretion as
eligible to participate in the Plan.

          (g)  "Employee" shall mean any individual who is an Employee of the
                --------
Company for tax purposes whose customary employment with the Company is at least
twenty (20) hours per week and more than five (5) months in any calendar year.
For purposes of the Plan, the employment relationship shall be treated as
continuing intact while the individual is on sick leave or other leave of
absence approved by the Company. Where the period of leave exceeds 90 days and
the individual's right to reemployment is not guaranteed either by statute or by
contract, the employment relationship will be deemed to have terminated on the
91st day of such leave.

          (h)  "Enrollment Date" shall mean the first day of each Offering
                ---------------
Period.

          (i)  "Exercise Date" shall mean the last day of each Purchase Period.
                -------------                                                  
<PAGE>
 
          (j)  "Fair Market Value" shall mean, as of any date, the value of
                -----------------
Common Stock determined as follows:

               (1)  If the Common Stock is listed on any established stock
exchange or a national market system, including without limitation the Nasdaq
National Market of the National Association of Securities Dealers, Inc.
Automated Quotation ("NASDAQ") System, its Fair Market Value shall be the
closing sale price for the Common Stock (or the mean of the closing bid and
asked prices, if no sales were reported), as quoted on such exchange (or the
exchange with the greatest volume of trading in Common Stock) or system on the
date of such determination, as reported in The Wall Street Journal or such other
source as the Board deems reliable, or;

               (2)  If the Common Stock is quoted on the NASDAQ System (but not
on the Nasdaq National Market thereof) or is regularly quoted by a recognized
securities dealer but selling prices are not reported, its Fair Market Value
shall be the mean of the closing bid and asked prices for the Common Stock on
the date of such determination, as reported in The Wall Street Journal or such
other source as the Board deems reliable, or;

               (3)  In the absence of an established market for the Common
Stock, the Fair Market Value thereof shall be determined in good faith by the
Board.

               (4)  For purposes of the Enrollment Date under the first Offering
Period, the Fair Market Value shall be the initial price to the public as set
forth in the final Prospectus included within the Registration Statement in Form
S-1 filed with the Securities and Exchange Commission for the initial public
offering of the Company's Common Stock.

          (k)  "Offering Period" shall mean the period of approximately twenty-
                ---------------
four (24) months during which an option granted pursuant to the Plan may be
exercised, commencing on the first Trading Day on or after April 30 and October
31 of each year and terminating on the last Trading Day in the periods ending
twenty-four months later. The first Offering Period shall begin on the effective
date of the Company's initial public offering of its Common Stock that is
registered with the Securities and Exchange Commission and shall end on the last
Trading Day on or before October 31, 1997. The duration and timing of Offering
Periods may be changed pursuant to Section 4 of this Plan.

          (l)  "Plan" shall mean this Employee Stock Purchase Plan.
                ----                                               

          (m)  "Purchase Price" shall mean an amount equal to 85% of the Fair
                --------------
Market Value of a share of Common Stock on the Enrollment Date or on the
Exercise Date, whichever is lower.

          (n)  "Purchase Period" shall mean the approximately six month period
                ---------------                                               
commencing after one Exercise Date and ending with the next Exercise Date,
except that the first Purchase Period of any Offering Period shall commence on
the Enrollment Date and end with the next Exercise Date.
<PAGE>
 
          (o)  "Reserves" shall mean the number of shares of Common Stock
                --------
covered by each option under the Plan which have not yet been exercised and the
number of shares of Common Stock which have been authorized for issuance under
the Plan but not yet placed under option.

          (p)  "Subsidiary" shall mean a corporation, domestic or foreign, of
                ----------
which not less than 50% of the voting shares are held by the Company or a
Subsidiary, whether or not such corporation now exists or is hereafter organized
or acquired by the Company or a Subsidiary.

          (q)  "Trading Day" shall mean a day on which national stock exchanges
                -----------
and the Nasdaq System are open for trading.

     3.   Eligibility.
          ----------- 

          (a)  Any Employee (as defined in Section 2(g)), who shall be employed
by the Company on a given Enrollment Date shall be eligible to participate in
the Plan.

          (b)  Any provisions of the Plan to the contrary notwithstanding, no
Employee shall be granted an option under the Plan (i) if, immediately after the
grant, such Employee (or any other person whose stock would be attributed to
such Employee pursuant to Section 424(d) of the Code) would own capital stock of
the Company and/or hold outstanding options to purchase such stock possessing
five percent (5%) or more of the total combined voting power or value of all
classes of the capital stock of the Company or of any Subsidiary, or (ii) which
permits his or her rights to purchase stock under all employee stock purchase
plans of the Company and its subsidiaries to accrue at a rate which exceeds
twenty-five thousand dollars ($25,000) worth of stock (determined at the fair
market value of the shares at the time such option is granted) for each calendar
year in which such option is outstanding at any time.

     4.   Offering Periods.  The Plan shall be implemented by consecutive,
          ----------------                                                
overlapping Offering Periods with a new Offering Period commencing on the first
Trading Day on or after April 30 and October 31 each year, or on such other date
as the Board shall determine, and continuing thereafter until terminated in
accordance with Section 19 hereof.  The first Offering Period shall begin on the
Effective Date of the Company's initial public offering of its Common Stock that
is registered with the Securities and Exchange Commission.  The Board shall have
the power to change the duration of Offering Periods (including the commencement
dates thereof) with respect to future offerings without shareholder approval if
such change is announced at least five (5) days prior to the scheduled beginning
of the first Offering Period to be affected thereafter.

     5.   Participation.
          ------------- 

          (a)  An eligible Employee may become a participant in the Plan by
completing a subscription agreement authorizing payroll deductions in the form
of Exhibit A to this Plan and filing 
<PAGE>
 
it with the Company's payroll office prior to the applicable Enrollment Date.

          (b)  Payroll deductions for a participant shall commence on the first
payroll following the Enrollment Date and shall end on the last payroll in the
Offering Period to which such authorization is applicable, unless sooner
terminated by the participant as provided in Section 10 hereof.

     6.   Payroll Deductions.
          ------------------ 

          (a)  At the time a participant files his or her subscription
agreement, he or she shall elect to have payroll deductions made on each pay day
during the Offering Period in an amount not exceeding fifteen percent (15%) of
the Compensation which he or she receives on each pay day during the Offering
Period, and the aggregate of such payroll deductions during the Offering Period
shall not exceed fifteen percent (15%) of the participant's Compensation during
said Offering Period.

          (b)  All payroll deductions made for a participant shall be credited
to his or her account under the Plan and will be withheld in whole percentages
only. A participant may not make any additional payments into such account.

          (c)  A participant may discontinue his or her participation in the
Plan as provided in Section 10 hereof, or may increase or decrease the rate of
his or her payroll deductions once during any Purchase Period by completing or
filing with the Company a new subscription agreement authorizing a change in
payroll deduction rate. The Board may, in its discretion, limit the number of
participation rate changes during any Purchase Period. The change in rate shall
be effective with the first full payroll period following five (5) business days
after the Company's receipt of the new subscription agreement unless the Company
elects to process a given change in participation more quickly. A participant's
subscription agreement shall remain in effect for successive Offering Periods
unless terminated as provided in Section 10 hereof.

          (d)  Notwithstanding the foregoing, to the extent necessary to comply
with Section 423(b)(8) of the Code and Section 3(b) hereof, a participant's
payroll deductions may be decreased to 0% at such time during any Purchase
Period which is scheduled to end during the current calendar year (the "Current
Purchase Period") that the aggregate of all payroll deductions which were
previously used to purchase stock under the Plan in a prior Purchase Period
which ended during that calendar year plus all payroll deductions accumulated
with respect to the Current Purchase Period equal $21,250. Payroll deductions
shall recommence at the rate provided in such participant's subscription
agreement at the beginning of the first Purchase Period which is scheduled to
end in the following calendar year, unless terminated by the participant as
provided in Section 10 hereof.

          (e)  At the time the option is exercised, in whole or in part, or at
the time some or all of the Company's Common Stock issued under the Plan is
disposed of, the participant must make 
<PAGE>
 
adequate provision for the Company's federal, state, or other tax withholding
obligations, if any, which arise upon the exercise of the option or the
disposition of the Common Stock. At any time, the Company may, but will not be
obligated to, withhold from the participant's compensation the amount necessary
for the Company to meet applicable withholding obligations, including any
withholding required to make available to the Company any tax deductions or
benefits attributable to sale or early disposition of Common Stock by the
Employee.

     7.   Grant of Option.  On the Enrollment Date of each Offering Period, each
          ---------------                                                       
eligible Employee participating in such Offering Period shall be granted an
option to purchase on each Exercise Date during such Offering Period (at the
applicable Purchase Price) up to a number of shares of the Company's Common
Stock determined by dividing such Employee's payroll deductions accumulated
prior to such Exercise Date and retained in the Participant's account as of the
Exercise Date by the applicable Purchase Price; provided that in no event shall
an Employee be permitted to purchase during each Purchase Period more than a
number of Shares determined by dividing $12,500 by the Fair Market Value of a
share of the Company's Common Stock on the Enrollment Date, and provided further
that such purchase shall be subject to the limitations set forth in Sections
3(b) and 12 hereof. Exercise of the option shall occur as provided in Section 8
hereof, unless the participant has withdrawn pursuant to Section 10 hereof, and
shall expire on the last day of the Offering Period.

     8.   Exercise of Option.  Unless a participant withdraws from the Plan as
          ------------------                                                  
provided in Section 10 hereof, his or her option for the purchase of shares will
be exercised automatically on the Exercise Date, and the maximum number of full
shares subject to option shall be purchased for such participant at the
applicable Purchase Price with the accumulated payroll deductions in his or her
account.  No fractional shares will be purchased; any payroll deductions
accumulated in a participant's account which are not sufficient to purchase a
full share shall be retained in the participant's account for the subsequent
Purchase Period or Offering Period, subject to earlier withdrawal by the
participant as provided in Section 10 hereof.  Any other monies left over in a
participant's account after the Exercise Date shall be returned to the
participant.  During a participant's lifetime, a participant's option to
purchase shares hereunder is exercisable only by him or her.

     9.   Delivery.  As promptly as practicable after each Exercise Date on 
          --------
which a purchase of shares occurs, the Company shall arrange the delivery to
each participant, as appropriate, of a certificate representing the shares
purchased upon exercise of his or her option.

     10.  Withdrawal; Termination of Employment.
          ------------------------------------- 

          (a)  A participant may withdraw all but not less than all the payroll
deductions credited to his or her account and not yet used to exercise his or
her option under the Plan at any time by giving written notice to the Company in
the form of Exhibit B to this Plan.  All of the 

                                      -5-
<PAGE>
 
participant's payroll deductions credited to his or her account will be paid to
such participant promptly after receipt of notice of withdrawal and such
participant's option for the Offering Period will be automatically terminated,
and no further payroll deductions for the purchase of shares will be made for
such Offering Period. If a participant withdraws from an Offering Period,
payroll deductions will not resume at the beginning of the succeeding Offering
Period unless the participant delivers to the Company a new subscription
agreement.

          (b)  Upon a participant's ceasing to be an Employee (as defined in
Section 2(g) hereof), for any reason, he or she will be deemed to have elected
to withdraw from the Plan and the payroll deductions credited to such
participant's account during the Offering Period but not yet used to exercise
the option will be returned to such participant or, in the case of his or her
death, to the person or persons entitled thereto under Section 14 hereof, and
such participant's option will be automatically terminated. The preceding
sentence notwithstanding, a participant who receives payment in lieu of notice
of termination of employment shall be treated as continuing to be an Employee
for the participant's customary number of hours per week of employment during
the period in which the participant is subject to such payment in lieu of
notice.

     11.  Interest.  No interest shall accrue on the payroll deductions of a
          --------                                                          
participant in the Plan.

     12.  Stock.
          ----- 

          (a)  The maximum number of shares of the Company's Common Stock which
shall be made available for sale under the Plan shall be 1,487,500, subject to
adjustment upon changes in capitalization of the Company as provided in Section
18 hereof. If, on a given Exercise Date, the number of shares with respect to
which options are to be exercised exceeds the number of shares then available
under the Plan, the Company shall make a pro rata allocation of the shares
remaining available for purchase in as uniform a manner as shall be practicable
and as it shall deter mine to be equitable.

          (b)  The participant will have no interest or voting right in shares
covered by his option until such option has been exercised.

          (c)  Shares to be delivered to a participant under the Plan will be
registered in the name of the participant or in the name of the participant and
his or her spouse.

     13.  Administration.
          -------------- 

          (a)  Administrative Body.  The Plan shall be administered by the 
               -------------------
Board or a committee of members of the Board appointed by the Board. The Board
or its committee shall have 
<PAGE>
 
full and exclusive discretionary authority to construe, interpret and apply the
terms of the Plan, to determine eligibility and to adjudicate all disputed
claims filed under the Plan. Every finding, decision and determination made by
the Board or its committee shall, to the full extent permitted by law, be final
and binding upon all parties.

          (b)  Rule 16b-3 Limitations.  Notwithstanding the provisions of 
               ----------------------
Subsection (a) of this Section 13, in the event that Rule 16b-3 promulgated
under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or
any successor provision ("Rule 16b-3") provides specific requirements for the
administrators of plans of this type, the Plan shall be only administered by
such a body and in such a manner as shall comply with the applicable
requirements of Rule 16b-3. Unless permitted by Rule 16b-3, no discretion
concerning decisions regarding the Plan shall be afforded to any committee or
person that is not "disinterested" as that term is used in Rule 16b-3.

     14.  Designation of Beneficiary.
          -------------------------- 

          (a)  A participant may file a written designation of a beneficiary who
is to receive any shares and cash, if any, from the participant's account under
the Plan in the event of such participant's death subsequent to an Exercise
Date on which the option is exercised but prior to delivery to such participant
of such shares and cash. In addition, a participant may file a written
designation of a beneficiary who is to receive any cash from the participant's
account under the Plan in the event of such participant's death prior to
exercise of the option. If a participant is married and the designated
beneficiary is not the spouse, spousal consent shall be required for such
designation to be effective.

          (b)  Such designation of beneficiary may be changed by the participant
at any time by written notice. In the event of the death of a participant and in
the absence of a beneficiary validly designated under the Plan who is living at
the time of such participant's death, the Company shall deliver such shares
and/or cash to the executor or administrator of the estate of the participant,
or if no such executor or administrator has been appointed (to the knowledge of
the Company), the Company, in its discretion, may deliver such shares and/or
cash to the spouse or to any one or more dependents or relatives of the
participant, or if no spouse, dependent or relative is known to the Company,
then to such other person as the Company may designate.

     15.  Transferability.  Neither payroll deductions credited to a
          ---------------                                           
participant's account nor any rights with regard to the exercise of an option or
to receive shares under the Plan may be assigned, transferred, pledged or
otherwise disposed of in any way (other than by will, the laws of descent and
distribution or as provided in Section 14 hereof) by the participant.  Any such
attempt at assignment, transfer, pledge or other disposition shall be without
effect, except that the Company may treat such act as an election to withdraw
funds from an Offering Period in accordance with Section 10 hereof.

                                      -7-
<PAGE>
 
     16.  Use of Funds.  All payroll deductions received or held by the Company
          ------------                                                         
under the Plan may be used by the Company for any corporate purpose, and the
Company shall not be obligated to segregate such payroll deductions.

     17.  Reports.  Individual accounts will be maintained for each participant
          -------                                                              
in the Plan.  Statements of account will be given to participating Employees at
least annually, which statements will set forth the amounts of payroll
deductions, the Purchase Price, the number of shares purchased and the remaining
cash balance, if any.

     18.  Adjustments Upon Changes in Capitalization, Dissolution, Liquidation,
          ---------------------------------------------------------------------
Merger or Asset Sale.
-------------------- 

          (a)  Changes in Capitalization.  Subject to any required action by the
               -------------------------                                        
shareholders of the Company, the Reserves as well as the price per share of
Common Stock covered by each option under the Plan which has not yet been
exercised shall be proportionately adjusted for any increase or decrease in the
number of issued shares of Common Stock resulting from a stock split, reverse
stock split, stock dividend, combination or reclassification of the Common
Stock, or any other increase or decrease in the number of shares of Common Stock
effected without receipt of consideration by the Company; provided, however,
that conversion of any convertible securities of the Company shall not be deemed
to have been "effected without receipt of consideration".  Such adjustment shall
be made by the Board, whose determination in that respect shall be final,
binding and conclusive.  Except as expressly provided herein, no issuance by the
Company of shares of stock of any class, or securities convertible into shares
of stock of any class, shall affect, and no adjustment by reason thereof shall
be made with respect to, the number or price of shares of Common Stock subject
to an option.

          (b)  Dissolution or Liquidation.  In the event of the proposed 
               --------------------------
dissolution or liquidation of the Company, the Offering Periods will terminate
immediately prior to the consummation of such proposed action, unless otherwise
provided by the Board.

          (c)  Merger or Asset Sale.  In the event of a proposed sale of all or
               --------------------                                            
substantially all of the assets of the Company, or the merger of the Company
with or into another corporation, each option under the Plan shall be assumed or
an equivalent option shall be substituted by such successor corporation or a
parent or subsidiary of such successor corporation, unless the Board determines,
in the exercise of its sole discretion and in lieu of such assumption or
substitution, to shorten the Offering Periods then in progress by setting a new
Exercise Date (the "New Exercise Date").  If the Board shortens the Offering
Periods then in progress in lieu of assumption or substitution in the event of a
merger or sale of assets, the Board shall notify each participant in writing, at
least ten (10) business days prior to the New Exercise Date, that the Exercise
Date for his option has been changed to the New Exercise Date and that his
option will be exercised automatically on the 

                                      -8-
<PAGE>
 
New Exercise Date, unless prior to such date he has withdrawn from the Offering
Period as provided in Section 10 hereof. For purposes of this paragraph, an
option granted under the Plan shall be deemed to be assumed if, following the
sale of assets or merger, the option confers the right to purchase, for each
share of option stock subject to the option immediately prior to the sale of
assets or merger, the consideration (whether stock, cash or other securities or
property) received in the sale of assets or merger by holders of Common Stock
for each share of Common Stock held on the effective date of the transaction
(and if such holders were offered a choice of consideration, the type of
consideration chosen by the holders of a majority of the outstanding shares of
Common Stock); provided, however, that if such consideration received in the
sale of assets or merger was not solely common stock of the successor
corporation or its parent (as defined in Section 424(e) of the Code), the Board
may, with the consent of the successor corporation, provide for the
consideration to be received upon exercise of the option to be solely common
stock of the successor corporation or its parent equal in fair market value to
the per share consideration received by holders of Common Stock and the sale of
assets or merger.

     19.  Amendment or Termination.
          ------------------------ 

          (a)  The Board of Directors of the Company may at any time and for any
reason terminate or amend the Plan.  Except as provided in Section 18 hereof, no
such termination can affect options previously granted, provided that an
Offering Period may be terminated by the Board of Directors on any Exercise Date
if the Board determines that the termination of the Plan is in the best
interests of the Company and its shareholders.  Except as provided in Section 18
hereof, no amendment may make any change in any option theretofore granted which
adversely affects the rights of any participant.  To the extent necessary to
comply with Rule 16b-3 or under Section 423 of the Code (or any successor rule
or provision or any other applicable law or regulation), the Company shall
obtain shareholder approval in such a manner and to such a degree as required.

          (b)  Without shareholder consent and without regard to whether any
participant rights may be considered to have been "adversely affected," the
Board (or its committee) shall be entitled to change the Offering Periods, limit
the frequency and/or number of changes in the amount withheld during an Offering
Period, establish the exchange ratio applicable to amounts withheld in a
currency other than U.S. dollars, permit payroll withholding in excess of the
amount designated by a participant in order to adjust for delays or mistakes in
the Company's processing of properly completed withholding elections, establish
reasonable waiting and adjustment periods and/or accounting and crediting
procedures to ensure that amounts applied toward the purchase of Common Stock
for each participant properly correspond with amounts withheld from the
participant's Compensation, and establish such other limitations or procedures
as the Board (or its committee) determines in its sole discretion advisable
which are consistent with the Plan.

     20.  Notices.  All notices or other communications by a participant to the
          -------                                                              
Company under 

                                      -9-
<PAGE>
 
or in connection with the Plan shall be deemed to have been duly given when
received in the form specified by the Company at the location, or by the person,
designated by the Company for the receipt thereof.

     21.  Conditions Upon Issuance of Shares.  Shares shall not be issued with
          ----------------------------------                                  
respect to an option unless the exercise of such option and the issuance and
delivery of such shares pursuant thereto shall comply with all applicable
provisions of law, domestic or foreign, including, without limitation, the
Securities Act of 1933, as amended, the Securities Exchange Act of 1934, as
amended, the rules and regulations promulgated thereunder, and the requirements
of any stock exchange upon which the shares may then be listed, and shall be
further subject to the approval of counsel for the Company with respect to such
compliance.

          As a condition to the exercise of an option, the Company may require
the person exercising such option to represent and warrant at the time of any
such exercise that the shares are being purchased only for investment and
without any present intention to sell or distribute such shares if, in the
opinion of counsel for the Company, such a representation is required by any of
the aforementioned applicable provisions of law.

     22.  Term of Plan.  The Plan shall become effective upon the earlier to
          ------------                                                      
occur of its adoption by the Board of Directors or its approval by the
shareholders of the Company.  It shall continue in effect for a term of ten (10)
years unless sooner terminated under Section 19 hereof.

     23.  Automatic Transfer to Low Price Offering Period.  To the extent
          -----------------------------------------------                
permitted by Rule 16b-3 of the Exchange Act, if the Fair Market Value of the
Common Stock on any Exercise Date in an Offering Period is lower than the Fair
Market Value of the Common Stock on the Enrollment Date of such Offering Period,
then all participants in such Offering Period shall be automatically withdrawn
from such Offering Period immediately after the exercise of their option on such
Exercise Date and automatically re-enrolled in the immediately following
Offering Period as of the first day thereof.

                                     -10-
<PAGE>
 
                                   EXHIBIT A
                                   ---------


                      OBJECTIVE SYSTEMS INTEGRATORS, INC.

                       1995 EMPLOYEE STOCK PURCHASE PLAN

                            SUBSCRIPTION AGREEMENT



_____ Original Application                          Enrollment Date: ___________
_____ Change in Payroll Deduction Rate
_____ Change of Beneficiary(ies)


1.   ________________________________________ hereby elects to participate in
     the Objective Systems Integrators, Inc. 1995 Employee Stock Purchase Plan
     (the "Employee Stock Purchase Plan") and subscribes to purchase shares of
     the Company's Common Stock in accordance with this Subscription Agreement
     and the Employee Stock Purchase Plan.

2.   I hereby authorize payroll deductions from each paycheck in the amount of
     _____ of my Compensation on each payday (1-15%) during the Offering Period
     in accordance with the Employee Stock Purchase Plan.  (Please note that no
     fractional percentages are permitted.)

3.   I understand that said payroll deductions shall be accumulated for the
     purchase of shares of Common Stock at the applicable Purchase Price
     determined in accordance with the Employee Stock Purchase Plan.  I
     understand that if I do not withdraw from an Offering Period, any
     accumulated payroll deductions will be used to automatically exercise my
     option.

4.   I have received a copy of the complete "Objective Systems Integrators, Inc.
     1995 Employee Stock Purchase Plan."  I understand that my participation in
     the Employee Stock Purchase Plan is in all respects subject to the terms of
     the Plan.  I understand that my ability to exercise the option under this
     Subscription Agreement is subject to obtaining shareholder approval of the
     Employee Stock Purchase Plan.

5.   Shares purchased for me under the Employee Stock Purchase Plan should be
     issued in the name(s) of (Employee or Employee and spouse only):

6.   I understand that if I dispose of any shares received by me pursuant to the
     Plan within 2 years after the Enrollment Date (the first day of the
     Offering Period during which I purchased 
<PAGE>
 
     such shares) or one year after the Exercise Date, I will be treated for
     federal income tax purposes as having received ordinary income at the time
     of such disposition in an amount equal to the excess of the fair market
     value of the shares at the time such shares were purchased over the price
     which I paid for the shares. I HEREBY AGREE TO NOTIFY THE COMPANY IN
                                  ---------------------------------------
     WRITING WITHIN 30 DAYS AFTER THE DATE OF ANY DISPOSITION OF MY SHARES AND I
     ---------------------------------------------------------------------------
     WILL MAKE ADEQUATE PROVISION FOR FEDERAL, STATE OR OTHER TAX WITHHOLDING
     ------------------------------------------------------------------------
     OBLIGATIONS, IF ANY, WHICH ARISE UPON THE DISPOSITION OF THE COMMON STOCK.
     -------------------------------------------------------------------------
     The Company may, but will not be obligated to, withhold from my
     compensation the amount necessary to meet any applicable withholding
     obligation including any withholding necessary to make available to the
     Company any tax deductions or benefits attributable to sale or early
     disposition of Common Stock by me. If I dispose of such shares at any time
     after the expiration of the 2-year and 1-year holding periods, I understand
     that I will be treated for federal income tax purposes as having received
     income only at the time of such disposition, and that such income will be
     taxed as ordinary income only to the extent of an amount equal to the
     lesser of (1) the excess of the fair market value of the shares at the time
     of such disposition over the purchase price which I paid for the shares, or
     (2) 15% of the fair market value of the shares on the first day of the
     Offering Period. The remainder of the gain, if any, recognized on such
     disposition will be taxed as capital gain.

7.   I hereby agree to be bound by the terms of the Employee Stock Purchase
     Plan.  The effectiveness of this Subscription Agreement is dependent upon
     my eligibility to participate in the Employee Stock Purchase Plan.

8.   In the event of my death, I hereby designate the following as my
     beneficiary(ies) to receive all payments and shares due me under the
     Employee Stock Purchase Plan:


NAME:  (Please print)______________________________________________
                      (First)         (Middle)               (Last)


__________________________________    __________________________________________
Relationship

                                      __________________________________________
                                      (Address)

                                      -2-
<PAGE>
 
Employee's Social
Security Number:              ____________________________________



Employee's Address:           ____________________________________

                              ____________________________________

                              ____________________________________


I UNDERSTAND THAT THIS SUBSCRIPTION AGREEMENT SHALL REMAIN IN EFFECT THROUGHOUT
SUCCESSIVE OFFERING PERIODS UNLESS TERMINATED BY ME.



Dated:_________________________     ________________________________________
                                    Signature of Employee


                                    ________________________________________
                                    Spouse's Signature (If beneficiary other
                                    than spouse)

                                      -3-
<PAGE>
 
                                   EXHIBIT B
                                   ---------


OBJECTIVE SYSTEMS INTEGRATORS, INC.

                       1995 EMPLOYEE STOCK PURCHASE PLAN

                             NOTICE OF WITHDRAWAL



     The undersigned participant in the Offering Period of the Objective Systems
Integrators, Inc. 1995 Employee Stock Purchase Plan which began on ____________,
19____ (the "Enrollment Date") hereby notifies the Company that he or she hereby
withdraws from the Offering Period.  He or she hereby directs the Company to pay
to the undersigned as promptly as practicable all the payroll deductions
credited to his or her account with respect to such Offering Period. The
undersigned understands and agrees that his or her option for such Offering
Period will be automatically terminated.  The undersigned understands further
that no further payroll deductions will be made for the purchase of shares in
the current Offering Period and the undersigned shall be eligible to participate
in succeeding Offering Periods only by delivering to the Company a new
Subscription Agreement.

                                    Name and Address of Participant:

                                    ________________________________


                                    ________________________________


                                    ________________________________



                                    Signature:


                                    ________________________________


                                    Date:__________________________

                                      -4-
<PAGE>
 
                                             OBJECTIVE SYSTEMS INTEGRATORS, INC.
ID:


                                    OPTION NUMBER:
PLAN:                               ISO
                                    ID:


Effective, you have been granted an Incentive Stock Option to buy_________
                                    ----------------------                
shares of Objective Systems Integrators, Inc. ("OSI") stock at ___________ per
share.

The total option price of the shares granted is ______________.

Shares in each period will become fully vested on the date shown.


                   Shares   Vest Type   Full Vest   Expiration
                   ------   ---------   ---------   ----------
 


By your signature and OSI's signature below, you and OSI agree that these
options are granted under. and governed by the terms and conditions of. OSI's
Stock Option Plan. as amended, and the Option Agreement, all of which are
attached and made a part of this document.


-----------------------------------     --------------------------------- 
OBJECTIVE SYSTEMS INTEGRATORS, INC.     Date



 
-----------------------------------     --------------------------------- 
Date