COMMON STOCK PURCHASE WARRANT

THIS WARRANT AND THE SHARES OF COMMON STOCK WHICH MAY BE PURCHASED UPON THE
EXERCISE OF THIS WARRANT HAVE BEEN ACQUIRED SOLELY FOR INVESTMENT AND HAVE NOT
BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR ANY
STATE SECURITIES LAWS. SUCH SECURITIES MAY NOT BE SOLD, OFFERED FOR SALE,
PLEDGED OR HYPOTHECATED IN THE ABSENCE OF SUCH REGISTRATION OR AN OPINION OF
COUNSEL SATISFACTORY TO THE COMPANY AND ITS COUNSEL THAT SUCH SALE, OFFER,
PLEDGE OR HYPOTHECATION IS EXEMPT FROM THE REGISTRATION AND PROSPECTUS DELIVERY
REQUIREMENTS OF THE ACT AND OF ANY APPLICABLE STATE SECURITIES LAWS UNLESS SOLD
PURSUANT TO RULE 144 OF THE ACT. THIS WARRANT MAY NOT BE TRANSFERRED BY HOLDER
WITHOUT THE PRIOR WRITTEN CONSENT OF THE COMPANY, WHICH CONSENT MAY BE WITHHELD
AT THE SOLE DISCRETION OF THE COMPANY.

                                                    VOID AFTER FEBRUARY 17, 1999

NO. CS-01                          8X8, INC.

                WARRANT TO PURCHASE 10,000 SHARES OF COMMON STOCK

                                   ----------

        THIS CERTIFIES THAT, Stanford University (the "HOLDER") is entitled to
subscribe for and purchase 10,000 shares (as adjusted pursuant to Section 3
hereof) of the fully paid and nonassessable Common Stock, par value $0.001 per
share, (the "SHARES"), of 8x8, Inc., a Delaware corporation (the "COMPANY"), at
the price of $5.50 per share (the "EXERCISE PRICE") (as adjusted pursuant to
Section 3 hereof), subject to the provisions and upon the terms and conditions
hereinafter set forth.

        1.     Method of Exercise; Payment.

               (a) Cash Exercise. The purchase rights represented by this
Warrant may be exercised by the Holder, in whole or in part, by the surrender of
this Warrant (with the notice of exercise form attached hereto as Exhibit A duly
executed) at the principal office of the Company, and by the payment to the
Company, by certified, cashier's or other check acceptable to the Company, of an
amount equal to the aggregate Exercise Price of the shares being purchased.

               (b)    Net Issue Exercise.

                      (i) In lieu of exercising this Warrant, the Holder may
elect to receive shares equal to the value of this Warrant (or the portion
thereof being cancelled) by surrender of this Warrant at the principal office of
the Company together with notice of such election, in which event

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<PAGE>   2

the Company shall issue to the Holder a number of shares of the Company's Common
Stock computed using the following formula:

               X = Y (A-B)
                   ------
                     A

Where X  =  the number of shares of Common Stock to be issued to the Holder.

      Y  =  the number of shares of Common Stock purchasable under this Warrant.

      A  =  the fair market value of one share of the Company's Common Stock.

      B  =  the Exercise Price (as adjusted to the date of such calculation).

                      (ii) This Warrant shall automatically be exercised
pursuant to Section 1(b) hereof immediately before its expiration pursuant to
Section 12 hereof unless Holder notifies the Company in writing to the contrary
before such termination.

               (c) Fair Market Value. For purposes of this Section 1, the fair
market value of the Company's Common Stock shall mean:

                      (i) The average of the closing bid and asked prices of the
Company's Common Stock quoted in the Over-The-Counter Market Summary or the
closing price quoted on any exchange on which the Common Stock is listed,
whichever is applicable, as published in the Western Edition of The Wall Street
Journal for the ten trading days prior to the date of determination of fair
market value;

                      (ii) If the Company's Common Stock is not traded
Over-The-Counter or on an exchange, fair market value of the Common Stock per
share shall be the price per share which the Company could obtain from a willing
buyer for shares sold by the Company from authorized but unissued shares of
Common Stock as such price shall be determined in good faith by the Board of
Directors of the Company.

               (d) Stock Certificates. In the event of any exercise of the
rights represented by this Warrant, certificates for the shares of Common Stock
so purchased shall be delivered to the Holder within a reasonable time and,
unless this Warrant has been fully exercised or has expired, a new Warrant
representing the shares with respect to which this Warrant shall not have been
exercised shall also be issued to the Holder within such time.

        2. Stock Fully Paid; Reservation of Shares. All of the Shares issuable
upon the exercise of the rights represented by this Warrant will, upon issuance
and receipt of the Exercise Price therefor, be fully paid and nonassessable, and
free from all taxes, liens and charges with respect to

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the issue thereof. During the period within which the rights represented by this
Warrant may be exercised, the Company shall at all times have authorized and
reserved for issuance sufficient shares of its Common Stock to provide for the
exercise of the rights represented by this Warrant.

        3. Stock Splits, Dividends and Combinations. Subject to the provisions
of Section 12 hereof, in the event that the Company shall at any time subdivide
the outstanding shares of Common Stock or shall issue a stock dividend on its
outstanding shares of Common Stock the number of Shares issuable upon exercise
of this Warrant immediately prior to such subdivision or to the issuance of such
stock dividend shall be proportionately increased, and the Exercise Price shall
be proportionately decreased, and in the event that the Company shall at any
time combine the outstanding shares of Common Stock the number of Shares
issuable upon exercise of this Warrant immediately prior to such combination
shall be proportionately decreased, and the Exercise Price shall be
proportionately increased, effective at the close of business on the date of
such subdivision, stock dividend or combination, as the case may be.

        4. Notice of Adjustments. Whenever the number of Shares purchasable
hereunder or the Exercise Price thereof shall be adjusted pursuant to Section 3
hereof, the Company shall provide notice by first class mail to the holder of
this Warrant setting forth, in reasonable detail, the event requiring the
adjustment, the amount of the adjustment, the method by which such adjustment
was calculated, and the number of Shares which may be purchased and the Exercise
Price therefor after giving effect to such adjustment.

        5.     Repurchase on Sale, Merger or Consolidation of the Company.

               (a) "Acquisition". For the purpose of this Warrant, "Acquisition"
means any reclassification or change of the Common Stock (other than a change in
par value, or as a result of a subdivision or combination), or any consolidation
or merger of the Company with or into another corporation (other than a merger
with another corporation in which the Company is a continuing corporation and
which does not result in any reclassification or change of outstanding
securities issuable upon exercise of this Warrant), or any sale of all or
substantially all of the assets of the Company.

               (b) Assumption of Warrant. If upon the closing of any Acquisition
the successor entity assumes the obligations of this Warrant, then this Warrant
shall be exercisable for the same amount and type of securities, cash, and
property as would be payable for the Shares issuable upon exercise of the
unexercised portion of this Warrant as if such Shares were outstanding on the
record date for the Acquisition and subsequent closing. If upon the closing of
any Acquisition the successor entity assumes the obligations of this Warrant,
the exercise price of the Warrant shall be adjusted such that the exercise price
for the amount of securities, cash and property as would be payable for the
Shares issuable upon exercise of the unexercised portion of this Warrant as if
such Shares were outstanding on the record date for the Acquisition and
subsequent closing, is set at an amount equal to the Warrant Price, and such
that the aggregate exercise price for this Warrant is set such that it is equal
to the Warrant Price multiplied by the number of the Shares.


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               (c) Non-assumption; Conversion. If upon the closing of any
Acquisition the successor entity does not assume the obligations of this Warrant
and Holder has not otherwise exercised this Warrant in full, then the
unexercised portion of this Warrant shall be deemed to have been automatically
converted pursuant to Section 1(b) and thereafter the Holder shall participate
in the Acquisition on the same terms as other holders of the same class of
securities of the Company.

        6. Fractional Shares. No fractional shares of Common Stock will be
issued in connection with any exercise hereunder. In lieu of such fractional
shares the Company shall make a cash payment therefor based upon the Exercise
Price then in effect.

        7. Representations of the Company. The Company represents that all
corporate actions on the part of the Company, its officers, directors and
shareholders necessary for the sale and issuance of the Shares pursuant hereto
and the performance of the Company's obligations hereunder were taken prior to
and are effective as of the effective date of this Warrant.

        8. Representations and Warranties by the Holder. The Holder represents
and warrants to the Company as follows:

               (a) This Warrant and the Shares issuable upon exercise thereof
are being acquired for its own account, for investment and not with a view to,
or for resale in connection with, any distribution or public offering thereof
within the meaning of the Securities Act of 1933, as amended (the "ACT"). Upon
exercise of this Warrant, the Holder shall, if so requested by the Company,
confirm in writing, in a form satisfactory to the Company, that the securities
issuable upon exercise of this Warrant are being acquired for investment and not
with a view toward distribution or resale.

               (b) The Holder understands that the Warrant and the Shares have
not been registered under the Act by reason of their issuance in a transaction
exempt from the registration and prospectus delivery requirements of the Act
pursuant to Section 4(2) thereof, and that they must be held by the Holder
indefinitely, and that the Holder must therefore bear the economic risk of such
investment indefinitely, unless a subsequent disposition thereof is registered
under the Act or is exempted from such registration.

               (c) The Holder has such knowledge and experience in financial and
business matters that it is capable of evaluating the merits and risks of the
purchase of this Warrant and the Shares purchasable pursuant to the terms of
this Warrant and of protecting its interests in connection therewith.

               (d) The Holder is able to bear the economic risk of the purchase
of the Shares pursuant to the terms of this Warrant.

        9.     Restrictive Legend.

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               The Shares issuable upon exercise of this Warrant (unless
registered under the Act) shall be stamped or imprinted with a legend in
substantially the following form:

               THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR
               INVESTMENT AND NOT WITH A VIEW TO, OR IN CONNECTION WITH, THE
               SALE OR DISTRIBUTION THEREOF, AND HAVE NOT BEEN REGISTERED UNDER
               THE SECURITIES ACT OF 1933, AS AMENDED. SUCH SHARES MAY NOT BE
               SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR UNLESS
               THE COMPANY RECEIVES AN OPINION OF COUNSEL REASONABLY ACCEPTABLE
               TO IT STATING THAT SUCH SALE OR TRANSFER IS EXEMPT FROM THE
               REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF THE ACT.
               COPIES OF THE AGREEMENT COVERING THE PURCHASE OF THESE SHARES AND
               RESTRICTING THEIR TRANSFER MAY BE OBTAINED AT NO COST BY WRITTEN
               REQUEST MADE BY THE HOLDER OF RECORD OF THIS CERTIFICATE TO THE
               SECRETARY OF THE CORPORATION AT THE PRINCIPAL EXECUTIVE OFFICES
               OF THE CORPORATION.

        10. Restrictions Upon Transfer and Removal of Legend.

               (a) The Holder may not transfer or assign (by operation of law or
otherwise) this Warrant without the prior written consent of the Company, which
consent may be withheld in the sole discretion of the Company.

               (b) The Company need not register a transfer of Shares bearing
the restrictive legend set forth in Section 9 hereof, unless the conditions
specified in such legend are satisfied. The Company may also instruct its
transfer agent not to register the transfer of the Shares, unless one of the
conditions specified in the legend referred to in Section 9 hereof is satisfied.

               (c) Notwithstanding the provisions of paragraph (c) above, no
opinion of counsel or "no-action" letter shall be necessary for a transfer
without consideration by any holder (i) to an affiliate of the holder, (ii) if
such holder is a partnership, to a partner or retired partner of such
partnership who retires after the date hereof or to the estate of any such
partner or retired partner, (iii) if such holder is a corporation, to a
shareholder of such corporation, or to any other corporation under common
control, direct or indirect, with such holder, or (iv) by gift, will or
intestate succession of any individual holder to his spouse or siblings, or to
the lineal descendants or ancestors of such holder or his spouse, if the
transferee agrees in writing to be subject to the terms hereof to the same
extent as if such transferee were the original holder hereunder.

        11. Rights of Shareholders. No holder of this Warrant shall be entitled,
as a Warrant holder, to vote or receive dividends or be deemed the holder of
Common Stock or any other securities of the Company which may at any time be
issuable on the exercise hereof for any purpose, nor shall anything contained
herein be construed to confer upon the holder of this Warrant, as such,


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any of the rights of a shareholder of the Company or any right to vote for the
election of directors or upon any matter submitted to shareholders at any
meeting thereof, or to give or withhold consent to any corporate action (whether
upon any recapitalization, issuance of stock, reclassification of stock, change
of par value, consolidation, merger, conveyance, or otherwise) or to receive
notice of meetings, or to receive dividends or subscription rights or otherwise
until the Warrant shall have been exercised and the Shares purchasable upon the
exercise hereof shall have become deliverable, as provided herein.

        12. Expiration of Warrant. This Warrant shall expire and shall no longer
be exercisable at 5:00 p.m., Santa Clara,California local time, on February 17,
1999. Further, the warrant shall expire and shall no longer be exercisable if
Stanford University calls upon the Company to provide assured funding of $50,000
to Stanford University in any academic year of Stanford University, as set forth
in paragraph 3 of the letter agreement dated February 13, 1998 between the
Company and Stanford University.

        13. Notices, Etc. All notices and other communications from the Company
to the Holder shall be mailed by first class registered or certified mail,
postage prepaid, at such address as may have been furnished to the Company in
writing by the Holder.

        14. Governing Law, Headings. This Warrant is being delivered in the
State of Delaware and shall be construed and enforced in accordance with and
governed by the laws of such State. The headings in this Warrant are for
purposes of reference only, and shall not limit or otherwise affect any of the
terms hereof.

        Issued on February 17, 1998.


                                         8X8, INC.


                                         By:    /s/ BRETT D. BYERS
                                            ------------------------------------
                                         Name:  Brett D. Byers
                                              ----------------------------------
                                         Title: General Counsel & Vice President
                                               ---------------------------------

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<PAGE>   7

                                    EXHIBIT A
                               NOTICE OF EXERCISE

TO:     8x8, Inc.
        2445 Mission College Blvd.
        Santa Clara, CA 95054
        Attention:  Chief Financial Officer

        1. The undersigned hereby elects to purchase __________ shares of Common
Stock of 8x8, Inc. pursuant to the terms of the attached Warrant.

        2. Method of Exercise (Please initial the applicable blank):

               ___    The undersigned elects to exercise the attached Warrant by
                      means of a cash payment, and tenders herewith payment in
                      full for the purchase price of the shares being purchased,
                      together with all applicable transfer taxes, if any.

               ___    The undersigned elects to exercise the attached Warrant by
                      means of the net exercise provisions of Section 1(b) of
                      the Warrant.

        3. Please issue a certificate or certificates representing said shares
of Common Stock in the name of the undersigned or in such other name as is
specified below:
                        ---------------------------------
                                     (Name)

                        ---------------------------------

                        ---------------------------------
                                    (Address)

        4. The undersigned hereby represents and warrants that the aforesaid
shares of Common Stock are being acquired for the account of the undersigned for
investment and not with a view to, or for resale, in connection with the
distribution thereof, and that the undersigned has no present intention of
distributing or reselling such shares and all representations and warranties of
the undersigned set forth in Section 8 of the attached Warrant are true and
correct as of the date hereof. In support thereof, the undersigned hereby
delivers an Investment Representation Statement in a form substantially similar
to the form attached to the Warrant as Exhibit B.


                                         ---------------------------------------
                                                     (Signature)

                                         Name:
                                              ----------------------------------
                                         Title:
                                               ---------------------------------

                                         ---------------------------------------
                                                          (Date)


<PAGE>   8

                                    EXHIBIT B
                       INVESTMENT REPRESENTATION STATEMENT

PURCHASER  :     _________________________
SELLER     :     8x8, Inc.
COMPANY    :     8x8, Inc.
SECURITY   :     COMMON STOCK ISSUED UPON EXERCISE OF THE STOCK PURCHASE WARRANT
                 ISSUED ON February 17, 1998
AMOUNT     :     __________ SHARES
DATE       :     ____________, 19__

In connection with the purchase of the above-listed Securities, the Purchaser
represents to the Seller and to the Company the following:

        (a) Purchaser is aware of the Company's business affairs and financial
condition, and has acquired sufficient information about the Company to reach an
informed and knowledgeable decision to acquire the Securities. Purchaser is
purchasing these Securities for its own account for investment purposes only and
not with a view to, or for the resale in connection with, any "distribution"
thereof for purposes of the Securities Act of 1933, as amended (the "Securities
Act").

        (b) Purchaser understands that the Securities have not been registered
under the Securities Act in reliance upon a specific exemption therefrom, which
exemption depends upon, among other things, the bona fide nature of its
investment intent as expressed herein. In this connection, Purchaser understands
that, in the view of the Securities and Exchange Commission (the "SEC"), the
statutory basis for such exemption may be unavailable if its representation was
predicated solely upon a present intention to hold these Securities for the
minimum capital gains period specified under tax statutes, for a deferred sale,
for or until an increase or decrease in the market price of the Securities, or
for a period of one year or any other fixed period in the future.

        (c) Purchaser further understands that the Securities must be held
indefinitely unless subsequently registered under the Securities Act or unless
an exemption from registration is otherwise available. Moreover, Purchaser
understands that the Company is under no obligation to register the Securities.
In addition, Purchaser understands that the certificate evidencing the
Securities will be imprinted with a legend which prohibits the transfer of the
Securities unless they are registered or such registration is not required in
the opinion of counsel for the Company.

        (d) Purchaser is familiar with the provisions of Rule 144, promulgated
under the Securities Act, which, in substance, permits limited public resale of
"restricted securities" acquired, directly or indirectly, from the issuer
thereof, in a non-public offering subject to the satisfaction of certain
conditions. The Securities may be resold in certain limited circumstances
subject to the provisions of Rule 144, which requires among other things: (1)
the availability of certain public information about the Company, (2) the resale
occurring not less than one years after the party has purchased, and made full
payment for, within the meaning of Rule 144, the securities to be sold; and, in
the case of an affiliate, or of a non-affiliate who has held the securities less
than two years, (3) the sale being made through a broker in an unsolicited
"broker's transaction" or in transactions directly with a market maker (as said
term is defined under the Securities Exchange Act of 1934) and the amount of
securities being sold during any three month period not exceeding the specified
limitations stated therein, if applicable.


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<PAGE>   9

        (e) Purchaser further understands that in the event all of the
applicable requirements of Rule 144 are not satisfied, registration under the
Securities Act, compliance with Regulation A, or some other registration
exemption will be required; and that, notwithstanding the fact that Rule 144 is
not exclusive, the Staff of the SEC has expressed its opinion that persons
proposing to sell private placement securities other than in a registered
offering and otherwise than pursuant to Rule 144 will have a substantial burden
of proof in establishing that an exemption from registration is available for
such offers or sales, and that such persons and their respective brokers who
participate in such transactions do so at their own risk.

        (f) Purchaser agrees, in connection with any underwritten public
offering of the Company's securities, (1) not to sell, make short sale of, loan,
grant any options for the purchase of, or otherwise dispose of any shares of
common stock of the Company held by Purchaser (other than those shares included
in the registration) without the prior written consent of the Company or the
underwriters managing such underwritten public offering of the Company's
securities for one hundred eighty (180) days from the effective date of such
registration, and (2) Purchaser further agrees to execute any agreement
reflecting (1) above as may be requested by the underwriters at the time of the
public offering; provided however that the officers and directors of the Company
who own the stock of the Company also agree to such restrictions.



                                       Purchaser:
                                                 -------------------------------


                                       By:
                                          --------------------------------------
                                       Name: 
                                             -----------------------------------
                                       Title:    
                                             -----------------------------------
                                       Date:                              , 199_
                                             -----------------------------

                                       9

<PAGE>   10

                                    EXHIBIT C
                                FORM OF TRANSFER
                  (To be signed only upon transfer of Warrant)


        FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers
unto _______________________________________________ the right represented by
the attached Warrant to purchase ____________* shares of Common Stock of 8x8,
Inc., to which the attached Warrant relates, and appoints ______________
Attorney to transfer such right on the books of 8x8, Inc., with full power of
substitution in the premises.

        Dated:
               --------------------

                                      ------------------------------------------
                                      (Signature must conform in all respects to
                                      name of Holder as specified on the face of
                                      the Warrant)
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------



                                      ------------------------------------------
                                                     (Address)


Signed in the presence of:

----------------------------

* Insert here the number of shares without making any adjustment for additional
shares of Common Stock or any other stock or other securities or property or
cash which, pursuant to the adjustment provisions of the Warrant, may be
deliverable upon exercise.

** NOTE THAT VALID TRANSFER OF THE WARRANT IS SUBJECT TO PRIOR WRITTEN CONSENT
OF 8X8, INC., WHICH CONSENT MAY BE WITHHELD AT THE SOLE DISCRETION OF 8X8, INC.
PURSUANT TO SECTION 10(a) OF THE WARRANT.

Source: OneCLE Business Contracts.