<PAGE>

                                                                     EXHIBIT 4.1
================================================================================


                             Amended and Restated

                             STOCKHOLDERS AGREEMENT

                                     AMONG

                          FIBERNET TELECOM GROUP, INC.

                                      AND

                              CERTAIN STOCKHOLDERS

                         DATED AS OF JANUARY 31, 2001







================================================================================
<PAGE>

                                    AMENDED AND RESTATED STOCKHOLDERS AGREEMENT
                              ("Agreement") dated as of January 31, 2001 between
                              FIBERNET TELECOM GROUP, INC. ("Company"), SIGNAL
                              EQUITY PARTNERS, L.P. (formerly known as Signal
                              Capital Partners, L.P.), as the Majority in
                              Interest of the Purchasers ("Signal"), and NORTEL
                              NETWORKS INC. ("Nortel") (each term as defined
                              herein), amending and restating the Stockholders
                              Agreement dated as of May 7, 1999 (as amended by
                              the Amendment dated as of June 30, 2000, the
                              Amendment dated July 28, 2000, and the Amendment
                              dated August 11, 2000 the "Stockholders
                              Agreement") by and among the Company and the
                              Stockholders (as defined in the Stockholders
                              Agreement).

                 Each Stockholder owns, on the date hereof, that number of
shares of Stock (as hereinafter defined) set forth opposite such Stockholder's
name on Annex I. It is deemed to be in the best interest of the Company and the
Stockholders that provision be made for the continuity and stability of the
business and policies of the Company, and, to that end, the Company and the
Stockholders hereby set forth their agreement with respect to the shares of
Stock owned by the Stockholders.

                 NOW, THEREFORE, in consideration of the premises and of the
mutual consents and obligations hereinafter set forth, the parties hereto hereby
agree as follows:

     Section 1.  Definitions.

                 Capitalized terms used and not otherwise defined herein shall
have the meanings ascribed to them in the Securities Purchase Agreement. As used
herein, the following terms shall have the following respective meanings:

                 "Affiliate" has the meaning ascribed thereto in the Securities
Purchase Agreement.

                 "all or substantially all" shall have the meaning ascribed to
such term in the Securities Purchase Agreement.

                 "Board" means the Board of Directors of the Company.

                 "Business Day" shall mean any day other than a Saturday or
Sunday or a day on which banks are authorized or required to be closed in New
York, New York.

                 "Charter" shall mean the Certificate of Incorporation of the
Company, as amended from time to time.
<PAGE>

                 "Common Stock" shall mean the common stock, $.001 par value, of
the Company.

                 "Concordia" shall mean Concordia Telecom Management, L.L.C., a
Delaware limited liability company.

                 "Founders Shares" shall mean at any time the shares of Common
Stock, any securities which by their terms are exercisable or exchangeable for
or convertible into Common Stock, and any securities of the Company received in
respect thereof, which are held by the Founding Stockholders.

                 "Founding Stockholders" shall mean the Persons listed as
Stockholders under the heading "Founding Stockholders" in Annex I hereto, and
shall include any successor to, or assignee or transferee of, any of the
Founding Stockholders whether or not such Persons shall agree in writing to be
treated as a Founding Stockholder and to be bound by the terms and to comply
with the provisions of this Agreement.

                 "Group" shall mean:

                    (i)  in the case of any Stockholder who is an individual,
               (A) such Stockholder, (B) the spouse, lineal descendants and
               adopted children of such Stockholder and (C) any trust for the
               benefit of any of the foregoing; and


                    (ii) in the case of any Stockholder which is a corporation,
               limited liability company or partnership, (A) such corporation,
               limited liability company or partnership, (B) any corporation or
               other business organization to which such corporation, limited
               liability company or partnership shall sell or transfer all or
               substantially all of its assets or with which it shall be merged,
               (C) with respect to any limited liability company or partnership,
               any partner (general or limited) or member thereof and (D) any
               Affiliate of such corporation.

                 "Majority in Interest" has the meaning ascribed to such term in
the Securities Purchase Agreement.

                 "Nortel" shall mean Nortel Networks Inc., a Delaware
corporation.

                 "Operating Budget" has the meaning ascribed to such term in the
Securities Purchase Agreement.

                 "Person" shall mean any individual, partnership, corporation,
group, trust or other legal entity.

                 "Privately Negotiated Sale" shall mean a transaction between a
Stockholder and an unrelated party, negotiated on an arm's length basis other
than on a securities exchange, in the over the counter market or on the Nasdaq
National Market.

                 "Proportionate Percentage" shall mean:

                                                                               2
<PAGE>

                  (i)    for the purposes of Section 3, the pro rata percentage
          of Stock being offered by a Selling Group pursuant to Section 3 that
          each Stockholder (other than the Selling Group) shall be entitled to
          purchase, which pro rata percentage, as to each such Stockholder,
          shall be the percentage figure which expresses the ratio, on a Common
          Stock equivalent basis (which for purposes of this Agreement shall
          mean the conversion of all securities convertible into Common Stock
          and the exercise of all options and warrants then exercisable for
          Common Stock), between the number of shares of Stock owned by such
          Stockholder and the aggregate number of shares of Stock owned by all
          Stockholders (other than the Selling Group) at the date of
          determination;

                         (ii)   for the purposes of Section 4, the pro rata
              percentage of the number of shares of Stock to which a Section 4
              Offer relates that each Stockholder shall be entitled to Transfer
              to the Section 4 Purchaser, which pro rata percentage, as to each
              such Stockholder, shall be the percentage figure which expresses
              the ratio, on a Common Stock equivalent basis, between the number
              of shares of Stock owned by such Stockholder and the aggregate
              number of shares of Stock owned by all Stockholders and the
              Section 4 Offeree at the date of determination; and

                         (iii)  for the purposes of Section 7, the pro rata
              percentage of Stock subject to purchase pursuant to Section 7 that
              each Stockholder shall be entitled to purchase, which pro rata
              percentage, as to each such Stockholder, shall be the percentage
              figure which expresses the ratio, on a Common Stock equivalent
              basis, between the number of shares of Stock owned by such
              Stockholder and the aggregate number of shares of Stock owned by
              all Stockholders at the date of determination.

                 "Purchasers" shall mean the Persons listed as Stockholders
under the heading "Purchasers" in Annex I hereto, and shall include any
successor to, or assignee or transferee of, any of the Purchasers whether or not
such Persons shall agree in writing to be treated as a Purchaser and to be bound
by the terms and to comply with the provisions of this Agreement, each a
"Purchaser".

                 "Qualified Public Offering" shall mean (i) for purposes of the
Charter, the Proxy (as hereinafter defined), and Sections 2(a), 2(b), 4, 8 and 9
of this Agreement (together, the "Surviving Provisions"), a fully underwritten
public offering (underwritten by an underwriter of national reputation) of
shares of Common Stock registered pursuant to the Securities Act with proceeds
to the Company of at least $75,000,000 (net of underwriting discounts and
expenses) or otherwise on terms reasonably acceptable to the Majority in
Interest and Nortel, and (ii) solely for purposes of this Agreement
(specifically excluding any of the Surviving Provisions), any closing of any
offering of securities of the Company pursuant to that Amendment No. 4 to Form
S-1 on Form S-3 under the Securities Act ("S-3"), as filed with the Securities
and Exchange Commission on January 18, 2001, as such S-3 may be amended or
supplemented from time to time, with cash proceeds to the Company of at least
$10,000,000.

                                                                               3
<PAGE>

                 "Securities Act" shall mean the Securities Act of 1933 together
with any applicable regulations, as the same may be amended from time to time.

                 "Securities Purchase Agreement" shall mean the Securities
Purchase Agreement dated as of May 7, 1999 among the Company and the purchasers
named therein.

                 "Selling Group" shall mean a Stockholder or a member of the
Group of a Stockholder proposing to Transfer its Stock, or which has delivered a
notice of intention to Transfer, pursuant to Section 3 or Section 4 hereof.

                 "Series C Preferred Stock" shall mean the Series C Convertible
Preferred Stock, par value $.001, of the Company.

                 "Series D Preferred Stock" shall mean the Series D Convertible
Preferred Stock, par value $.001, of the Company.

                 "Series E Preferred Stock" shall mean the Series E Convertible
Preferred Stock, par value $.001, of the Company.

                 "Series F Preferred Stock" shall mean the Series F Convertible
Preferred Stock, par value $.001, of the Company.

                 "Series H Preferred Stock" shall mean the Series H Convertible
Preferred Stock, par value $.001, of the Company.

                 "Series I Preferred Stock" shall mean the Series I Convertible
Preferred Stock, par value $.001, of the Company.

                 "Signal" shall mean Signal Equity Partners, L.P., a Delaware
limited partnership.

                 "Stock" shall mean (i) the presently issued and outstanding
shares of Common Stock, Series C Preferred Stock, Series D Preferred Stock,
Series E Preferred Stock, Series F Preferred Stock, Series H Preferred Stock and
Series I Preferred Stock, and any options, warrants or other instruments
exercisable therefor (which options, warrants or other instruments shall be
deemed to be that number of outstanding shares of Stock for which they are
exercisable), (ii) any additional shares of capital stock of the Company
hereafter issued and outstanding and (iii) any shares of capital stock of the
Company into which such shares may be converted or for which they may be
exchanged or exercised; provided, however, that any securities issued under the
S-3 shall not be considered Stock for purposes of this Agreement.

                 "Stockholders" shall mean those Persons identified on Annex I
and shall include any other person who agrees in writing with the parties hereto
to be bound by and to comply with all applicable provisions of this Agreement as
a Stockholder hereunder.

                                                                               4
<PAGE>

                 "Transfer", as to any Stock shall mean to sell, or in any other
way transfer, assign, pledge, distribute, encumber or otherwise dispose of, such
Stock, either voluntarily or involuntarily and with or without consideration.

                 "Trident" shall mean Trident Telecom Partners LLC, a Delaware
limited liability company.

     Section 2.   Limitations on Transfers of Stock by Stockholders.

          (a)  The Stockholders shall not, at any time during the term of this
Agreement, Transfer any Stock without first complying with the provisions of
Sections 4 and 6; provided, that a Stockholder may Transfer Stock to another
member of the Group of such Stockholder without complying with Sections 4 and 6
if the recipient of such Stock shall agree in writing with the parties to this
Agreement to be bound by and to comply with all applicable provisions of this
Agreement and to be deemed a Stockholder.  Any Transfer made or attempted to be
made in contravention of the terms of this Section 2 shall be null and void;

          (b)  Notwithstanding anything to the contrary in this Agreement, each
Stockholder hereby agrees that it shall not Transfer any Stock for a period of
one (1) year after June 30, 2000 (the "Company Lock-Up"); provided, however,
that (i) if a Stockholder enters into a lock-up agreement at the request of the
managing underwriter(s) (the "Managing Underwriter") of a Qualified Public
Offering (the "Underwriter Lock-Up Agreement"), and (ii) the Company's common
stock registered pursuant to the Qualified Public Offering commences trading on
the Nasdaq National Market, the Stock subject to the Underwriter Lock-Up
Agreement shall no longer be subject to the Company Lock-Up upon the termination
or release of that Stock from the Underwriter Lock-Up Agreement pursuant to the
terms of such Underwriter Lock-Up Agreement; and provided, further, that a
Stockholder may Transfer Stock to another member of the Group of such
Stockholder if the recipient of such stock shall agree in writing with the
parties to this Agreement to be bound by and comply with all applicable
provisions of this Agreement and be deemed to be a Stockholder;

          (c)  Each Stockholder agrees to enter into an Underwriter Lock-Up
Agreement upon the request of the Company or the Managing Underwriter (for a
period of time not to exceed 180 days); provided, however, the Stockholder shall
not be obligated to enter into such agreement unless all of the executive
officers and directors of the Company and each beneficial owner of more than 5%
of the outstanding Common Stock of the Company (as determined in accordance with
Rule 13d of the Securities Exchange Act of 1934), shall have entered into
similar agreements; and

          (d) In the event that a Stockholder enters into an Underwriter Lock-Up
Agreement pursuant to Sections 2(b) or (c) above, the Company agrees that, at
the request of any such Stockholder, it will waive the Company Lock-Up for such
requesting Stockholder in connection with one sale, to be consummated prior to
September 30, 2000, of up to 30 % of such Stockholder's Stock in a Privately
Negotiated Sale; provided, however, that the Privately Negotiated Sale shall not
be effective unless (i) the Managing Underwriter shall have granted a waiver to
such Stockholder pursuant to the Underwriter Lock-Up Agreement in connection
with such sale, and (ii) the person or entity acquiring such Stock shall become
a party to the
                                                                               5
<PAGE>

Stockholders Agreement (including, without limitation, the Company Lock-Up), the
Underwriter Lock-Up Agreement and the Registration Rights Agreement and shall
have all rights, and shall observe all obligations, then applicable to the
selling Stockholder in connection therewith.


     Section 3.    [Intentionally Omitted]
     Section 4.    Tag-along Right.

          (a)  In the event that any Stockholder or group of Stockholders acting
jointly ("Section 4 Offerors") desire to Transfer shares of Stock constituting
twenty percent (20%) or more of the Company's Common Stock, as determined on a
fully diluted basis assuming the full exercise and conversion of the outstanding
securities of the Company (the "Section 4 Offer") to a Person (the "Section 4
Purchaser"), the Section 4 Offerors shall promptly forward a notice (the
"Section 4 Offer Notice") to the Stockholders.  Subject to Section 4(b), the
Section 4 Offerors shall not Transfer any Stock to the Section 4 Purchaser
unless the terms of the Section 4 Offer are extended to the Stockholders with
respect to their Proportionate Percentage of the aggregate number of shares of
Stock (on a Common Stock equivalent basis) to which the Section 4 Offer relates,
whereupon each Stockholder shall be entitled to Transfer to the Section 4
Purchaser pursuant to the Section 4 Offer the Stockholder's Proportionate
Percentage of the aggregate number of shares of Stock (on a Common Stock
equivalent basis) to which the Section 4 Offer relates by delivering a written
notice of acceptance to the Section 4 Offerors within 15 days after delivery of
the Section 4 Offer Notice.

          (b)  Anything contained herein to the contrary notwithstanding, any
purchaser of Stock pursuant to this Section 4 which is not then a Stockholder
shall agree in writing to be bound by all applicable provisions of this
Agreement and shall be deemed to be a Stockholder for all purposes of this
Agreement.

          (c)  Anything contained herein to the contrary notwithstanding, (i)
any Transfer by Nortel of any of the shares of Stock held by Nortel shall not be
subject to the provisions of this Section 4 and (ii) Nortel shall be entitled to
Transfer shares of Stock held by Nortel to a Section 4 Purchaser pursuant to a
Section 4 Offer only in the event that such Section 4 Purchaser is purchasing at
least twenty percent (20%) of the Company's Common Stock, as determined on a
fully diluted basis assuming the full exercise and conversion of the outstanding
securities of the Company.

     Section 5.   Right of First Offer.

          (a)  In the event that Signal desires to propose to the Company to
Transfer to a Person all or substantially all of the then outstanding Stock
and/or substantially all of the stock and/or equity interests of the Company,
which includes more than fifty percent (50%) of the Stock owned or held by
Signal (the "Section 5 Offer"), Signal shall deliver a written notice to Trident
and the Founding Stockholders with respect to such Section 5 Offer, which shall
be irrevocable for a period of 10 days.  Trident and the Founding Stockholders
shall have the right to offer (the "Section 5 Purchase Offer") to purchase that
number of shares of Stock owned or

                                                                               6
<PAGE>

held by Signal included in the Section 5 Offer in any written notice delivered
to Signal within said 10-day period. Signal shall have the right to condition
its acceptance of the Section 5 Purchase Offer, and Trident and the Founding
Stockholders shall consent to such conditions, on only the following: (i)
approval by Signal of the Section 5 Purchase Offer and (ii) execution of all
agreements and documents in connection with the transactions contemplated by the
Section 5 Purchase Offer within 60 Business Days after Signal's delivery of
written notice to Trident and the Founding Stockholders ("Section 5 Offer
Acceptance Notice") accepting the Section 5 Purchase Offer.

          (b)  Notwithstanding anything contained herein to the contrary, if
either Trident and/or the Founding Stockholders shall not have made a Section 5
Purchase Offer pursuant to this Section 5 and/or (x) Trident and the Founding
Stockholders or (y) Trident or the Founding Stockholders shall not have received
a Section 5 Offer Acceptance Notice pursuant to Section 5(a), the terms and
provisions of this Section 5 shall be of no further effect, and the terms and
provisions of Section 6 shall apply to any subsequent Section 5 Offer.

     Section 6.  Drag Along Right.

               Anything contained herein to the contrary notwithstanding, if at
any time after the terms and provisions of Section 5 shall not apply pursuant to
the terms of Section 5, the Board, with the consent of the director(s) to be
appointed to the Board of Directors of the Company by Signal, shall approve (i)
a bona fide arms length proposal from a Person for the Transfer, directly or
indirectly, of all or a majority of the Stock of the Company to such Person,
(ii) the merger or consolidation of the Company with or into another Person in
which the Stockholders will receive cash or securities of any other Person for
their shares or (iii) the sale by the Company of all or substantially all of its
assets to a Person, in each of the above cases for a specified price payable in
cash or otherwise and on specified terms and conditions (a "Sale Proposal"),
then the Board may deliver a notice (a "Required Sale Notice") with respect to
such Sale Proposal to each other Stockholder (as well as each other holder of
any shares of Stock) stating that Signal has approved the Sale Proposal, the
Company proposes to effect the Sale Proposal and providing the identity of the
Persons involved in such Sale Proposal and the terms thereof. Each such
Stockholder and the members of the Group thereof, upon receipt of a Required
Sale Notice, shall be obligated to sell their Stock and participate in the
transaction (a "Required Sale") contemplated by the Sale Proposal, vote their
shares of Stock in favor of such Sale Proposal at any meeting of Stockholders
called to vote on or approve such Sale Proposal and otherwise to take all
necessary action to cause the Company and the Stockholders to consummate such
Required Sale. Any such Required Sale Notice may be rescinded by the Board, with
the written consent of Signal, by delivering written notice thereof to all of
the Stockholders.

     Section 7.  Pre-emptive Rights.

     (a)  Except in the case of Excluded Securities, the Company shall not
issue, sell or exchange, agree to issue, sell or exchange, or reserve or set
aside for issuance, sale or exchange, any (i) Stock, (ii) any other equity
security of the Company, (iii) any debt security of the Company which by its
terms is convertible into or exchangeable for any equity security of the Company
or has any other equity feature, (iv) any security of the Company that is a
combination

                                                                               7
<PAGE>

of a debt and equity security or (v) any option, warrant or other right to
subscribe for, purchase or otherwise acquire any security of the Company
specified in the foregoing clauses (i) through (iv), unless in each case the
Company shall have first offered to sell such securities to the Stockholders
(the "Offered Securities"), at each Stockholder's respective Proportionate
Percentage at a price and on such other terms and conditions as shall have been
specified by the Company in writing delivered to each Stockholder (the "Offer"),
which Offer by its terms shall remain open and irrevocable for a period of 30
days from the date it is delivered by the Company to the Stockholder.

          (b)  The Company may specify in the Offer that all or a minimum amount
of the Offered Securities must be sold in such offering (to the Stockholders
and/or any third parties pursuant to Section 7(d)), in which case any Notice of
Acceptance (as defined below) shall be deemed conditioned upon (i) receipt of
Notices of Acceptance of all or such minimum amount, as applicable, of the
Offered Securities and/or (ii) the sale of all, or such minimum amount, as
applicable, of the Offered Securities pursuant to Section 7(d).

          (c)  Notice of the Stockholder's intention to accept, in whole or in
part, an Offer shall be evidenced by a writing signed by such Stockholder and
delivered to the Company prior to the end of the 30-day period of such Offer,
setting forth such portion of the Offered Securities the Stockholders elect to
purchase (the "Notice of Acceptance").

          (d)  In the event that Notice of Acceptance is not given by the
Stockholders in respect of all the Offered Securities, the Company shall have
120 days from the expiration of the foregoing 30-day period to sell all or any
part of such Offered Securities as to which Notice of Acceptances have not been
given by the Stockholders (the "Refused Securities") to any other person or
persons, but only upon terms and conditions in all material respects, including,
without limitation, unit price and interest rates, which are no more favorable
to such other person or persons and no less favorable to the Company than those
set forth in the Offer.  Upon the closing, which shall include full payment to
the Company, of the sale to such other person or persons of all the Refused
Securities, the Stockholders shall purchase from the Company, and the Company
shall sell to the Stockholders, the Offered Securities in respect of which
Notice of Acceptances were delivered to the Company by the Stockholders, at the
terms specified in the Offer.

          (e)  In each case, any Offered Securities not purchased by the
Stockholders or any other person or persons in accordance with Section 7(d) may
not be sold or otherwise disposed of until they are again offered to the
Stockholders under the procedures specified in Sections 7(a), (c) and (d).

          (f)  The rights of the Stockholders under this Section 7 shall not
apply to the following securities (the "Excluded Securities"):

                 (i)    (A) up to 10,000,000 shares (as adjusted equitably for
              stock dividends, stock splits, combinations, etc.) of Common Stock
              issuable upon exercise of stock options granted to officers,
              employees or directors of the Company or its subsidiaries pursuant
              to and in accordance with any Employee Plan duly authorized by the
              Board and/or the appropriate committee thereof, (B)

                                                                               8
<PAGE>

              shares of Common Stock issued upon conversion of shares of Series
              C Preferred Stock, Series D Preferred Stock, Series E Preferred
              Stock and Series F Preferred Stock and (C) shares of Common Stock
              issued upon exercise of the Warrants, including in the case of
              (A), (B) and (C), any additional shares of Common Stock as may be
              issued by virtue of antidilution provisions, if any, applicable to
              such options or shares, as the case may be;

                 (ii)   Stock issued as a stock dividend or upon any stock
              split or other subdivision or combination of shares of Stock;

                 (iii)  Stock issued as part of a Qualified Public Offering;

                 (iv)   Common Stock issued upon conversion of convertible
              securities outstanding on the date of this Agreement and disclosed
              on the appropriate Schedule to the Securities Purchase Agreement;

                 (v)    Common Stock or other equity securities or instruments
              exercisable for or convertible into equity securities issued as
              part of a strategic arrangement or alliance by the Company or its
              Subsidiaries to building licensors or landlords, carriers, joint
              venture partners, vendors (other than equipment vendors and
              software vendors), consultants, lessors or lenders, and securities
              or instruments issued in connection with acquisitions, as each
              such transaction is approved by the Board of the Company;
              provided, that such issuances do not, in the aggregate, involve
              the issuance of securities accounting for in excess of five
              percent (5%) of the fully diluted outstanding Common Stock of the
              Company;

                 (vi)    426,333 shares of Series H Preferred Stock issued or
              to be issued to Nortel Networks Inc. (and shares of Common Stock
              to be issued upon conversion thereof); and

                 (vii)   62,500 shares of Series I Preferred Stock issued or to
            be issued to Nortel Networks Inc. (and shares of Common Stock to be
            issued upon conversion thereof).

     Section 8.  Irrevocable Proxy.

          (a)  Each Founding Stockholder hereby grants to the Managing
Purchasers and their assignees an irrevocable proxy coupled with an interest
(the "Proxy") attached hereto as Exhibit B to vote the Founders Shares at each
and all meetings of the stockholders of the Company, to execute and otherwise to
exercise any consensual rights with respect to such Founders Shares to the same
extent and with the same effect as each of the Founding Stockholders could do
under any applicable agreement or instrument or any applicable laws or
regulations governing the rights and powers of stockholders of the Company
(collectively, the "Proxy Rights"); provided, that the exercise of any Proxy
Rights requires the consent of the majority of the Managing Purchasers unless,
in the sole judgment of the Majority in Interest that in order to protect its
investment, the Majority in Interest requires the sole right to exercise the
Proxy Rights in which case the Majority in Interest shall upon 10 days written
notice to each
                                                                               9
<PAGE>

other Managing Purchaser have the sole right to exercise the Proxy Rights until
the Majority in Interest, in its sole discretion, shall deem otherwise. Anything
contained in the preceding sentence to the contrary notwithstanding, the Proxy
shall automatically terminate without further action upon the earliest to occur
of (i) the valid and enforceable Transfer of all Stock owned by such
Stockholder, (ii) the valid and enforceable Transfer of any Stock owned by such
Stockholder in a Privately Negotiated Sale pursuant to the provisions of Section
2(d) of this Agreement (a "Permitted Privately Negotiated Sale"); provided,
that, contemporaneously with such Permitted Privately Negotiated Sale, such
Stockholder shall grant to the Managing Purchasers and their assignees the Proxy
attached hereto as Exhibit B with respect to the Proxy Rights of any and all
Founders Shares not Transferred by such Stockholder in such Permitted Privately
Negotiated Sale, (ii) a Qualified Public Offering or (iii) three years from the
date hereof. The Managing Purchasers shall have the right to assign the Proxy to
any of their Affiliates.

          (b)  If the Proxy granted pursuant to Section 8(a) is not valid or is
otherwise ineffective for any reason, then each Founding Stockholder shall vote
all of his respective Founders Shares in the same manner as the Majority in
Interest votes any shares of Stock owned by the Majority in Interest at any and
all meetings of the stockholders of the Company, by written consent in lieu
thereof and otherwise in connection with any exercise of any consensual rights
with respect to such Founders Shares.

     Section 9.  Voting Agreement.

          (a)  Each Stockholder shall vote all of his or its Shares (by Proxy if
applicable) and shall take all other necessary or desirable actions within his
or its control (whether in such Stockholder's capacity as a stockholder of the
Company or otherwise, and including, without limitation, attendance at meetings
in person or by proxy for purposes of obtaining a quorum and execution of
written consents in lieu of meetings), and the Company shall take all necessary
and desirable actions within its control (including, without limitation, calling
special Board and stockholder meetings), so that:

                 (i)     the authorized number of directors on the Board of the
              Company shall be established at no less than six (6) directors;
              and

                 (ii)    one Person designated by the Majority in Interest and
              one Person designated by Trident shall have the right to observe
              and attend all meetings, whether held by teleconference or
              otherwise, of the Board of the Company and to receive all
              information and notices received by directors on the Board of the
              Company.

       (b)     The consent of the director(s) designated by each of Signal and
Trident to the Board will be necessary for (i) any material change or
modification of the Company's business plan as agreed upon by the Managing
Purchasers as of the date hereof (the "Business Plan"), (ii) the redemption of
any capital stock, (iii) the issuance of securities senior to or on a parity
with the Preferred Stock, (iv) the authorization or issuance of securities
convertible into such senior or parity securities or (v) the amendment of the
Certificate of Incorporation of the Company.  The consent of the director(s)
designated by Signal to the Board will be necessary for (i) any

                                                                              10
<PAGE>

transactions with an Affiliate or related party to the Company, (ii) any merger
or consolidation of the Company or any Subsidiary of the Company with any other
entity, (iii) the sale of all or substantially all of the assets of the Company
or its Subsidiaries, (iv) the approval or authorization of any liquidation, (v)
the removal of any senior executive of the Company, (vi) the incurrence of any
fund Indebtedness in excess of $500,000, (vii) the incurrence of any capital
expenditures in any 12-month period in excess of $100,000, which such capital
expenditures were not authorized in or by the Company's Business Plan or
Operating Budget or (viii) any changes to or removal of the Company's auditor.

     Section 10.  Covenants.

               The Company and the Stockholders shall take any and all necessary
actions to make Exchange Act Filings (as defined in the Securities Purchase
Agreement) immediately after the Closing.

     Section 11.  Legend on Stock Certificates.

               Each certificate representing shares of Stock shall bear a legend
containing the following words (in addition to any other legend required by law
or applicable agreement):

          "THE SALE, TRANSFER, ASSIGNMENT, PLEDGE OR ENCUMBRANCE OF THE
          SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO THE TERMS
          AND CONDITIONS OF AN AMENDED AND RESTATED STOCKHOLDERS AGREEMENT DATED
          AS OF JANUARY 31,  2001, BY AND AMONG FIBERNET TELECOM GROUP, INC. AND
          CERTAIN HOLDERS OF THE OUTSTANDING CAPITAL STOCK OF SUCH CORPORATION
          (AS SUCH MAY BE AMENDED OR AMENDED AND RESTATED).  COPIES OF SUCH
          AGREEMENT MAY BE OBTAINED AT NO COST BY WRITTEN REQUEST MADE BY THE
          HOLDER OF RECORD OF THIS CERTIFICATE TO THE SECRETARY OF SUCH
          CORPORATION."

     Section 12.  Additional Shares of Stock; Etc.

               In the event additional shares of Stock are issued by the Company
to a Stockholder of the Company at any time during the term of this Agreement,
either directly or upon the exercise or exchange of securities of the Company
exercisable for or exchangeable into shares of Stock, the Company shall cause
such additional shares of Stock, as a condition to such issuance, to become
subject to the terms and provisions of this Agreement.

     Section 13.  Duration of Agreement; Compliance.

               The rights and obligations of each Stockholder under this
Agreement shall terminate upon the valid and enforceable Transfer of all Stock
owned by such Stockholder. Notwithstanding anything contained herein to the
contrary, the only sections of this Agreement that shall survive a Qualified
Public Offering (as such is term defined in clause (ii) of the definition in
Section 1 hereof) are Sections 1, 2(a), 2(b), 2(c), 4, 8, 9, 11, 12, 13, 14, 15,
16, 17,

                                                                              11
<PAGE>

18, 19, 20 and 21.  Moreover, notwithstanding anything to the contrary contained
herein, the only sections of this Agreement that shall survive a Qualified
Public Offering (as such term is defined in clause (i) of the definition in
Section 1 hereof) are Sections 2(b), 11, 13, 14, 15, 16, 18, 19, 20 and 21,
which sections shall survive for a period of nine (9) months following such
Qualified Public Offering, at which time this Agreement shall terminate.

     Section 14.  Severability; Governing Law.

               If any provision of this Agreement shall be determined to be
illegal and unenforceable by any court of law, the remaining provisions shall be
severable and enforceable in accordance with their terms. This Agreement shall
be governed by and construed and enforced in accordance with the laws of the
State of New York (without regard to principles of conflicts of laws), except to
the extent that this Agreement relates to the internal laws of the Company,
which shall be governed by and construed and enforced in accordance with the
laws of the State of New York.

     Section 15.  Successors and Assigns.

               This Agreement shall bind and inure to the benefit of the parties
and their respective successors and assigns, transferees, legal representatives
and heirs.

     Section 16.  Notices.

               All notices, requests, consents and other communications
hereunder to any party shall be deemed to be sufficient if contained in a
written instrument delivered in person or by telecopy or sent by nationally-
recognized overnight courier or first class registered or certified mail, return
receipt requested, postage prepaid, addressed to such party at the address set
forth below or at such other address as may hereafter be designated in writing
by such party to the other parties:

          if to the Company, to:


          FiberNet Telecom Group, Inc.
          570 Lexington Avenue
          New York, NY  10022
          Telephone:  (212) 405-6200
          Telecopy:    (212) 421-8860
          Attention:    President

          with a copy to:

          Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
          666 Third Avenue
          New York, NY 10017
          Telephone:  (212) 935-3000
          Telecopy:    (212) 983-3115
          Attention:    Gordon Caplan, Esq.

          if to Nortel, to:

                                                                              12
<PAGE>

          Nortel Networks, Inc.
          GMS 991 15 A40
          2221 Lakeside Boulevard
          Richardson, TX  75082-4399
          Attention:  Paul D. Day, Vice President
          Customer Finance North America
          Facsimile:  (972) 684-3679

          with a copy to:

          Jenkens & Gilchrist, a Professional Corporation
          1445 Ross Avenue
          Suite 3200
          Dallas, Texas  75202
          Attention:  Michael J. Pendleton, Esq.
          Telephone:  (214) 855-4161
          Telecopy:  (214) 855-4300

          if to the Stockholders, to their respective addresses set forth on
Annex I hereto

               All such notices, requests, consents and other communications
shall be deemed to have been delivered (a) in the case of personal delivery or
delivery by telecopy, on the date of such delivery, (b) in the case of dispatch
by nationally-recognized overnight courier, on the next business day following
such dispatch and (c) in the case of mailing, on the third business day after
the posting thereof.

     Section 17.  Modification.

               Except as otherwise provided herein, neither this Agreement nor
any provisions hereof can be modified, changed, discharged or terminated except
by an instrument in writing signed by the Company and a Majority in Interest of
the Purchasers; provided, however, that any modification or amendment which
relates to the rights and obligations of Nortel under this Stockholders
Agreement shall also require Nortel to execute such instrument in writing;
provided, further, that no modification or amendment shall discriminate against
any Stockholder without the consent of such Stockholder; provided, further, that
any modification or amendment to Section 2(b) of this Agreement or this proviso,
shall require the (i) Company, (ii) Nortel (or its successor) and (iii) at least
two of Concordia (or its successor), Signal (or its successor) or Trident (or
its successor), to execute such instrument in writing.

     Section 18. Headings.

               The headings of the sections of this Agreement have been inserted
for convenience of reference only and shall not be deemed to be a part of this
Agreement.

                                                                              13
<PAGE>

     Section 19.  Nouns and Pronouns.

               Whenever the context may require, any pronouns used herein shall
include the corresponding masculine, feminine or neuter forms, and the singular
form of names and pronouns shall include the plural and vice versa.

     Section 20.  Entire Agreement.

               This Agreement and the other writings referred to herein or
delivered pursuant hereto contain the entire agreement among the parties hereto
with respect to the subject matter hereof and supersede all prior and
contemporaneous agreements and understandings with respect thereto. The parties
hereto acknowledge that Sections 3, 5, 6, 8, 9 and 10 of this Agreement shall
not apply to Nortel and Nortel shall have no rights or obligations under these
sections.

     Section 21.  Counterparts.

               This Agreement may be executed in any number of counterparts, and
each such counterpart hereof shall be deemed to be an original instrument, but
all such counterparts together shall constitute but one agreement.

                                                                              14
<PAGE>

            IN WITNESS WHEREOF, the parties hereto have executed this
Stockholders Agreement on the date first above written.

                              FIBERNET TELECOM GROUP, INC.



                              By: /s/    Michael S. Liss
                                  ----------------------------------------
                                  Name:  Michael S. Liss
                                  Title: President

                              SIGNAL EQUITY PARTNERS, L.P.

                              By: Signal Equity Advisors, L.P.
                              Its: General Partner

                              By: Signal Equity Advisors, Inc.
                              Its: General Partner

                              By: /s/   Timothy P. Bradley
                                  ----------------------------------------
                                  Name: Timothy P. Bradley
                                  Title: President



                              NORTEL NETWORKS INC.


                              By: /s/ Robert D. Beiter
                                  ----------------------------------------
                                  Name: Robert D. Beiter
                                  Title: Director, Customer Finance

For Purpose of Section 17 only:

TRIDENT TELECOM PARTNERS, LLC

By:  Trident Telecom Management LLC
Its:  Managing Member

By:  Needham Capital Management, Inc.
Its:  Managing Member


By: /s/    Ronald W. Kuzon
    ----------------------------------
    Name:  Ronald W. Kuzon
    Title: President

<PAGE>

                                    ANNEX I
                                    -------

                          FIBERNET TELECOM GROUP, INC.
                                Stockholder List
                                ----------------


              Founding Stockholders                       Shares
              ---------------------                       ------

Frank Chiaino                                                   259,162
6700 Song Hill Lane
Rochester, NY 14564
(716) 924-5481 (H)
-----------------------------------------------------------------------
LPS Consultants, Inc.                                           763,890
c/o Petrocelli Communications Company
22-09 Queens Plaza North
Long Island City, NY 11101
(718) 752-2200 (O)
-----------------------------------------------------------------------
LTJ Group, Inc.                                               4,381,690
c/o New Horizons
2821 Cattleman Road
Sarasota, FL 34232
Attn: Joseph Tortoretti
(941) 308-2002 (O)
-----------------------------------------------------------------------
SMFS, Inc.                                                    6,700,000
c/o Petrocelli Communications Company
22-09 Queens Plaza North
Long Island City, NY 11101
(718) 752-2200 (O)
-----------------------------------------------------------------------
                                      Total:                 12,104,742
-----------------------------------------------------------------------

              Institutional Purchasers                    Shares
              ------------------------                    ------

Adirondack Capital Partners Inc.                                 25,855
711 Fifth Avenue, 14th Floor
New York, NY 10022
-----------------------------------------------------------------------
Alexander Enterprise Holdings Corp.                           1,077,611
c/o Island Capital Management
950 Third Avenue, 16th Floor
New York, NY 10022
Attn: Richard O'Connell
(212) 688-4811 (O)
-----------------------------------------------------------------------
<PAGE>

-----------------------------------------------------------------------
Allspace International Corp                                      49,288
201 Main Street
Allenhurst, NJ 07711
Attn: David Epstein
(732) 774-1500 (O)
(732) 660-0041 (F)
-----------------------------------------------------------------------
Anniston Capital, Inc.                                           35,379
445 Park Avenue, 6th Floor
New York, NY 10022
Attn: Michael A. Asch
(212) 750-2545 (O)
-----------------------------------------------------------------------
Birdie Capital Corp.                                            143,526
1315 Club Drive
Hewlett, NY 11557
Attn: Ira Rosenbloom
(212) 482-3740
-----------------------------------------------------------------------
Burden Direct Investment Fund III                             1,565,286
10 East 53rd Street, 32nd Floor
New York, NY 10022
Attn: Jeffrey Weber
(212) 872-1133 (O)
(212) 872-1199 (F)
-----------------------------------------------------------------------
Concordia Telecom Management, L.L.C.                          1,485,754
c/o FiberNet Telecom Group, Inc.
570 Lexington Avenue, 3rd Floor
New York, NY 10022
Attn: Michael S. Liss
(212) 405-6201 (O)
(212) 421-8920 (F)
-----------------------------------------------------------------------
Cycad Limited                                                    92,986
c/o Ron Kuzon
445 Park Avenue, 6th Floor
New York, NY 10022
-----------------------------------------------------------------------
Cytra Corporation                                                58,864
-----------------------------------------------------------------------
D&DF WaterView Partners, L.P.                                     1,469
Carnegie Hall Tower
152 West 57th Street, 46th Floor
New York, NY 10019
Attn: William Vrattos
(212) 277-5614 (O)
(212) 974-1753 (F)
-----------------------------------------------------------------------
<PAGE>

-----------------------------------------------------------------------
Delta Opportunity Fund (Institutional), LLC                     147,170
c/o Diaz & Altschul Advisors, LLC
950 Third Avenue, 16th Floor
New York, NY  10022
Attn: Arthur G. Altschul, Jr.
(212) 751-1011 (O)
(212) 751-5757 (F)
-----------------------------------------------------------------------
Delta Opportunity Fund, Ltd.                                    220,750
c/o Diaz & Altschul Advisors, LLC
950 Third Avenue, 16th Floor
New York, NY  10022
Attn: Arthur G. Altschul, Jr.
(212) 751-1011 (O)
(212) 751-5757 (F)
with copies to:
c/o International Fund Administration, Ltd.
48 Par La Ville Road, Suite 464
Hamilton HM 11, Bermuda, B.W.I.
(441) 295-4718 (O)
(441) 295-9637 (F)
-----------------------------------------------------------------------
Emral Holdings Limited                                          108,041
C/o The Zanett Group
135 East 57th Street, 15th Floor
New York, NY 10022
Attn: Mr. Guazzoni
(212) 753-4809 (O)
-----------------------------------------------------------------------
Exeter Capital Partners IV, L.P.                                551,900
c/o The Exeter Group
10 East 53rd Street
New York, NY 10022
Attn: Kurt Bergquist
(212) 872-1172 (O)
-----------------------------------------------------------------------
Exeter Equity Partners, L.P.                                    183,970
c/o The Exeter Group
10 East 53rd Street
New York, NY 10022
Attn: Kurt Bergquist
(212) 872-1172 (O)
-----------------------------------------------------------------------
Fiber Island, LLC                                               183,970
c/o Island Capital Management
950 Third Avenue, 16th Floor
New York, NY 10022
Attn: Richard O'Connell
(212) 688-4811 (O)
-----------------------------------------------------------------------
<PAGE>

-----------------------------------------------------------------------
Hamaayan Institute                                               23,317
15 Dunhill Lane
Monsey, NY 10952
(914) 425-4671 (F)
-----------------------------------------------------------------------
Hi-Tel Group, Inc.                                              128,321
2400 East Commercial Blvd. #205
Ft. Lauderdale, FL 33308
Attn: Steve Hirch
(954) 202-0066
-----------------------------------------------------------------------
Interim Advantage Fund, LLC                                     140,117
Address Unknown
-----------------------------------------------------------------------
King Street Capital LP                                          288,429
575 Lexington Avenue
New York, NY 10022
Attn: Ara Cohen
(212) 350-4434 (O)
(212) 350-4702 (F)
-----------------------------------------------------------------------
King Street Capital Ltd.                                        266,239
575 Lexington Avenue
New York, NY 10022
Attn: Ara Cohen
(212) 350-4434 (O)
(212) 350-4702 (F)
-----------------------------------------------------------------------
Lancer Offshore, Inc.                                           868,884
c/o 375 Park Avenue, Suite 2006
New York, NY 10152
Attn: David Newman
(212) 521-8407 (O)
-----------------------------------------------------------------------
Lancer Partners, L.P.                                           245,438
c/o 375 Park Avenue, Suite 2006
New York, NY 10152
Attn: David Newman
(212) 521-8407 (O)
with copies to:
c/o 475 Steamboat Road
Greenwich, CT 06830
-----------------------------------------------------------------------
Madison Investment Partners II, L.P.                            183,970
660 Madison Avenue, 15th Floor
New York, NY  10021
Attn: Martha Cassidy
(212) 223-2600 (O)
(212) 223-8208 (F)
-----------------------------------------------------------------------
<PAGE>

-----------------------------------------------------------------------
Nortel Networks Inc.                                          4,888,330
2221 Lakeside Blvd.
Mailstop 991-15-A40
Richardson, TX 75082
Attn: Robert Beiter
(972) 685-1525 (O)
(972) 684-3679 (F)
-----------------------------------------------------------------------
The Orbiter Fund, Ltd.                                           40,684
c/o Lancer Partners L.P.
375 Park Avenue, Suite 2006
New York, NY 10152
Attn: David Newman
(212) 521-8407 (O)
-----------------------------------------------------------------------
Overbrook Fund I, LLC                                            91,980
c/o Overbrook Management Corporation
521 Fifth Avenue, 15th Floor
New York, NY 10175
Attn: Nora E. Jobson
(212) 661-8710 (O)
-----------------------------------------------------------------------
Pacific Alliance Limited, L.L.C.                                144,054
1010 Fifth Avenue, Suite 11A
New York, NY 10028
Attn: James Haft
(212) 759-2888 (O)
-----------------------------------------------------------------------
Penny Lane Partners, L.P.                                       923,972
767 Fifth Avenue
New York, NY 10153
Attn: William R. Denslow Jr.
(212) 980-4292 (O)
(212) 319-6046 (F)
-----------------------------------------------------------------------
Pequot Scout Fund, LP                                         1,109,356
500 Nyala Farm Road
Westport, CT 06880
Attn: Mark Broach
(203) 429-2203 (O)
(203) 429-2410 (F)
-----------------------------------------------------------------------
Petrocelli Industries, Inc.                                     338,796
c/o Petrocelli Communications Company
22-09 Queens Plaza North
Long Island City, NY 11101
(718) 752-2200 (O)
-----------------------------------------------------------------------
<PAGE>

-----------------------------------------------------------------------
Portugal Investment Group, Inc.                                 185,974
1070 Forest Avenue
Lakewood, NJ 08701
Attn: Rocky Stefansky
(732) 919-7700
-----------------------------------------------------------------------
Prism Partners I, L.P.                                          272,210
c/o Weintraub Capital Management
909 Montgomery Street, Suite 400
San Francisco, CA 94133
Attn: Nancy DeSchane
(415) 705-8787 (O)
(415) 705-8736 (F)
-----------------------------------------------------------------------
The Raptor Global Portfolio Ltd.                                551,900
40 Rowes Wharf, 2nd Floor
Boston, MA  02110
Attn: Rick Ganong
(617) 772-4645 (O)
(617) 737-0993 (F)
-----------------------------------------------------------------------
Signal Equity Management Corp.                                   33,333
10 East 53rd Street, 32nd Floor
New York, NY 10022
Attn: Timothy Bradley
(212) 872-1182 (O)
(212) 253-4235 (F)
-----------------------------------------------------------------------
Signal Equity Partners, L.P.                                  6,027,726
10 East 53rd Street, 32nd Floor
New York, NY 10022
Attn: Timothy Bradley
(212) 872-1182 (O)
(212) 253-4235 (F)
-----------------------------------------------------------------------
Taurus Telecommunications, Inc.                                 119,736
3625 Ridge Run
Canandaigua, NY 14424
Attn: Richard Sayers
(716) 396-0130 (H)
(716) 396-9237 (F)
-----------------------------------------------------------------------
Tishman Speyer FiberNet Investment Assoc.                     1,000,000
c/o Tishman Speyer Properties, L.P.
520 Madison Avenue
New York, NY 10022
Attn: Andrew Nathan
(212) 715-0375 (O)
(212) 588-1895 (F)
-----------------------------------------------------------------------
<PAGE>

-----------------------------------------------------------------------
Tishman Speyer Properties, et al.                             1,579,835
c/o Tishman Speyer Properties, L.P.
520 Madison Avenue
New York, NY 10022
Attn: Andrew Nathan
(212) 715-0375 (O)
(212) 588-1895 (F)
-----------------------------------------------------------------------
Trident Telecom Partners LLC                                  1,068,557
445 Park Avenue, 6th Floor
New York, NY 10022
Attn: Gerald Goldberg
(212) 753-4718 (O)
(212) 753-5989 (F)
-----------------------------------------------------------------------
The Viator Fund, Ltd.                                           437,925
c/o 375 Park Avenue, Suite 2006
New York, NY 10152
Attn: David Newman
(212) 521-8407 (O)
-----------------------------------------------------------------------
WaterView Partners, LP                                          391,527
Carnegie Hall Tower
152 West 57th Street, 46th Floor
New York, NY 10019
Attn: William Vrattos
(212) 277-5614 (O)
(212) 974-1753 (F)
-----------------------------------------------------------------------
West Plus One, LLC                                              201,703
c/o Griggs Resource Group
760 Old Jonas Hill Road
Lafayette, CA 94549
Attn: Brian Griggs, Manager
(925) 299-4870 (O)
(925) 299-4872 (F)
-----------------------------------------------------------------------
Winall Industries                                                23,248
c/o Needham Capital
445 Park Avenue, 6th Floor
New York, NY 10022
Attn: Gerald Goldberg
(212) 753-4718 (O)
(212) 753-5989 (F)
-----------------------------------------------------------------------
                                      Total:                 27,507,380
-----------------------------------------------------------------------

              Individual Purchasers                           Shares
              ---------------------                           ------
-----------------------------------------------------------------------
<PAGE>

-----------------------------------------------------------------------
Stephen Aiello                                                   55,180
c/o 033 Asset Management
555 California Street, 51st Floor
San Francisco, CA 94109
(415) 315-2720
-----------------------------------------------------------------------
Alena Andersen                                                    3,254
2437 Bedford Street, #E-2
Stamford, CT 06905
(203) 357-0034 (H)
-----------------------------------------------------------------------
Arthur Asch                                                     477,061
c/o Anniston Capital, Inc.
445 Park Avenue, 6th Floor
New York, NY 10022
(212) 750-2545 (O)
-----------------------------------------------------------------------
Michael A. Asch                                                 451,390
c/o Anniston Capital, Inc.
445 Park Avenue, 6th Floor
New York, NY 10022
(212) 750-2545 (O)
-----------------------------------------------------------------------
Michael Balog                                                    36,800
c/o Bank of America Securities
600 Montgomery Street, 6th Floor
San Francisco, CA 94111
(415) 627-2304 (O)
(415) 835-2964 (F)
-----------------------------------------------------------------------
Steven C. Berger                                                 23,317
44 Heather Hill Lane
Woodcliff Lake, NJ 07677
(201) 307-1230 (H)
-----------------------------------------------------------------------
Shelley Bergman                                                  23,248
9 Pheasants Run
Harrison, NY 10528
(Telephone number unpublished)
-----------------------------------------------------------------------
Howard M. Bergtraum                                               3,670
O'Sullivan Graev & Karabell, LLP
30 Rockefeller Plaza, 41st Floor
New York, NY  10112
(212) 408-2400 (O)
(212) 408-2420 (F)
-----------------------------------------------------------------------
Lawrence S. Black                                                48,603
One S.W. Columbia St., #1200
Portland, OR 97258
(800) 325-0599
-----------------------------------------------------------------------
<PAGE>

-----------------------------------------------------------------------
Robert I. Bodian                                                  3,379
c/o Mintz, Levin
666 Third Avenue, 25th Floor
New York, NY 10022
(212) 692-6726 (O)
(212) 983-3115 (F)
-----------------------------------------------------------------------
Jacques Brand                                                    33,994
10 Beechwood Lane
Scarsdale, NY  10583
(914) 722-4058 (H)
-----------------------------------------------------------------------
Gordon R. Caplan                                                  8,448
c/o Mintz, Levin
666 Third Avenue, 25th Floor
New York, NY 10022
(212) 692-6702 (O)
(212) 983-3115 (F)
-----------------------------------------------------------------------
Eve Chrust                                                        4,649
107 Saddle Rock Road
Stamford, CT 06902
-----------------------------------------------------------------------
Liza Chrust                                                       4,649
107 Saddle Rock Road
Stamford, CT 06902
-----------------------------------------------------------------------
Steven G. Chrust                                                184,390
107 Saddle Rock Road
Stamford, CT 06902
-----------------------------------------------------------------------
Michael Collado                                                  57,606
-----------------------------------------------------------------------
Kathleen Demonchy                                                11,624
400 East 57th Street, #11K
New York, NY 10022
(212) 807-8333
-----------------------------------------------------------------------
Reinaldo M. Diaz                                                  9,190
161 East 79th Street, #2B
New York, NY 10021
(212) 570-2406 (H)
(212) 570-0841 (F)
-----------------------------------------------------------------------
A. David and Francine Epstein                                    69,741
567 North Edgemere Drive
Allenhurst, NJ 07711
(732) 531-4417 (H)
(732) 660-0041 (F)
-----------------------------------------------------------------------
Leo George                                                       23,248
1615 L Street, N.W., Suite 1260
Washington, DC 20036
(202) 833-5678 (H)
-----------------------------------------------------------------------
<PAGE>

-----------------------------------------------------------------------
Lawrence Goldberg                                                77,582
c/o Credit Suisse First Boston
11 Madison Avenue
New York, NY 10010
(212) 325-3046
-----------------------------------------------------------------------
Bruno Guazzoni                                                   84,254
c/o The Zanett Group
135 East 57th Street, 15th Floor
New York, NY 10022
(212) 753-4809 (O)
with copies to:
c/o Peretz Bronstein, Esq.
60 East 42nd Street, Suite 4100
New York, NY 10165
(212) 697-6484
-----------------------------------------------------------------------
Mark S. Hauser                                                  116,234
83 Garden Road
Scarsdale, NY 10583
-----------------------------------------------------------------------
Dominick D. Keefe                                                18,213
c/o William J. Keefe
387 Grand Street, #K1001
New York, NY 10002
(212) 705-4525 (O)
-----------------------------------------------------------------------
William J. Keefe                                                 18,213
387 Grand Street, #K1001
New York, NY 10002
(212) 705-4525 (O)
-----------------------------------------------------------------------
William P. Keefe                                                 36,427
c/o William J. Keefe
387 Grand Street, #K1001
New York, NY 10002
(212) 705-4525 (O)
-----------------------------------------------------------------------
Ellen Koh                                                         4,184
201 West 77th Street, #16G
New York, NY 10022
(212) 362-2226
-----------------------------------------------------------------------
Donald A. and Darlene F. Krenz                                    9,056
-----------------------------------------------------------------------
Michael Lauer                                                   115,054
c/o 375 Park Avenue, Suite 2006
New York, NY 10152
Attn: David Newman
(212) 521-8407 (O)
-----------------------------------------------------------------------
<PAGE>

-----------------------------------------------------------------------
David C. Lee                                                     26,222
c/o Sandler Capital Management
767 Fifth Avenue, 45th Floor
New York, NY 10153
(212) 754-8100 (O)
-----------------------------------------------------------------------
Resources Trust FBO Ruth Levenstone                               6,288
-----------------------------------------------------------------------
Marshall P. Levine                                              334,220
c/o Signal Equity Partners
10 East 53rd Street, 32nd Floor
New York, NY 10022
(212) 872-1182 (O)
-----------------------------------------------------------------------
Douglas D. Lloyd                                                 34,211
-----------------------------------------------------------------------
Michael J. Marocco                                               26,222
c/o Sandler Capital Management
767 Fifth Avenue, 45th Floor
New York, NY 10153
-----------------------------------------------------------------------
John B. Marsala                                                  48,353
215 East 68th Street, Apt #27G
New York, NY 10021
Address from Joinder:
2630 NE 23rd Street
Pompano Beach, FL 33062
-----------------------------------------------------------------------
Theo W. Mueller                                                  31,193
-----------------------------------------------------------------------
Peter F. Parrinello                                              11,068
-----------------------------------------------------------------------
Dean P. Phypers                                                  23,394
-----------------------------------------------------------------------
David Post                                                       11,624
400 East 57th Street, #16K
New York, NY 10022
(Telephone number unpublished)
-----------------------------------------------------------------------
Rudolph E. Rupert                                                26,222
2 Oneida Road
Scarsdale, NY 10583
-----------------------------------------------------------------------
Stephen A. Saldanha                                             302,382
7202 Ayrshire Lane
Boca Raton, FL 33496
(561) 852-1160 (H)
-----------------------------------------------------------------------
Richard E. Sayers                                               414,481
3625 Ridge Run
Canandaigua, NY 14424
(716) 396-0130 (H)
(716) 396-9237 (F)
-----------------------------------------------------------------------
Stephen T. Shapiro                                               78,666
885 Park Avenue, #5B
New York, NY 10021
(212) 570-0493 (H)
-----------------------------------------------------------------------
<PAGE>

-----------------------------------------------------------------------
Pierre Simard                                                    26,222
26 Spruce Street
Riverside, CT 06878
(212) 632-6927
-----------------------------------------------------------------------
Eric Singer                                                      45,893
72 Hicks Street
Brooklyn, NY 11201
(718) 522-6893 (H)
(212) 856-5710
-----------------------------------------------------------------------
David H. Smith                                                  120,244
-----------------------------------------------------------------------
Lawrence B. Sorrell                                              26,222
12 Reimer Road
Scarsdale, NY 10583
(914) 472-6536 (H)
-----------------------------------------------------------------------
Simon Strauss                                                    71,493
c/o Jeffries & Co.
520 Madison Avenue
New York, NY 10022
(212) 284-2450 (O)
(212) 338-8991 (F)
-----------------------------------------------------------------------
Steven H. Tishman                                               104,888
1160 Park Avenue, #2D
New York, NY 10128
(212) 610-6138
-----------------------------------------------------------------------
Susan Weening                                                     1,860
50 Range Road
Winston, CT 06897
-----------------------------------------------------------------------
Tyler T. Zachem                                                  26,222
c/o Deutsche Bank Capital Partners
130 Liberty Street, 25th Floor
New York, NY 10006
(212) 250-8199
-----------------------------------------------------------------------
Joel W. Zimmerman                                               262,986
3555 Bison Drive
Boulder, CO 80302
(303) 444-7776
-----------------------------------------------------------------------
                                      Total:                  4,073,234
-----------------------------------------------------------------------
                                GRAND TOTAL:                 43,486,375
-----------------------------------------------------------------------
<PAGE>

                                                                       EXHIBIT A



                                    Joinder
                                    -------


          By execution of this Purchaser Joinder, the undersigned agrees to
become a party to that certain Amended and Restated Stockholders Agreement dated
as of January 31, 2001 attached hereto, among FiberNet Telecom Group, Inc., a
Delaware corporation, and certain of its stockholders.  The undersigned shall
have all the rights, and shall observe all of the obligations, applicable to a
Stockholder.

Name:
      ----------------------------------
Address for Notices:                           With copies to:

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

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

      ----------------------------------       ------------------------------
                                               Signature:
                                                          -------------------
                                               Date:
                                                     ------------------------

                                      A-1
<PAGE>

                                                                       EXHIBIT B



                               IRREVOCABLE PROXY

                          FIBERNET TELECOM GROUP, INC.

          The undersigned, _________________, hereby irrevocably and
unconditionally appoints the Managing Purchasers (as such term is defined in the
Securities Purchase Agreement) the attorney and proxy of the undersigned, with
full power of substitution, to vote, with respect to (i) the election of
directors and any and all matters presented at any and all meetings of the
stockholders of the Company and (ii) the Transfer of Stock (as such terms are
defined in the Stockholders Agreement hereinafter referred to) in such manner as
such attorneys and proxy shall, in their sole discretion, deem proper, all of
the shares of Stock of FiberNet Telecom Group, Inc., a Nevada corporation (the
"Company"), standing in the name of the undersigned (including shares of Stock
acquired after the date hereof in respect of shares of Stock held on the date
hereof) at such time (the "Proxy Shares"), including the giving of any and all
stockholder consents (such rights, collectively with the rights listed in
clauses (i) and (ii) herein, the "Proxy Rights"); provided, that the exercise of
any Proxy Rights requires the consent of the majority of the Managing Purchasers
unless, in the sole judgment of the Majority in Interest that in order to
protect its investment, the Majority in Interest requires sole right to exercise
the Proxy Rights, in which case the Majority in Interest shall upon 10 days
written notice to each other Managing Purchaser have sole control of the Proxy
Rights until the Majority in Interest, in its sole discretion, shall deem
otherwise.  This is an irrevocable proxy coupled with an interest and shall
become and remain valid and irrevocable until the automatic termination hereof
pursuant to the provisions of an Amended and Restated Stockholders Agreement,
dated as of January 31, 2001 among the undersigned, the Company and certain
stockholders of the Company, as the same may be amended from time to time.  The
granting of this proxy shall revoke all prior proxies given by the undersigned
at any time with respect to all Stock (and Proxy Shares) owned or controlled by
the undersigned and no subsequent proxies will be given with respect thereto by
the undersigned, except pursuant to the provisions of such Stockholders
Agreement.

Dated: __________ __, 2001.

                              By:__________________________________






                                      B-1