<PAGE>
                                                                     EXHIBIT 4.8

THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE SOLD, PLEDGED, OR
OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE REGISTRATION THEREOF UNDER SUCH ACT
OR PURSUANT TO RULE 144 OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO
THE CORPORATION AND ITS COUNSEL, THAT SUCH REGISTRATION IS NOT REQUIRED.


                            WARRANT TO PURCHASE STOCK

              Corporation: WIRELESS, INC., A CALIFORNIA CORPORATION
                         Number of Shares: 20,000 SHARES
                    Class of Stock: PREFERRED STOCK, SERIES E
                     Initial Exercise Price: $2.50 PER SHARE
                         Issue Date: SEPTEMBER 13, 1999
                       Expiration Date: SEPTEMBER 13, 2004

     THIS WARRANT CERTIFIES THAT, for the agreed upon value of $1.00 and for
other good and valuable consideration, SILICON VALLEY BANK ("Holder") is
entitled to purchase the number of fully paid and nonassessable shares of the
class of securities (the "Shares") of the corporation (the "Company") at the
initial exercise price per Share (the "Warrant Price") all as set forth above
and as adjusted pursuant to Article 2 of this Warrant, subject to the provisions
and upon the terms and conditions set forth in this Warrant.

ARTICLE 1. EXERCISE.

          1.1 METHOD OF EXERCISE. Holder may exercise this Warrant by delivering
a duly executed Nonce of Exercise in substantially the form attached as Appendix
1 to the principal office of the Company. Unless Holder is exercising the
conversion right set forth in Section 1.2, Holder shall also deliver to the
Company a check for the aggregate Warrant Price for the Shares being purchased.

          1.2 CONVERSION RIGHT. In lieu of exercising this Warrant as specified
in Section 1.1, Holder may from time to time convert this Warrant, in whole or
in part, into a number of Shares determined by dividing (a) the aggregate fair
market value of the Shares or other securities otherwise issuable upon exercise
of this Warrant minus the aggregate Warrant Price of such Shares by (b) the fair
market value of one Share. The fair market value of the Shares shall be
determined pursuant to Section 1.4.

          1.3 INTENTIONALLY OMITTED

          1.4 FAIR MARKET VALUE. If the Shares are traded in a public market,
the fair market value of the Shares shall be the closing price of the Shares (or
the closing price of the Company's stock into which the Shares are convertible)
reported for the business day immediately before Holder delivers its Notice of
Exercise to the Company. If the Shares are not


<PAGE>

traded in a public market, the Board of Directors of the Company shall determine
fair market value in its reasonable good faith judgment. The foregoing
notwithstanding, if Holder advises the Board of Directors in writing that Holder
disagrees with such determination, then the Company and Holder shall promptly
agree upon a reputable investment banking firm to undertake such valuation. If
the valuation of such investment banking firm is greater than that determined by
the Board of Directors, then all fees and expenses of such investment banking
firm shall be paid by the Company. In all other circumstances, such fees and
expenses shall be paid by Holder.

          1.5 DELIVERY OF CERTIFICATE AND NEW WARRANT. Promptly after Holder
exercises or converts this Warrant, the Company shall deliver to Holder
certificates for the Shares acquired and, if this Warrant has not been fully
exercised or converted and has not expired, a new Warrant representing the
Shares not so acquired.

          1.6 REPLACEMENT OF WARRANTS. On receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and, in the case of loss, theft or destruction, on delivery of an
indemnity agreement reasonably satisfactory in form and amount to the Company
or, in the case of mutilation, on surrender and cancellation of this Warrant,
the Company at its expense shall execute and deliver, in lieu of this Warrant, a
new warrant of like tenor.

          1.7 REPURCHASE ON SALE, MERGER, OR CONSOLIDATION OF THE COMPANY.

               1.7.1. "ACQUISITION". For the purpose of this Warrant,
"Acquisition" means any sale, license, or other disposition of all
or substantially all of the assets of the Company, or any reorganization,
consolidation, or merger of the Company where the holders of the Company's
securities before the transaction beneficially own less than 50% of the
outstanding voting securities of the surviving entity after the transaction.

               1.7.2. ASSUMPTION OF WARRANT. Upon the closing of any Acquisition
the successor entity shall assume the obligations of this Warrant, and this
Warrant shall be exercisable for the same 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. The Warrant Price shall be adjusted
accordingly.

               1.7.3. PURCHASE RIGHT. Notwithstanding the foregoing, at the
election of Holder, the Company shall purchase the unexercised portion of this
Warrant for cash upon the closing of any Acquisition for an amount equal to (a)
the fair marker value of any consideration that would have been received by
Holder in consideration of the Shares had Holder exercised the unexercised
portion of this Warrant immediately before the record date for determining the
shareholders entitled to participate in the proceeds of the Acquisition, less
(b) the aggregate Warrant Price of the Shares, but in no event less than zero.

ARTICLE 2. ADJUSTMENTS TO THE SHARES.


                                       2
<PAGE>

          2.1 STOCK DIVIDENDS, SPLITS, ETC. If the Company declares or
pays a dividend on its common stock (or the Shares if the Shares are securities
other than common stock) payable in common stock, or other securities,
subdivides the outstanding common stock into a greater amount of common stock,
or, if the Shares are securities other than common stock, subdivides, the Shares
in a transaction that increases the amount of common stock into which the Shares
are convertible, then upon exercise of this Warrant, for each Share acquired,
Holder shall receive, without cost to Holder, the total number and kind of
securities to which Holder would have been entitled had Holder owned the Shares
of record as of the date the dividend or subdivision occurred.

          2.2 RECLASSIFICATION, EXCHANGE OR SUBSTITUTION. Upon any
reclassification, exchange, substitution, or other event that results in a
change of the number and/or class of the securities issuable upon exercise or
conversion of this Warrant, Holder shall be entitled to receive, upon exercise
or conversion of this Warrant, the number and kind of securities and property
that Holder would have received for the Shares, if this Warrant had been
exercised immediately before such reclassification, exchange, substitution, or
other event. Such an event shall include any automatic conversion of the
outstanding or issuable securities of the Company of the same class or series as
the Shares to common stock pursuant to the terms of the Company's Articles of
Incorporation upon the closing of a registered public offering of the Company's
common stock. The Company or its successor shall promptly issue to Holder a new
Warrant for such new securities or other property. The new Warrant shall provide
for adjustments which shall be as nearly equivalent as may be practicable to the
adjustments provided for in this Article 2 including, without limitation,
adjustments to the Warrant Price, and to the number of securities or property
issuable upon exercise of the new Warrant. The provisions of this Section 2.2
shall similarly apply to successive reclassifications, exchanges, substitution,
or other events.

          2.3 ADJUSTMENTS FOR COMBINATIONS, ETC. If the outstanding Shares are
combined or consolidated by reclassification or otherwise, into a lesser number
of shares, the Warrant Price shall be proportionately increased.

          2.4 ADJUSTMENTS FOR DILUTING ISSUANCES. The Warrant Price and the
number of Shares issuable upon exercise of this Warrant or, if the Shares are
Preferred Stock, the number of shares of common stock issuable upon conversion
of the Shares, shall be subject to adjustment, from time to time in the manner
set forth on Exhibit A in the event of Diluting Issuances (as defined on Exhibit
A).


                                       3
<PAGE>

          2.5 NO IMPAIRMENT. The Company shall not, by amendment of its Articles
of Incorporation or through a reorganization, transfer of assets, consolidation,
merger, dissolution, issue, or sale of securities or any other voluntary action,
avoid or seek to avoid the observance or performance of any of the terms to be
observed or performed under this Warrant by the Company, but shall at all times
in good faith assist in carrying out of all the provisions of this Article 2 and
in taking all such action as may be necessary or appropriate to protect Holder's
rights under this Article against impairment. If the Company takes any action
affecting the Shares or its common stock other than as described above that
adversely affects Holder's rights under this Warrant, the Warrant Price shall be
adjusted downward and the number of Shares issuable upon exercise of this
Warrant shall be adjusted upward in such a manner that the aggregate Warrant
Price of this Warrant is unchanged.

          2.6 FRACTIONAL SHARES. No fractional Shares shall be issuable upon
exercise or conversion of the Warrant and the number of Shares to be issued
shall be rounded down to the nearest whole Share. If a fractional share interest
arises upon any exercise or conversion of the Warrant, the Company shall
eliminate such fractional share interest by paying Holder amount computed by
multiplying the fractional interest by the fair market value of a full Share.

          2.7 CERTIFICATE AS TO ADJUSTMENTS. Upon each adjustment of the Warrant
Price, the Company at its expense shall promptly compute such adjustment, and
furnish Holder with a certificate of its Chief Financial Officer setting forth
such adjustment and the facts upon which such adjustment is based. The Company
shall, upon written request, furnish Holder a certificate setting forth the
Warrant Price in effect upon the date thereof and the series of adjustments
leading to such Warrant Price.

ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY.

          3.1 REPRESENTATIONS AND WARRANTIES. The Company hereby represents and
warrants to the Holder as follows:

          (a) The initial Warrant Price referenced on the first page of this
Warrant is not greater than (i) the price per share at which the Shares were
last issued in an arms-length transaction in which at least $500,000 of the
Shares were sold and (ii) the fair market value of the Shares as of the date of
this Warrant.

               (b) All Shares which may be issued upon the exercise of the
purchase rights represented by this Warrant, and all securities, if any,
issuable upon conversion of the Shares, shall, upon issuance, be duly
authorized, validly issued, fully paid and nonassessable, and free of any liens
and encumbrances except for restrictions on transfer provided for herein or
under applicable federal and state securities laws.

               (c) The Capitalization Table attached to this Warrant is true and
complete as of the Issue Date.


                                       4
<PAGE>

          3.2 NOTICE OF CERTAIN EVENTS. If the Company proposes at any time (a)
to declare any dividend or distribution upon its common stock, whether in cash,
property, stock, or other securities and whether or not a regular cash dividend;
(b) to offer for subscription pro rata to the holders of any class or series of
its stock any additional shares of stock of any class or series or other rights;
(c) to effect any reclassification or recapitalization of common stock; (d) to
merge or consolidate with or into any other corporation, or sell, lease,
license, or convey, all or substantially all of its assets, or to liquidate,
dissolve or wind up; or (e) offer holders of registration rights the opportunity
to participate in an underwritten public offering of the company's securities
for cash, then, in connection with each such event, the Company shall give
Holder (1) at least 20 days prior written notice of the date on which a record
will be taken for such dividend, distribution, or subscription rights (and
specifying the date on which the holders of common stock will be entitled
thereto) or for determining rights to vote, if any, in respect of the matters
referred to in (c) and (d) above; (2) in the case of the matters referred to in
(c) and (d) above at least 20 days prior written notice of the date when the
same will take place (and specifying the date on which the holders of common
stock will be entitled to exchange their common stock for securities or other
property deliverable upon the occurrence of such event); and (3) in the case of
the matter referred to in (e) above, the same notice as is given to the holders
of such registration rights.

          3.3 INFORMATION RIGHTS. So long as the Holder holds this Warrant
and/or any of the Shares, the Company shall deliver to the Holder (a) promptly
after mailing, copies of all notices or other written communications to the
shareholders of the Company, (b) within ninety (90) days after the end of each
fiscal year of the Company, the annual audited financial statements of the
Company certified by independent public accountants of recognized standing and
(c) such other financial statements required under and in accordance with any
loan documents between Holder and the Company (or if there are no such
requirements [or if the subject loan(s) no longer are outstanding]), then within
forty-five (45) days after the end of each of the first three quarters of each
fiscal year, the Company's quarterly, unaudited financial statements.

          3.4 REGISTRATION UNDER SECURITIES ACT OF 1933, AS AMENDED. The Company
agrees that the Shares or, if the Shares are convertible into common stock of
the Company, such common stock, shall be subject to the registration rights set
forth on Exhibit B, if attached.

ARTICLE 4. MISCELLANEOUS.

          4.1 TERM; NOTICE OF EXPIRATION. This Warrant is exercisable, in whole
or in part, at any time and from time to time on or before the Expiration Date
set forth above. The Company shall give Holder written notice of Holder's right
to exercise this Warrant in the form attached as Appendix 2 not more than 90
days and not less than 30 days before the Expiration Date. If the notice is not
so given, the Expiration Date shall automatically be extended until 30 days
after the date the Company delivers the notice to Holder.

          4.2 LEGENDS. This Warrant and the Shares (and the securities issuable,
directly or indirectly, upon conversion of the Shares, if any) shall be
imprinted with a legend in substantially the following form:


                                       5
<PAGE>

     THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF I933, AS
     AMENDED, AND MAY NOT BE SOLD, PLEDGED OR OTHERWISE TRANSFERRED WITHOUT AN
     EFFECTIVE REGISTRATION THEREOF UNDER SUCH ACT OR PURSUANT TO RULE 144 OR AN
     OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE CORPORATION AND ITS
     COUNSEL THAT SUCH REGISTRATION IS NOT REQUIRED.

          4.3 COMPLIANCE WITH SECURITIES LAWS ON TRANSFER. This Warrant and the
Shares issuable upon exercise this Warrant (and the securities issuable,
directly or indirectly, upon conversion of the Shares, if any) may not be
transferred or assigned in whole or in part without compliance with applicable
federal and state securities laws by the transferor and the transferee
(including, without limitation, the delivery of investment representation
letters and legal opinions reasonably satisfactory to the Company, as reasonably
requested by the Company). The Company shall not require Holder to provide an
opinion of counsel if the transfer is to an affiliate of Holder or if there is
no material question as to the availability of current information as referenced
in Rule 144(c), Holder represents that it has complied with Rule 144(d) and (e)
in reasonable detail, the selling broker represents that it has complied with
Rule 144(f), and the Company is provided with a copy of Holder's notice of
proposed sale.

          4.4 TRANSFER PROCEDURE. Subject to the provisions of Section 4.3,
Holder may transfer all or part of this Warrant or the Shares issuable upon
exercise of this Warrant (or the securities issuable, directly or indirectly,
upon conversion of the Shares, if any) by giving the Company notice of the
portion of the Warrant being transferred setting forth the name, address and
taxpayer identification number of the transferee and surrendering the Warrant to
the Company for reissuance to the transferee(s) (and Holder, if applicable);
PROVIDED, HOWEVER, that Holder may transfer all or part of this Warrant to its
affiliates, including, without limitation, Silicon Valley Bancshares and The
Silicon Valley Bank Foundation, at any time without notice to the Company. The
terms and conditions of this Warrant shall inure to the benefit of, and be
binding upon, the Company and the holders hereof and their respective permitted
successors and assigns.

          4.5 NOTICES. All notices and other communications from the Company to
the Holder, or vice versa, shall be deemed delivered and effective when given
personally or mailed by first-class registered or certified mail, postage
prepaid, at such address as may have been furnished to the Company or the
Holder, as the case may be, in writing by the Company or such holder from time
to time. All notices to Holder should be sent to the following address:

               Treasury Department
               Silicon Valley Bank
               3003 Tasman Drive HG110
               Santa Clara, CA 95054


                                       6
<PAGE>



          4.6 WAIVER. This Warrant and any term hereof may be changed, waived,
discharged or terminated only by an instrument in writing signed by the party
against which enforcement of such change, waiver, discharge or termination is
sought.

          4.7 ATTORNEYS FEES. In the event of any dispute between the parties
concerning the terms and provisions of this Warrant, the party prevailing in
such dispute shall be entitled to collect from the other party all costs
incurred in such dispute, including reasonable attorneys' fees.

          4.8 GOVERNING LAW. This Warrant shall be governed by and construed in
accordance with the laws of the State of California, without giving effect to
its principles regarding conflicts of law.

                              "COMPANY"

                              WIRELESS, INC.

                              By:      /s/ WILLIAM E. GIBSON
                                       --------------------------------------

                              Name:
                                       --------------------------------------
                                       (Print)
                              Title:   Chairman of the Board, President or
                                       Vice President

                              By:      /s/ CHARLES PAI
                                       --------------------------------------

                              Name:    CHARLES PAI
                                       --------------------------------------
                                       (Print)
                              Title:   Chief  Financial  Officer,  Secretary,
                                       Assistant  Treasurer  or Assistant
                                       Secretary


                                       7
<PAGE>


                                   APPENDIX 1

                               NOTICE OF EXERCISE


     1. The undersigned hereby elects to purchase _____________ shares of the
Common/Series ________ Preferred [strike one] Stock of ________________________
pursuant to the terms of the attached Warrant, and tenders herewith payment of
the purchase price of such shares in full.

     1. The undersigned hereby elects to convert the attached Warrant into
Shares/cash [strike one] in the manner specified in the Warrant. This conversion
is exercised with respect to _______________________ of the Shares covered by
the Warrant.

     [Strike paragraph that does not apply.]

     2. Please issue a certificate or certificates representing said shares in
the name of the undersigned or in such other name as is specified below:


                    ------------------------------------------
                        (Name)


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

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

     3. The undersigned represents it is acquiring the shares solely for its
own account and not as a nominee for any other party and not with a view
toward the resale or distribution thereof except in compliance with applicable
securities laws.


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


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


<PAGE>


                                   APPENDIX 2

                     NOTICE THAT WARRANT IS ABOUT TO EXPIRE

                                _____________,__


(Name of Holder)

(Address of Holder)

Attn: Chief Financial Officer


Dear: _____________________

                                  This is to advise you that the Warrant issued
to you described below will expire on _____________________, 19__.

         Issuer:

         Issue Date:

         Class of Security Issuable:

         Exercise Price per Share:

         Number of Shares Issuable:

         Procedure for Exercise:

         Please contact [name of contact person at (phone number)] with any
questions you may have concerning exercise of the Warrant. This is your only
notice of pending expiration.

                                   -------------------------------------------
                                    (Name of Issuer)

                                    By:

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

                                    Its:

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


<PAGE>


                                    EXHIBIT A

                            Anti-Dilution Provisions

     In the event of the issuance (a "Diluting Issuance") by the Company, after
the Issue Date of the Warrant of securities at a price per share less than the
Warrant Price, or, if the Shares are common stock, less than the then conversion
price of the Company's Series ___ Preferred Stock, then the number of shares of
common stock issuable upon conversion of the Shares, or if the Shares are common
stock, the number of Shares issuable upon exercise of the Warrant, shall be
adjusted as a result of Diluting Issuances in accordance with the Holder's
standard form of Anti-Dilution Agreement in effect on the Issue Date.

     Under no circumstances shall the aggregate Warrant Price payable by the
Holder upon exercise of the Warrant increase as a result of any adjustment
arising from a Diluting Issuance.


<PAGE>


                               SILICON VALLEY BANK

                             ANTIDILUTION AGREEMENT

     THIS ANTIDILUTION AGREEMENT is entered into as of September 13, 1999, by
and between SILICON VALLEY BANK ("Purchaser") and Wireless, Inc.

                                    RECITALS

     A. Concurrently with the execution of this Antidilution Agreement, the
Purchaser is purchasing from the Company a Warrant to Purchase Stock (the
"Warrant")pursuant to which Purchaser has the right to acquire from the Company
the Shares (as defined in the Warrant).

     B. By this Antidilution Agreement, the Purchaser and the Company desire to
set forth the adjustment in the number of Shares issuable upon exercise of the
Warrant as a result of a Diluting Issuance (as defined in Exhibit A to the
Warrant).

     C. Capitalized terms used herein shall have the same meaning as set forth
in the Warrant.

          NOW, THEREFORE, in consideration of the mutual promises, covenants and
conditions hereinafter set forth, the parties hereto mutually agree as follows:

          1. DEFINITIONS. As used in this Antidilution Agreement, the following
terms have the following respective meanings:

               (a) "Option" means any right, option, or warrant to subscribe
for, purchase, or otherwise acquire common stock or Convertible Securities.

               (b) "Convertible Securities" means any evidences of indebtedness,
shares of stock, or other securities directly or indirectly convertible into or
exchangeable for common stock.

               (c) "Issue" means to grant, issue, sell, assume, or fix a record
date for determining persons entitled to receive, any security (including
Options), whichever of the foregoing is the first to occur.

               (d) "Additional Common Shares" means all common stock (including
reissued shares) issued (or deemed to be issued pursuant to Section 2) after the
date of the Warrant. Additional Common Shares does not include, however, any
common stock issued in a transaction described in Sections 2.1 and 2.2 of the
Warrant; any common stock Issued upon conversion of preferred stock outstanding
on the date of the Warrant; the Shares: or common stock Issued as incentive or
in a nonfinancing transaction to employees, officers, directors, or consultants
to the Company.


<PAGE>

     10.6 TITLES AND SUBTITLES. The titles of the sections [illegible]
Agreement are for convenience of reference only and are not to be
cons[illegible] Antidilution Agreement.

     10.7 COUNTERPARTS. This Antidiultion Agreement n[illegible]
number of counterparts, each of which shall be an original, but all [illegible]
constitute one instrument.

PURCHASER                          COMPANY

SILICON VALLEY BANK                WIRELESS, INC.

By:   /s/ Matthew Grignon          By: /s/ William E. Gibson
   ---------------------------        ------------------------------
Name: Matthew Grignon              Name:
     -------------------------          ----------------------------
      (print)                             (print)
Title:                             Title: Chairman of the Board, President or
      AVP                                 Vice President
------------------------------
Address: 3003 Tasman Drive         Address:
        ----------------------             -------------------------
         Santa Clara, CA
     -------------------------          ----------------------------
         95054
     -------------------------          ----------------------------

<PAGE>


                                    EXHIBIT B

                               REGISTRATION RIGHTS

     The Shares (if common stock), or the common stock issuable upon conversion
of the Shares, shall be deemed "registrable securities" or otherwise entitled to
"piggy back" registration rights in accordance with the terms of the following
agreement (the "Agreement") between the Company and its investor(s):


     --------------------------------------------------------
          [Identify Agreement by date, title and parties. If no
          Agreement exists, indicate by "none".]

     The Company agrees that no amendments will be made to the Agreement which
would have an adverse impact on Holder's registration rights thereunder without
the consent of Holder. By acceptance of the Warrant to which this Exhibit B is
attached. Holder shall be deemed to be a party to the Agreement, unless Holder
otherwise elects not to become or to cease being a party thereto.

     If no Agreement exists, then the Company and the Holder shall enter into
Holder's standard form of Registration Rights Agreement as in effect on the
Issue Date of the Warrant.