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                                                                   EXHIBIT 10.16

                                 METRICOM, INC.


                              AMENDED AND RESTATED
                          REGISTRATION RIGHTS AGREEMENT


                                NOVEMBER 15, 1999



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                                 METRICOM, INC.

                              AMENDED AND RESTATED
                          REGISTRATION RIGHTS AGREEMENT

        THIS AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT (the
"AGREEMENT") is entered into as November 15, 1999, by and among METRICOM, INC.,
a Delaware corporation (the "COMPANY") and holders of the Company's outstanding
securities listed on the Schedule of Investors attached hereto as Exhibit A
(collectively the "INVESTORS" and each individually as an "INVESTOR").


                                    RECITALS

        WHEREAS, the Company and certain of its security holders are parties to
a Registration Rights Agreement, originally dated as of June 23, 1986, as
amended to date (the "Original Registration Rights Agreement"); and

        WHEREAS, pursuant to a Preferred Stock Purchase Agreement dated as of
June 20, 1999 (the "Purchase Agreement"), the Company has sold and issued
30,000,000 shares of its Series A1 Preferred Stock to MCI Worldcom, Inc. and
30,000,000 shares of its Series A2 Preferred Stock to Vulcan Ventures
Incorporated; and

               WHEREAS, the Company and the holders of the requisite percentage
of Registrable Securities (as defined in the Original Registration Rights
Agreement) desire to amend the Original Registration Rights Agreement to permit
the Company to grant to MCI Worldcom, Inc. and Vulcan Ventures Incorporated
registration rights with respect to the shares purchased under the Purchase
Agreement, to revise Schedule A to the Original Registration Rights Agreement to
include only those holders and those holders' shares which are eligible for
registration rights as of the date first set forth above, to make certain other
changes to the Original Registration Rights Agreement and to restate the
Original Registration Rights Agreement in full;

        NOW, THEREFORE, in consideration of the mutual promises,
representations, warranties, covenants and conditions set forth in this
Agreement and in the Purchase Agreement, the parties mutually agree as follows:

                                    AGREEMENT

SECTION 1. GENERAL

        1.1 DEFINITIONS. As used in this Agreement the following terms shall
have the following respective meanings:

               "EXCHANGE ACT" means the Securities Exchange Act of 1934, as
amended.

               "FORM S-3" means such form under the Securities Act as in effect
on the date hereof or any successor registration form under the Securities Act
subsequently adopted by the



                                       1.
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SEC which permits inclusion or incorporation of substantial information by
reference to other documents filed by the Company with the SEC.

               "HOLDER" means any person owning of record Registrable Securities
that have not been sold to the public or any assignee of record of such
Registrable Securities in accordance with Section 2.10 hereof.

               "MAJOR HOLDER" means MCI WorldCom, Inc., Vulcan Ventures
Incorporated or any assignee of record of Registrable Securities held by either
of such Holders (in accordance with Section 2.10 hereof) that is an affiliate of
a Major Holder or holds at least twenty-five percent (25%) of the then
outstanding Registrable Securities.

               "REGISTER," "REGISTERED," and "REGISTRATION" refer to a
registration effected by preparing and filing a registration statement in
compliance with the Securities Act, and the declaration or ordering of
effectiveness of such registration statement or document.

               "REGISTRABLE SECURITIES" means (a) Common Stock of the Company
issued or issuable upon conversion of the Shares, (b) the shares of Common Stock
of the Company listed on Schedule A hereto that are issuable upon exercise of
certain warrants issued by the Company, and (c) Common Stock of the Company
issued as (or issuable upon the conversion or exercise of any warrant, right or
other security which is issued as) a dividend or other distribution with respect
to, or in exchange for or in replacement of, such above-described securities.
Notwithstanding the foregoing, Registrable Securities shall not include any
securities sold by a person to the public either pursuant to a registration
statement or Rule 144 or sold in a private transaction in which the transferor's
rights under Section 2 of this Agreement are not assigned.

               "REGISTRABLE SECURITIES THEN OUTSTANDING" shall be the number of
shares determined by calculating the total number of shares of the Company's
Common Stock that are Registrable Securities and either (a) are then issued and
outstanding or (b) are issuable pursuant to then exercisable or convertible
securities.

               "REGISTRATION EXPENSES" shall mean all expenses incurred by the
Company in complying with Sections 2.2, 2.3 and 2.4 hereof, including, without
limitation, all registration and filing fees, printing expenses, fees and
disbursements of counsel for the Company, reasonable fees and disbursements not
to exceed twenty-five thousand dollars ($25,000) of a single special counsel for
the Holders, blue sky fees and expenses and the expense of any special audits
incident to or required by any such registration (but excluding the compensation
of regular employees of the Company which shall be paid in any event by the
Company).

               "SEC" or "COMMISSION" means the Securities and Exchange
Commission.

               "SECURITIES ACT" shall mean the Securities Act of 1933, as
amended.

               "SELLING EXPENSES" shall mean all underwriting discounts and
selling commissions applicable to the sale.

               "SHARES" shall mean the Company's Series A1 Preferred Stock and
Series A2 Preferred Stock issued pursuant to the Purchase Agreement.



                                       2.
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SECTION 2. REGISTRATION; RESTRICTIONS ON TRANSFER

        2.1 RESTRICTIONS ON TRANSFER.

               (a) Each Holder agrees not to make any disposition of all or any
portion of the Shares or Registrable Securities unless and until:

                    (i) There is then in effect a registration statement under
the Securities Act covering such proposed disposition and such disposition is
made in accordance with such registration statement; or

                    (ii) (A) The transferee has agreed in writing to be bound by
the terms of this Agreement, (B) such Holder shall have notified the Company of
the proposed disposition and shall have furnished the Company with a detailed
statement of the circumstances surrounding the proposed disposition, and (C) if
reasonably requested by the Company, such Holder shall have furnished the
Company with an opinion of counsel, reasonably satisfactory to the Company, that
such disposition will not require registration of such shares under the
Securities Act. It is agreed that the Company will not require opinions of
counsel for transactions made pursuant to Rule 144 except in unusual
circumstances.

                    (iii) Notwithstanding the provisions of paragraphs (i) and
(ii) above, no such registration statement or opinion of counsel shall be
necessary for a transfer by a Holder which is (A) a partnership to its partners
or former partners in accordance with partnership interests, (B) a corporation
to its shareholders in accordance with their interest in the corporation, (C) a
limited liability company to its members or former members in accordance with
their interest in the limited liability company, or (D) to the Holder's family
member or trust for the benefit of an individual Holder; provided that in each
case the transferee will be subject to the terms of this Agreement to the same
extent as if he were an original Holder hereunder.

               (b) Each certificate representing Shares or Registrable
Securities shall (unless otherwise permitted by the provisions of the Agreement)
be stamped or otherwise imprinted with a legend substantially similar to the
following (in addition to any legend required under applicable state securities
laws):

               "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
               REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR THE
               SECURITIES LAWS OF ANY STATE AND MAY NOT BE SOLD, TRANSFERRED OR
               OTHERWISE DISPOSED OF UNLESS THEY ARE SO REGISTERED OR UNLESS AN
               EXEMPTION FROM REGISTRATION IS AVAILABLE."

               (c) The Company shall be obligated to reissue promptly unlegended
certificates at the request of any holder thereof if the holder shall have
obtained an opinion of counsel (which counsel may be counsel to the Company)
reasonably acceptable to the Company to the effect that the securities proposed
to be disposed of may lawfully be so disposed of without registration,
qualification or legend.



                                       3.
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               (d) Any legend endorsed on an instrument pursuant to applicable
state securities laws and the stop-transfer instructions with respect to such
securities shall be removed upon receipt by the Company of an order of the
appropriate blue sky authority authorizing such removal.

        2.2 DEMAND REGISTRATION.

               (a) Subject to the conditions of this Section 2.2, if the Company
shall receive a written request from either (i) one or more of the Major Holders
or (ii) Holders who in the aggregate hold at least 500,000 shares of Registrable
Securities (the "INITIATING HOLDERS"), that the Company file a registration
statement under the Securities Act covering the registration of Registrable
Securities the anticipated aggregate offering price of which, net of
underwriting discounts and commissions, would exceed $10,000,000 (a "QUALIFIED
PUBLIC OFFERING"), then the Company shall, within thirty (30) days of the
receipt thereof, give written notice of such request to all Holders and, subject
to the limitations of this Section 2.2, use its best efforts to effect, as soon
as practicable, the registration under the Securities Act of all Registrable
Securities that the Initiating Holders request to be registered.

               (b) If the Initiating Holders intend to distribute the
Registrable Securities covered by their request by means of an underwriting,
they shall so advise the Company as a part of their request made pursuant to
this Section 2.2 or any request pursuant to Section 2.4 and the Company shall
include such information in the written notice referred to in Section 2.2(a) or
Section 2.4(a), as applicable. In such event, the right of any Holder to include
its Registrable Securities in such registration shall be conditioned upon such
Holder's participation in such underwriting and the inclusion of such Holder's
Registrable Securities in the underwriting to the extent provided herein. All
Holders proposing to distribute their securities through such underwriting shall
enter into an underwriting agreement in customary form with the underwriter or
underwriters selected for such underwriting by a majority in interest of the
Initiating Holders (which underwriter or underwriters shall be reasonably
acceptable to the Company). Notwithstanding any other provision of this Section
2.2 or Section 2.4, if the underwriter advises the Company that marketing
factors require a limitation of the number of securities to be underwritten
(including Registrable Securities) then the Company shall so advise all Holders
of Registrable Securities which would otherwise be underwritten pursuant hereto,
and the number of shares that may be included in the underwriting shall be
allocated to the Holders of such Registrable Securities on a pro rata basis
based on the number of Registrable Securities held by all such Holders
(including the Initiating Holders); provided, however, that:

                    (i) the number of shares of Registrable Securities to be
included in such underwriting and registration on behalf of Initiating Holders
that are Major Holders shall not be subject to reduction pursuant to this
Section 2.2(b); and

                    (ii) the number of shares of Registrable Securities to be
included in such underwriting and registration shall not be reduced unless all
other securities of the Company are first entirely excluded from the
underwriting and registration.

Any Registrable Securities excluded or withdrawn from such underwriting shall be
withdrawn from the registration.



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               (c) The Company shall not be required to effect a registration
pursuant to this Section 2.2:

                    (i) after the Company has effected two (2) registrations
pursuant to this Section 2.2 and such registrations have been declared or
ordered effective; provided, however, that this subsection (i) shall not apply
to any registration for which the Initiating Holders include one or more of the
Major Holders;

                    (ii) if the Company shall furnish to Holders requesting a
registration statement pursuant to this Section 2.2, a certificate signed by the
Chairman of the Board stating that in the good faith judgment of the Board of
Directors of the Company, it would be seriously detrimental to the Company and
its shareholders for such registration statement to be effected at such time, in
which event the Company shall have the right to defer such filing for a period
of not more than one hundred twenty (120) days after receipt of the request of
the Initiating Holders; provided that such right to delay a request shall be
exercised by the Company not more than once in any twelve (12) month period; or

                    (iii) if the Initiating Holders propose to dispose of shares
of Registrable Securities that are then eligible to be registered on Form S-3
pursuant to a request made pursuant to Section 2.4 below; provided, however,
that this subsection (iii) shall not apply to any registration for which the
Initiating Holders include one or more of the Major Holders.

        2.3 PIGGYBACK REGISTRATIONS. The Company shall notify all Holders of
Registrable Securities in writing at least fifteen (15) days prior to the filing
of any registration statement under the Securities Act for purposes of a public
offering of securities of the Company (including, but not limited to,
registration statements relating to secondary offerings of securities of the
Company, but excluding registration statements relating to employee benefit
plans or with respect to corporate reorganizations or other transactions under
Rule 145 of the Securities Act) and will afford each such Holder an opportunity
to include in such registration statement all or part of such Registrable
Securities held by such Holder. Each Holder desiring to include in any such
registration statement all or any part of the Registrable Securities held by it
shall, within fifteen (15) days after the above-described notice from the
Company, so notify the Company in writing. Such notice shall state the intended
method of disposition of the Registrable Securities by such Holder. If a Holder
decides not to include all of its Registrable Securities in any registration
statement thereafter filed by the Company, such Holder shall nevertheless
continue to have the right to include any Registrable Securities in any
subsequent registration statement or registration statements as may be filed by
the Company with respect to offerings of its securities, all upon the terms and
conditions set forth herein.

               (a) UNDERWRITING. If the registration statement under which the
Company gives notice under this Section 2.3 is for an underwritten offering, the
Company shall so advise the Holders of Registrable Securities. In such event,
the right of any such Holder to be included in a registration pursuant to this
Section 2.3 shall be conditioned upon such Holder's participation in such
underwriting and the inclusion of such Holder's Registrable Securities in the
underwriting to the extent provided herein. All Holders proposing to distribute
their Registrable Securities through such underwriting shall enter into an
underwriting agreement in customary form with the underwriter or underwriters
selected for such underwriting by the



                                       5.
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Company. Notwithstanding any other provision of the Agreement, if the
underwriter determines in good faith that marketing factors require a limitation
of the number of shares to be underwritten, the number of shares that may be
included in the underwriting shall be allocated, first, to the Company; second,
to the Holders on a pro rata basis based on the total number of Registrable
Securities held by the Holders; and third, to any shareholder of the Company
(other than a Holder) on a pro rata basis. No such reduction shall (i) reduce
the securities being offered by the Company for its own account to be included
in the registration and underwriting, or (ii) reduce the amount of securities of
the selling Holders included in the registration below twenty-five percent (25%)
of the total amount of securities included in such registration. If any Holder
disapproves of the terms of any such underwriting, such Holder may elect to
withdraw therefrom by written notice to the Company and the underwriter,
delivered at least ten (10) business days prior to the effective date of the
registration statement. Any Registrable Securities excluded or withdrawn from
such underwriting shall be excluded and withdrawn from the registration. For any
Holder which is a partnership or corporation, the partners, retired partners and
shareholders of such Holder, or the estates and family members of any such
partners and retired partners and any trusts for the benefit of any of the
foregoing person shall be deemed to be a single "HOLDER", and any pro rata
reduction with respect to such "Holder" shall be based upon the aggregate amount
of shares carrying registration rights owned by all entities and individuals
included in such "Holder," as defined in this sentence.

               (b) RIGHT TO TERMINATE REGISTRATION. The Company shall have the
right to terminate or withdraw any registration initiated by it under this
Section 2.3 prior to the effectiveness of such registration whether or not any
Holder has elected to include securities in such registration. The Registration
Expenses of such withdrawn registration shall be borne by the Company in
accordance with Section 2.5 hereof.

        2.4 FORM S-3 REGISTRATION. In case the Company shall receive from any
Holder or Holders of Registrable Securities a written request or requests that
the Company effect a registration on Form S-3 (or any successor to Form S-3) or
any similar short-form registration statement and any related qualification or
compliance with respect to all or a part of the Registrable Securities owned by
such Holder or Holders, the Company will:

               (a) promptly give written notice of the proposed registration,
and any related qualification or compliance, to all other Holders of Registrable
Securities; and

               (b) as soon as practicable, effect such registration and all such
qualifications and compliances as may be so requested and as would permit or
facilitate the sale and distribution of all or such portion of such Holder's or
Holders' Registrable Securities as are specified in such request, together with
all or such portion of the Registrable Securities of any other Holder or Holders
joining in such request as are specified in a written request given within
fifteen (15) days after receipt of such written notice from the Company;
provided, however, that the Company shall not be obligated to effect any such
registration, qualification or compliance pursuant to this Section 2.4:

                    (i) if Form S-3 (or any successor or similar form) is not
available for such offering by the Holders;



                                       6.
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                    (ii) if the Holders, together with the holders of any other
securities of the Company entitled to inclusion in such registration, propose to
sell Registrable Securities and such other securities (if any) at an aggregate
price to the public of less than one million dollars ($1,000,000);

                    (iii) if within thirty (30) days of receipt of a written
request from any Holder or Holders pursuant to this Section 2.4, the Company
gives notice to such Holder or Holders of the Company's intention to make a
public offering within ninety (90) days;

                    (iv) if the Company shall furnish to the Holders a
certificate signed by the Chairman of the Board of Directors of the Company
stating that in the good faith judgment of the Board of Directors of the
Company, it would be seriously detrimental to the Company and its shareholders
for such Form S-3 registration to be effected at such time, in which event the
Company shall have the right to defer the filing of the Form S-3 registration
statement for a period of not more than ninety (90) days after receipt of the
request of the Holder or Holders under this Section 2.4; provided, that such
right to delay a request shall be exercised by the Company not more than twice
in any twelve (12) month period, or

                    (v) if the Company has, within the twelve (12) month period
preceding the date of such request, already effected two (2) registrations on
Form S-3 for the Holders pursuant to this Section 2.4 (unless the registration
is requested by one or more of the Major Holders, in which case the Company
shall not be excused from effecting such registration under this subsection
unless it has, within the twelve (12) month period preceding the date of such
request, already effected one (1) or more registrations requested by such Major
Holder(s) under Section 2.2 or this Section 2.4), or

                    (vi) in any particular jurisdiction in which the Company
would be required to qualify to do business or to execute a general consent to
service of process in effecting such registration, qualification or compliance.

               (c) Subject to the foregoing, the Company shall file a Form S-3
registration statement covering the Registrable Securities and other securities
so requested to be registered as soon as practicable after receipt of the
request or requests of the Holders. Registrations effected pursuant to this
Section 2.4 shall not be counted as demands for registration or registrations
effected pursuant to Sections 2.2 or 2.3, respectively.

        2.5 EXPENSES OF REGISTRATION. Except as specifically provided herein,
all Registration Expenses incurred in connection with any registration,
qualification or compliance pursuant to Section 2.2 or any registration under
Section 2.3 or Section 2.4 herein shall be borne by the Company. All such
Registration Expenses incurred in connection with registrations requested
pursuant to Section 2.4 (other than registrations requested by one or more Major
Holders) after the first two (2) registrations shall be paid by the selling
Holders pro rata in proportion to the number of shares sold by each. All Selling
Expenses incurred in connection with any registrations hereunder, shall be borne
by the holders of the securities so registered pro rata on the basis of the
number of shares so registered. The Company shall not, however, be required to
pay for expenses of any registration proceeding begun pursuant to Section 2.2 or
2.4, the request of which has been subsequently withdrawn by the Initiating
Holders unless (a) the



                                       7.
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withdrawal is based upon material adverse information concerning the Company of
which the Initiating Holders were not aware at the time of such request or (b)
the Holders of a majority of Registrable Securities agree to forfeit their right
to one requested registration pursuant to Section 2.2 or Section 2.4, as
applicable, in which event such right shall be forfeited by all Holders). If the
Holders are required to pay the Registration Expenses, such expenses shall be
borne by the holders of securities (including Registrable Securities) requesting
such registration in proportion to the number of shares for which registration
was requested. If the Company is required to pay the Registration Expenses of a
withdrawn offering pursuant to clause (a) above, then the Holders shall not
forfeit their rights pursuant to Section 2.2 or Section 2.4 to a demand
registration.

        2.6 OBLIGATIONS OF THE COMPANY. Whenever required to effect the
registration of any Registrable Securities, the Company shall, as expeditiously
as reasonably possible:

               (a) Prepare and file with the SEC a registration statement with
respect to such Registrable Securities and use all reasonable efforts to cause
such registration statement to become effective, and, upon the request of the
Holders of a majority of the Registrable Securities registered thereunder, keep
such registration statement effective for up to thirty (30) days or, if earlier,
until the Holder or Holders have completed the distribution related thereto. The
Company shall not be required to file, cause to become effective or maintain the
effectiveness of any registration statement that contemplates a distribution of
securities on a delayed or continuous basis pursuant to Rule 415 under the
Securities Act.

               (b) Prepare and file with the SEC such amendments and supplements
to such registration statement and the prospectus used in connection with such
registration statement as may be necessary to comply with the provisions of the
Securities Act with respect to the disposition of all securities covered by such
registration statement for the period set forth in paragraph (a) above.

               (c) Furnish to the Holders such number of copies of a prospectus,
including a preliminary prospectus, in conformity with the requirements of the
Securities Act, and such other documents as they may reasonably request in order
to facilitate the disposition of Registrable Securities owned by them.

               (d) Use its reasonable best efforts to register and qualify the
securities covered by such registration statement under such other securities or
Blue Sky laws of such jurisdictions as shall be reasonably requested by the
Holders; provided that the Company shall not be required in connection therewith
or as a condition thereto to qualify to do business or to file a general consent
to service of process in any such states or jurisdictions.

               (e) In the event of any underwritten public offering, enter into
and perform its obligations under an underwriting agreement, in usual and
customary form, with the managing underwriter(s) of such offering. Each Holder
participating in such underwriting shall also enter into and perform its
obligations under such an agreement.

               (f) Notify each Holder of Registrable Securities covered by such
registration statement at any time when a prospectus relating thereto is
required to be delivered under the Securities Act of the happening of any event
as a result of which the prospectus included in such



                                       8.
<PAGE>   10

registration statement, as then in effect, includes an untrue statement of a
material fact or omits to state a material fact required to be stated therein or
necessary to make the statements therein not misleading in the light of the
circumstances then existing.

               (g) Use its best efforts to furnish, on the date that such
Registrable Securities are delivered to the underwriters for sale, if such
securities are being sold through underwriters, (i) an opinion, dated as of such
date, of the counsel representing the Company for the purposes of such
registration, in form and substance as is customarily given to underwriters in
an underwritten public offering, addressed to the underwriters, if any, and (ii)
a letter dated as of such date, from the independent certified public
accountants of the Company, in form and substance as is customarily given by
independent certified public accountants to underwriters in an underwritten
public offering addressed to the underwriters.

        2.7 TERMINATION OF REGISTRATION RIGHTS. All registration rights granted
under this Section 2 to Holders other than Major Holders shall terminate on
December 31, 2001 and shall thereafter be of no further force or effect. In
addition, a Holder's registration rights shall expire if all Registrable
Securities held by and issuable to such Holder (and such Holder's affiliates,
partners, former partners, members and former members) may be sold under Rule
144 (including paragraph (k) thereof) during any ninety (90) day period.

        2.8 DELAY OF REGISTRATION; FURNISHING INFORMATION.

               (a) No Holder shall have any right to obtain or seek an
injunction restraining or otherwise delaying any such registration as the result
of any controversy that might arise with respect to the interpretation or
implementation of this Section 2.

               (b) It shall be a condition precedent to the obligations of the
Company to take any action pursuant to Section 2.2, 2.3 or 2.4 that the selling
Holders shall furnish to the Company such information regarding themselves, the
Registrable Securities held by them and the intended method of disposition of
such securities as shall be required to effect the registration of their
Registrable Securities.

               (c) The Company shall have no obligation with respect to any
registration requested pursuant to Section 2.2 or Section 2.4 if, due to the
operation of subsection 2.2(b), the number of shares or the anticipated
aggregate offering price of the Registrable Securities to be included in the
registration does not equal or exceed the number of shares or the anticipated
aggregate offering price required to originally trigger the Company's obligation
to initiate such registration as specified in Section 2.2 or Section 2.4,
whichever is applicable.

        2.9 INDEMNIFICATION. In the event any Registrable Securities are
included in a registration statement under Sections 2.2, 2.3 or 2.4:

               (a) To the extent permitted by law, the Company will indemnify
and hold harmless each Holder, the partners, officers and directors of each
Holder, any underwriter (as defined in the Securities Act) for such Holder and
each person, if any, who controls such Holder or underwriter within the meaning
of the Securities Act or the Exchange Act, against any losses, claims, damages,
or liabilities (joint or several) to which they may become subject under the
Securities Act, the Exchange Act or other federal or state law, insofar as such
losses, claims,



                                       9.
<PAGE>   11

damages or liabilities (or actions in respect thereof) arise out of or are based
upon any of the following statements, omissions or violations (collectively a
"VIOLATION") by the Company: (i) any untrue statement or alleged untrue
statement of a material fact contained in such registration statement, including
any preliminary prospectus or final prospectus contained therein or any
amendments or supplements thereto, (ii) the omission or alleged omission to
state therein a material fact required to be stated therein, or necessary to
make the statements therein not misleading, or (iii) any violation or alleged
violation by the Company of the Securities Act, the Exchange Act, any state
securities law or any rule or regulation promulgated under the Securities Act,
the Exchange Act or any state securities law in connection with the offering
covered by such registration statement; and the Company will pay as incurred to
each such Holder, partner, officer, director, underwriter or controlling person
for any legal or other expenses reasonably incurred by them in connection with
investigating or defending any such loss, claim, damage, liability or action;
provided however, that the indemnity agreement contained in this Section 2.9(a)
shall not apply to amounts paid in settlement of any such loss, claim, damage,
liability or action if such settlement is effected without the consent of the
Company, which consent shall not be unreasonably withheld, nor shall the Company
be liable in any such case for any such loss, claim, damage, liability or action
to the extent that it arises out of or is based upon a Violation which occurs in
reliance upon and in conformity with written information furnished expressly for
use in connection with such registration by such Holder, partner, officer,
director, underwriter or controlling person of such Holder.

               (b) To the extent permitted by law, each Holder will, if
Registrable Securities held by such Holder are included in the securities as to
which such registration qualifications or compliance is being effected,
indemnify and hold harmless the Company, each of its directors, its officers and
each person, if any, who controls the Company within the meaning of the
Securities Act, any underwriter and any other Holder selling securities under
such registration statement or any of such other Holder's partners, directors or
officers or any person who controls such Holder, against any losses, claims,
damages or liabilities (joint or several) to which the Company or any such
director, officer, controlling person, underwriter or other such Holder, or
partner, director, officer or controlling person of such other Holder may become
subject under the Securities Act, the Exchange Act or other federal or state
law, insofar as such losses, claims, damages or liabilities (or actions in
respect thereto) arise out of or are based upon any Violation, in each case to
the extent (and only to the extent) that such Violation occurs in reliance upon
and in conformity with written information furnished by such Holder under an
instrument duly executed by such Holder and stated to be specifically for use in
connection with such registration; and each such Holder will pay as incurred any
legal or other expenses reasonably incurred by the Company or any such director,
officer, controlling person, underwriter or other Holder, or partner, officer,
director or controlling person of such other Holder in connection with
investigating or defending any such loss, claim, damage, liability or action if
it is judicially determined that there was such a Violation; provided, however,
that the indemnity agreement contained in this Section 2.9(b) shall not apply to
amounts paid in settlement of any such loss, claim, damage, liability or action
if such settlement is effected without the consent of the Holder, which consent
shall not be unreasonably withheld; provided further, that in no event shall any
indemnity under this Section 2.9 exceed the net proceeds from the offering
received by such Holder.



                                      10.
<PAGE>   12

               (c) Promptly after receipt by an indemnified party under this
Section 2.9 of notice of the commencement of any action (including any
governmental action), such indemnified party will, if a claim in respect thereof
is to be made against any indemnifying party under this Section 2.9, deliver to
the indemnifying party a written notice of the commencement thereof and the
indemnifying party shall have the right to participate in, and, to the extent
the indemnifying party so desires, jointly with any other indemnifying party
similarly noticed, to assume the defense thereof with counsel mutually
satisfactory to the parties; provided, however, that an indemnified party shall
have the right to retain its own counsel, with the fees and expenses to be paid
by the indemnifying party, if representation of such indemnified party by the
counsel retained by the indemnifying party would be inappropriate due to actual
or potential differing interests between such indemnified party and any other
party represented by such counsel in such proceeding. The failure to deliver
written notice to the indemnifying party within a reasonable time of the
commencement of any such action, if materially prejudicial to its ability to
defend such action, shall relieve such indemnifying party of any liability to
the indemnified party under this Section 2.9, but the omission so to deliver
written notice to the indemnifying party will not relieve it of any liability
that it may have to any indemnified party otherwise than under this Section 2.9.

               (d) If the indemnification provided for in this Section 2.9 is
held by a court of competent jurisdiction to be unavailable to an indemnified
party with respect to any losses, claims, damages or liabilities referred to
herein, the indemnifying party, in lieu of indemnifying such indemnified party
thereunder, shall to the extent permitted by applicable law contribute to the
amount paid or payable by such indemnified party as a result of such loss,
claim, damage or liability in such proportion as is appropriate to reflect the
relative fault of the indemnifying party on the one hand and of the indemnified
party on the other in connection with the Violation(s) that resulted in such
loss, claim, damage or liability, as well as any other relevant equitable
considerations. The relative fault of the indemnifying party and of the
indemnified party shall be determined by a court of law by reference to, among
other things, whether the untrue or alleged untrue statement of a material fact
or the omission to state a material fact relates to information supplied by the
indemnifying party or by the indemnified party and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
statement or omission; provided, that in no event shall any contribution by a
Holder hereunder exceed the net proceeds from the offering received by such
Holder.

               (e) The obligations of the Company and Holders under this Section
2.9 shall survive completion of any offering of Registrable Securities in a
registration statement and the termination of this agreement. No Indemnifying
Party, in the defense of any such claim or litigation, shall, except with the
consent of each Indemnified Party, consent to entry of any judgment or enter
into any settlement which does not include as an unconditional term thereof the
giving by the claimant or plaintiff to such Indemnified Party of a release from
all liability in respect to such claim or litigation.

        2.10 ASSIGNMENT OF REGISTRATION RIGHTS. The rights to cause the Company
to register Registrable Securities pursuant to this Section 2 may be assigned by
a Holder to a transferee or assignee of Registrable Securities which (a) is a
subsidiary, parent, general partner, limited partner, retired partner, member or
retired member of a Holder, (b) is an affiliate of a Major Holder, (c) is a
Holder's family member or trust for the benefit of an individual Holder, or (d)



                                      11.
<PAGE>   13

acquires at least fifty thousand (50,000) shares of Registrable Securities (as
adjusted for stock splits and combinations); provided, however, (i) the
transferor shall, within ten (10) days after such transfer, furnish to the
Company written notice of the name and address of such transferee or assignee
and the securities with respect to which such registration rights are being
assigned and (ii) such transferee shall agree to be subject to all restrictions
set forth in this Agreement.

        2.11 AMENDMENT OF REGISTRATION RIGHTS. Any provision of this Section 2
may be amended and the observance thereof may be waived (either generally or in
a particular instance and either retroactively or prospectively), only with the
written consent of the Company, the Major Holders and the Holders of at least
two-thirds (2/3) of the Registrable Securities then outstanding. Any amendment
or waiver effected in accordance with this Section 2.11 shall be binding upon
each Holder and the Company. By acceptance of any benefits under this Section 2,
Holders of Registrable Securities hereby agree to be bound by the provisions
hereunder.

        2.12 LIMITATION ON SUBSEQUENT REGISTRATION RIGHTS. After the date of
this Agreement, the Company shall not, without the prior written consent of the
Holders of at least two-thirds (2/3) of the Registrable Securities then
outstanding, enter into any agreement with any holder or prospective holder of
any securities of the Company that would grant such holder registration rights
pari passu or senior to those granted to the Holders hereunder.

        2.13 "MARKET STAND-OFF" AGREEMENT; AGREEMENT TO FURNISH INFORMATION.

               (a) Each Holder hereby agrees that such Holder shall not sell,
transfer, make any short sale of, grant any option for the purchase of, or enter
into any hedging or similar transaction with the same economic effect as a sale,
any Common Stock (or other securities) of the Company held by such Holder (other
than those included in the registration) for a period specified by the
representative of the underwriters of Common Stock (or other securities) of the
Company not to exceed ninety (90) days following the effective date of a
registration statement of the Company filed under the Securities Act; provided
that all officers and directors of the Company enter into similar agreements.

               (b) Each Holder agrees to execute and deliver such other
agreements as may be reasonably requested by the Company or the underwriter
which are consistent with the foregoing or which are necessary to give further
effect thereto. In addition, if requested by the Company or the representative
of the underwriters of Common Stock (or other securities) of the Company, each
Holder shall provide, within ten (10) days of such request, such information as
may be required by the Company or such representative in connection with the
completion of any public offering of the Company's securities pursuant to a
registration statement filed under the Securities Act. The obligations described
in this Section 2.13 shall not apply to a registration relating solely to
employee benefit plans on Form S-1 or Form S-8 or similar forms that may be
promulgated in the future, or a registration relating solely to a Commission
Rule 145 transaction on Form S-4 or similar forms that may be promulgated in the
future. The Company may impose stop-transfer instructions with respect to the
shares of Common Stock (or other securities) subject to the foregoing
restriction until the end of said ninety (90) day period.



                                      12.
<PAGE>   14

        2.14 RULE 144 REPORTING. With a view to making available to the Holders
the benefits of certain rules and regulations of the SEC which may permit the
sale of the Registrable Securities to the public without registration, the
Company agrees to use its best efforts to:

               (a) Make and keep public information available, as those terms
are understood and defined in SEC Rule 144 or any similar or analogous rule
promulgated under the Securities Act, at all times after the effective date of
the first registration filed by the Company for an offering of its securities to
the general public;

               (b) File with the SEC, in a timely manner, all reports and other
documents required of the Company under the Exchange Act; and

               (c) So long as a Holder owns any Registrable Securities, furnish
to such Holder forthwith upon request: a written statement by the Company as to
its compliance with the reporting requirements of said Rule 144 of the
Securities Act, and of the Exchange Act (at any time after it has become subject
to such reporting requirements); a copy of the most recent annual or quarterly
report of the Company; and such other reports and documents as a Holder may
reasonably request in availing itself of any rule or regulation of the SEC
allowing it to sell any such securities without registration.

SECTION 3. MISCELLANEOUS

        3.1 GOVERNING LAW. This Agreement shall be governed by and construed
under the laws of the State of California as applied to agreements among
California residents entered into and to be performed entirely within
California.

        3.2 SURVIVAL. The representations, warranties, covenants, and agreements
made herein shall survive any investigation made by any Holder and the closing
of the transactions contemplated hereby. All statements as to factual matters
contained in any certificate or other instrument delivered by or on behalf of
the Company pursuant hereto in connection with the transactions contemplated
hereby shall be deemed to be representations and warranties by the Company
hereunder solely as of the date of such certificate or instrument.

        3.3 SUCCESSORS AND ASSIGNS. Except as otherwise expressly provided
herein, the provisions hereof shall inure to the benefit of, and be binding
upon, the successors, assigns, heirs, executors, and administrators of the
parties hereto and shall inure to the benefit of and be enforceable by each
person who shall be a holder of Registrable Securities from time to time;
provided, however, that prior to the receipt by the Company of adequate written
notice of the transfer of any Registrable Securities specifying the full name
and address of the transferee, the Company may deem and treat the person listed
as the holder of such shares in its records as the absolute owner and holder of
such shares for all purposes, including the payment of dividends or any
redemption price.

        3.4 ENTIRE AGREEMENT. This Agreement, the Exhibits and Schedules hereto,
the Purchase Agreement and the other documents delivered pursuant thereto
constitute the full and entire understanding and agreement between the parties
with regard to the subjects hereof and no party shall be liable or bound to any
other in any manner by any representations, warranties, covenants and agreements
except as specifically set forth herein and therein.



                                      13.
<PAGE>   15

        3.5 SEVERABILITY. In the event one or more of the provisions of this
Agreement should, for any reason, be held to be invalid, illegal or
unenforceable in any respect, such invalidity, illegality, or unenforceability
shall not affect any other provisions of this Agreement, and this Agreement
shall be construed as if such invalid, illegal or unenforceable provision had
never been contained herein.

        3.6 AMENDMENT AND WAIVER.

               (a) Except as otherwise expressly provided, this Agreement may be
amended or modified only upon the written consent of the Company and the holders
of at least two-thirds (2/3) of the Registrable Securities.

               (b) Except as otherwise expressly provided, the obligations of
the Company and the rights of the Holders under this Agreement may be waived
only with the written consent of the holders of at least two-thirds (2/3) of the
Registrable Securities.

        3.7 DELAYS OR OMISSIONS. It is agreed that no delay or omission to
exercise any right, power, or remedy accruing to any Holder, upon any breach,
default or noncompliance of the Company under this Agreement shall impair any
such right, power, or remedy, nor shall it be construed to be a waiver of any
such breach, default or noncompliance, or any acquiescence therein, or of any
similar breach, default or noncompliance thereafter occurring. It is further
agreed that any waiver, permit, consent, or approval of any kind or character on
any Holder's part of any breach, default or noncompliance under the Agreement or
any waiver on such Holder's part of any provisions or conditions of this
Agreement must be in writing and shall be effective only to the extent
specifically set forth in such writing. All remedies, either under this
Agreement, by law, or otherwise afforded to Holders, shall be cumulative and not
alternative.

        3.8 NOTICES. All notices required or permitted hereunder shall be in
writing and shall be deemed effectively given: (a) upon personal delivery to the
party to be notified, (b) when sent by confirmed telex or facsimile if sent
during normal business hours of the recipient; if not, then on the next business
day, (c) five (5) days after having been sent by registered or certified mail,
return receipt requested, postage prepaid, or (d) one (1) day after deposit with
a nationally recognized overnight courier, specifying next day delivery, with
written verification of receipt. All communications shall be sent to the party
to be notified at the address as set forth on the signature pages hereof or
Exhibit A hereto or at such other address as such party may designate by ten
(10) days advance written notice to the other parties hereto.

        3.9 ATTORNEYS' FEES. In the event that any suit or action is instituted
to enforce any provision in this Agreement, the prevailing party in such dispute
shall be entitled to recover from the losing party all fees, costs and expenses
of enforcing any right of such prevailing party under or with respect to this
Agreement, including without limitation, such reasonable fees and expenses of
attorneys and accountants, which shall include, without limitation, all fees,
costs and expenses of appeals.

        3.10 TITLES AND SUBTITLES. The titles of the sections and subsections of
this Agreement are for convenience of reference only and are not to be
considered in construing this Agreement.



                                      14.
<PAGE>   16

        3.11 COUNTERPARTS. This Agreement may be executed in any number of
counterparts, each of which shall be an original, but all of which together
shall constitute one instrument.







                      [THIS SPACE INTENTIONALLY LEFT BLANK]





                                      15.
<PAGE>   17

        IN WITNESS WHEREOF, the parties hereto have executed this AMENDED AND
RESTATED REGISTRATION RIGHTS AGREEMENT as of the date set forth in the first
paragraph hereof.



COMPANY:                                 INVESTORS:

METRICOM, INC.                           VULCAN VENTURES INCORPORATED




By: /s/ TIMOTHY A. DREISBACH             By:
   ------------------------------           --------------------------------





                                         MCI WORLDCOM, INC.

                                         By:
                                            --------------------------------



                                 SIGNATURE PAGE
                         REGISTRATION RIGHTS AGREEMENT

<PAGE>   18


        IN WITNESS WHEREOF, the parties hereto have executed this AMENDED AND
RESTATED REGISTRATION RIGHTS AGREEMENT as of the date set forth in the first
paragraph hereof.



COMPANY:                                 INVESTORS:

METRICOM, INC.                           VULCAN VENTURES INCORPORATED




By:                                      By: /s/ WILLIAM D. SAVOY
   ------------------------------           --------------------------------





                                         MCI WORLDCOM, INC.

                                         By:
                                            --------------------------------



                                 SIGNATURE PAGE
                         REGISTRATION RIGHTS AGREEMENT



<PAGE>   19

        IN WITNESS WHEREOF, the parties hereto have executed this AMENDED AND
RESTATED REGISTRATION RIGHTS AGREEMENT as of the date set forth in the first
paragraph hereof.



COMPANY:                                 INVESTORS:

METRICOM, INC.                           VULCAN VENTURES INCORPORATED




By:                                      By:
   ------------------------------           --------------------------------





                                         MCI WORLDCOM, INC.

                                         By: /s/ JOHN STUPKA
                                            --------------------------------








                                 SIGNATURE PAGE
                         REGISTRATION RIGHTS AGREEMENT