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                                                                  EXHIBIT 10.13

                   FORM OF WARRANT TO PURCHASE PREFERRED STOCK



        THIS WARRANT AND THE SECURITIES ISSUABLE UPON THE EXERCISE HEREOF HAVE
        NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933. THEY MAY NOT BE
        SOLD, OFFERED FOR SALE, PLEDGED, HYPOTHECATED, OR OTHERWISE TRANSFERRED
        EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE
        SECURITIES ACT OF 1933, OR AN OPINION OF COUNSEL SATISFACTORY TO THE
        COMPANY THAT REGISTRATION IS NOT REQUIRED UNDER SUCH ACT OR UNLESS SOLD
        PURSUANT TO RULE 144 UNDER SUCH ACT.

                                                                      Void after
                                                               December 31, 2003

                            OBJECTSWITCH CORPORATION
                  WARRANT TO PURCHASE SHARES OF PREFERRED STOCK

        This Warrant is issued to _____________ by ObjectSwitch Corporation, a
California corporation (the "Company"), pursuant to the terms of that certain
Note and Warrant Purchase Agreement (the "Purchase Agreement"), dated as of
December 23, 1998, in connection with the Company's issuance to the holder of
this Warrant of a Convertible Promissory Note dated as of ____________, 199__
(the "Note"), for the principal amount of ___________________ dollars
($________).

        1. Purchase of Shares. Subject to the terms and conditions hereinafter
set forth and set forth in the Purchase Agreement, the holder of this Warrant is
entitled, upon surrender of this Warrant at the principal office of the Company
(or at such other place as the Company shall notify the holder hereof in
writing), to purchase from the Company up to that number of fully paid and
nonassessable shares of Preferred Stock of the Company, as more fully described
below, determined by dividing (a) the sum of (i) ten percent (10%) of the
aggregate amount of consideration provided by such Lender (i.e., the aggregate
amount paid for the related Note and this Warrant) and (ii) five percent (5%) of
the aggregate amount of consideration provided by such Lender (i.e., the
aggregate amount paid for the related Note and this Warrant) multiplied by the
number of full or partial months (based on a 30-day month) that the related Note
remains outstanding on and after April 1, 1999, by (b) the price per share of
equity securities sold to investors in the Company's next equity financing in
which the gross proceeds to the Company equal or exceed one million dollars
($1,000,000) (the "Next Equity Financing") or, in the event that the Company
fails to close such financing on or prior to September 30, 1999, by $4.37. The
Company currently anticipates that the securities issuable to investors in the
Next Equity Financing will be shares of Series E Preferred Stock. The Company
currently has no shares of Series E Preferred Stock authorized. Except as
otherwise provided herein, the class of capital stock or series of Preferred
Stock issuable upon exercise of this Warrant shall be the same class or series
as shall be issued in the Next Equity Financing, provided such Next Equity
Financing closes on or prior to September 30, 1999. Accordingly, if the Company
issues Series E Preferred Stock to the investors in the Next Equity Financing
and such financing closes



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on or prior to September 30, 1999, this Warrant shall be exercisable for shares
of the Company's Series E Preferred Stock. If the Company issues another series
of Preferred Stock or another class of capital stock to the investors in the
Next Equity Financing and such financing closes on or prior to September 30,
1999, this Warrant shall be exercisable for such other series of the Company's
Preferred Stock or such other class of the Company's capital stock, as the case
may be. If the Next Equity Financing closes after September 30, 1999, this
Warrant will be exercisable for shares of the Company's Series D Preferred
Stock. The shares of Preferred Stock issuable pursuant to this Section 1 (the
"Shares") shall also be subject to adjustment pursuant to Section 8 hereof. If
the securities issuable to investors in the Next Equity Financing are not
Preferred Stock, all references in this Warrant to "Preferred Stock" shall be
automatically deemed to be adjusted accordingly.

        2. Purchase Price. The purchase price for the Shares shall be the price
per share of equity securities sold to investors in the Company's Next Equity
Financing or, in the event that the Company fails to close the Next Equity
Financing on or prior to September 30, 1999, the purchase price for the Shares
shall be $4.37 per share. In either case, such price shall be subject to
adjustment pursuant to Section 8 hereof (such price, as adjusted from time to
time, is herein referred to as the "Exercise Price").

        3. Exercise Period. This Warrant shall become exercisable upon the
earlier of (i) the closing of the Next Equity Financing, (ii) September 30,
1999, or (iii) fifteen (15) days prior to either (A) the acquisition of the
Company by another entity by means of any transaction or series of related
transactions (including, without limitation, any reorganization, merger or
consolidation) that results in the transfer of fifty percent (50%) or more of
the outstanding voting power of the Company or (B) a sale of all or
substantially all of the assets of the Company, and this Warrant shall remain so
exercisable until and including December 31, 2003; provided, however, that in
the event of a proposed transaction of the kind described in (A) or (B) above,
this Warrant shall, on the date of such event, no longer be exercisable and
become null and void. In the event of a proposed transaction of the kind
described in (A) or (B) above, the Company shall notify the holder of the
Warrant at least fifteen (15) days prior to the consummation of such event or
transaction.

        4. Method of Exercise. While this Warrant remains outstanding and
exercisable in accordance with Section 3 above, the holder may exercise, in
whole or in part, the purchase rights evidenced hereby. Such exercise shall be
effected by:

            (i) the surrender of the Warrant, together with a duly executed copy
of the form of subscription attached hereto, to the Secretary of the Company at
its principal offices; and

            (ii) the payment to the Company of an amount equal to the aggregate
Exercise Price for the number of Shares being purchased.

        5. Net Exercise. In lieu of cash exercising this Warrant, the holder of
this Warrant may elect to receive shares equal to the value of this Warrant (or
the portion thereof being canceled) by surrender of this Warrant at the
principal office of the Company together with



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notice of such election, in which event the Company shall issue to the holder
hereof a number of shares of Preferred Stock computed using the following
formula:

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

               Where

               X -- The number of shares of Preferred Stock to be issued to
                    the holder of this Warrant.

               Y -- The number of shares of Preferred Stock purchasable under
                    this Warrant.

               A -- The fair market value of one share of the Company's
                    Preferred Stock.

               B -- The Exercise Price (as adjusted to the date of such
                    calculations).



        For purposes of this Paragraph 5, the fair market value of Preferred
Stock shall mean the average of the closing bid and asked prices of the
Preferred Stock quoted in the over-the-counter market in which the Preferred
Stock is traded or the closing price quoted on any exchange on which the
Preferred Stock is listed, whichever is applicable, as published in the Western
Edition of The Wall Street Journal for the ten (10) trading days prior to the
date of determination of fair market value (or such shorter period of time
during which such stock was traded over-the-counter or on such exchange). If the
Preferred Stock is not traded on the over-the-counter market or on an exchange,
the fair market value shall be the price per share that the Company could obtain
from a willing buyer for shares of Preferred Stock sold by the Company from
authorized but unissued shares, as such prices shall be determined in good faith
by the Company's Board of Directors.

        6. Certificates for Shares. Upon the exercise of the purchase rights
evidenced by this Warrant, one or more certificates for the number of Shares so
purchased shall be issued as soon as practicable thereafter, and in any event
within thirty (30) days of the delivery of the subscription notice.

        7. Issuance of Shares. The Company covenants that the Shares, when
issued pursuant to the exercise of this Warrant, will be duly and validly
issued, fully paid and nonassessable and free from all taxes, liens, and charges
with respect to the issuance thereof.

        8. Adjustment of Exercise Price and Number of Shares. The number of and
kind of securities purchasable upon exercise of this Warrant and the Exercise
Price shall be subject to adjustment from time to time as follows:

            (i) Subdivisions, Combinations and Other Issuances. If the Company
shall at any time prior to the expiration of this Warrant subdivide its
Preferred Stock, by split-up or otherwise, or combine its Preferred Stock, or
issue additional shares of its Preferred Stock or Common Stock as a dividend
with respect to any shares of its Preferred Stock, the number of Shares issuable
on the exercise of this Warrant shall forthwith be proportionately increased in
the



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case of a subdivision or stock dividend, or proportionately decreased in the
case of a combination. Appropriate adjustments shall also be made to the
purchase price payable per share, but the aggregate purchase price payable for
the total number of Shares purchasable under this Warrant (as adjusted) shall
remain the same. Any adjustment under this Section 8(a) shall become effective
at the close of business on the date the subdivision or combination becomes
effective, or as of the record date of such dividend, or in the event that no
record date is fixed, upon the making of such dividend.

            (ii) Reclassification, Reorganization and Consolidation. In case of
any reclassification, capital reorganization, or change in the Preferred Stock
of the Company (other than as a result of a subdivision, combination, or stock
dividend provided for in Section 8(a) above), then, as a condition of such
reclassification, reorganization or change, lawful provision shall be made, and
duly executed documents evidencing the same from the Company or its successor
shall be delivered to the holder of this Warrant, so that the holder of this
Warrant shall have the right at any time prior to the expiration of this Warrant
to purchase, at a total price equal to that payable upon the exercise of this
Warrant, the kind and amount of shares of stock and other securities and
property receivable in connection with such reclassification, reorganization, or
change by a holder of the same number of shares of Preferred Stock as were
purchasable by the holder of this Warrant immediately prior to such
reclassification, reorganization, or change. In any such case appropriate
provisions shall be made with respect to the rights and interest of the holder
of this Warrant so that the provisions hereof shall thereafter be applicable
with respect to any shares of stock or other securities and property deliverable
upon exercise hereof, and appropriate adjustments shall be made to the purchase
price per share payable hereunder, provided the aggregate purchase price shall
remain the same.

            (iii) Notice of Adjustment. When any adjustment is required to be
made in the number or kind of shares purchasable upon exercise of the Warrant,
or in the Warrant Price, the Company shall promptly notify the holder of such
event and of the number of shares of Preferred Stock or other securities or
property thereafter purchasable upon exercise of this Warrant.

        9.  No Fractional Shares or Scrip. No fractional shares or scrip
representing fractional shares shall be issued upon the exercise of this
Warrant, but in lieu of such fractional shares the Company shall make a cash
payment therefor on the basis of the Warrant Price then in effect.

        10. No Stockholder Rights. Prior to exercise of this Warrant, the holder
shall not be entitled to any rights of a stockholder with respect to the Shares,
including (without limitation) the right to vote such Shares, receive dividends
or other distributions thereon, exercise preemptive rights or be notified of
stockholder meetings, and such holder shall not be entitled to any notice or
other communication concerning the business or affairs of the Company.

        11. Successors and Assigns. The terms and provisions of this Warrant and
the Purchase Agreement shall inure to the benefit of, and be binding upon, the
Company and the holders hereof and their respective successors and assigns.



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        12. Amendments and Waivers. Any term of this Warrant may be amended and
the observance of any term of this Warrant may be waived (either generally or in
a particular instance and either retroactively or prospectively), with the
written consent of the Company and the holders of sixty percent (60%) of shares
of Preferred Stock issued or issuable upon exercise of Warrants issued pursuant
to the Purchase Agreement. Any waiver or amendment effected in accordance with
this Section shall be binding upon each holder of any Shares purchased under
this Warrant at the time outstanding (including securities into which such
Shares have been converted), each future holder of all such Shares, and the
Company.

        13. Effect of Amendment or Waiver. The holder of this Warrant
acknowledges that by the operation of paragraph 12 hereof, the holders of sixty
percent (60%) of shares of Preferred Stock issued or issuable upon exercise of
Warrants issued pursuant to the Purchase Agreement will have the right and power
to diminish or eliminate all rights of such holder under this Warrant or under
the Purchase Agreement.

        14. Governing Law. This Warrant shall be governed by the laws of the
State of California as applied to agreements among California residents made and
to be performed entirely within the State of California.

                                        OBJECTSWITCH CORPORATION



                                        By:
                                           -------------------------------------
                                           Paul Sutton
                                           President and Chief Executive Officer



                                        Address: 900 Larkspur Landing Circle
                                                 Suite 270
                                                 Larkspur, California 94939


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                                  SUBSCRIPTION



ObjectSwitch Corporation
Attention: Corporate Secretary

        The undersigned hereby elects to purchase, pursuant to the provisions of
the Warrant to Purchase Shares of Preferred Stock issued by ObjectSwitch
Corporation and held by the undersigned, shares of Preferred Stock of
ObjectSwitch Corporation.

        Payment of the exercise price per share required under such Warrant
accompanies this Subscription.

        The undersigned hereby represents and warrants that the undersigned is
acquiring such shares for its own account for investment purposes only, and not
for resale or with a view to distribution of such shares or any part thereof.


                                        WARRANTHOLDER:



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



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

Name in which shares should be registered:
                                          --------------------------------------



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