Document:

<PAGE>

                                                                 EXHIBIT 4.25

                  AMENDED AND RESTATED CO-DEVELOPMENT AGREEMENT

THIS AMENDED AND RESTATED CO-DEVELOPMENT AGREEMENT Dated For Reference the 29th
day of September, 2000

BETWEEN:

                  360NETWORKS INC.

                  ("360")

AND:

                  360FIBER LTD.

                  ("360fiber")

AND:

                  360CAYER LTEE.

                  ("360Cayer")

AND:

                  WFI URBANLINK LTD.

                  ("Urbanlink")

WHEREAS:

A. 360fiber and 360Cayer (collectively "Fiber/Cayer"), 360 and Urbanlink have
entered into a Co-Development Agreement (the "Co-Development Agreement") to
record their respective rights and obligations relating to the co-development of
telecommunications facilities in Canada.

B. 360, Fiber/Cayer and Urbanlink wish to amend and restate the Co-Development
Agreement in its entirety by executing this Agreement.

IN CONSIDERATION of the mutual agreements in this Agreement and subject to the
terms and conditions specified in this Agreement, the parties agree as follows:

<PAGE>

                                   ARTICLE 1
                                   DEFINITIONS

1.1      DEFINITIONS

In this Agreement, including the recitals and the schedules, the following words
and expressions have the following meanings unless the context otherwise
requires:

"Affiliate" of any Person means any other Person that, directly or indirectly,
controls or is controlled by or is under common control with such Person, and
for the purposes of this definition "control" (including correlative meanings of
the terms "controlled by" and "under common control with") means the power to
direct or cause the direction of the management and policies of any Person,
whether through the ownership of shares or by contract or otherwise.

"Business Day" means a day on which Canadian chartered banks are open for the
transaction of business in Vancouver, British Columbia.

"Cable" means the fiber optic cable and the strands contained therein, and
associated splicing connections, splice boxes and bolts to be installed as part
of a Project.

"Class "A" Assets" shall have the meaning specified in Section 6.2.

"Class "B" Assets" shall have the meaning specified in Section 6.2.

"Fiber/Cayer" means 360Cayer for rights and obligations relating to that part of
any Project which is located in Quebec, and 360fiber for rights and obligations
relating to that part of any Project which is not located in Quebec, and either
or both of them, as the context may require, for sections of general
application.

"Force Majeure" means in relation to the performance of any obligation under
this Agreement any cause, condition or event of any nature whatsoever which is
not reasonably foreseeable at the time this Agreement is executed and which is
beyond the reasonable control of the party responsible for performance of such
obligation and not caused in whole or in part by its default, and which prevents
in whole or in part the performance by that party of its respective obligations
under this Agreement, and includes without limitation, acts of war, revolution,
riot, sabotage, vandalism, changes in governmental regulation, earthquakes,
storms, lightning, weather conditions that impede construction (including,
without limitation, the ground freezing before it would ordinarily do so) and
other Acts of God, local or national emergencies, rail accidents, strikes, third
party lockouts, work slowdowns and other labour disputes, delays in obtaining
approvals or inspections by third parties, any claim or other interference by
First Nations, delays in obtaining Underlying Rights, issues relating to
Underlying Rights that prevent or delay the performance of work by Fiber/Cayer
and decreased availability of track time from that expected by Fiber/Cayer.

"Initial Term" shall have the meaning specified in Section 3.4.

"Notice of Non-Acceptance" shall have the meaning specified in Section 5.4.

                                     - 2 -
<PAGE>

"Notice of Completion" shall have the meaning specified in Section 5.4.

"Person" means an individual, partnership, corporation (including a business
trust), joint stock company, trust, unincorporated association, joint venture or
other entity or a foreign state or political subdivision thereof or any agency
of such state or subdivision.

"Projects" means all of the projects undertaken by the parties pursuant to this
Agreement for the development of telecommunications facilities in Canada and, in
respect of a particular Project, means all of the Cables, conduits and all
appurtenances thereto installed on the Underlying Rights relating thereto, and
"Project" means any of the Projects.

"Project Costs" means, with respect to a particular Project, all costs that are
incurred by 360fiber for the design, engineering, construction and installation
of such Project including, but not limited to, the Underlying Rights Costs.

"Project Specifications" means, with respect to a particular Project, the
engineering, design and operational specifications for the telecommunications
facilities that are to be developed as part of the Project, that are then
approved by 360, Fiber/Cayer and Urbanlink, acting reasonably and in good faith.

"Reasonable Efforts" shall mean efforts commercially and reasonably designed to
achieve the desired results, but shall not obligate a party to make unreimbursed
expenditures that are substantial in amount, in light of the circumstances to
which the requirement to use reasonable efforts applies.

"Segment" shall mean a longitudinal section of installed conduits.

"System" shall mean, with respect to a particular Project, the
telecommunications facility consisting of conduits, Cables and all appurtenances
thereto, developed or to be developed for such Project.

"Underlying Rights" means, with respect to a particular Project, all licenses,
leases, easements, rights-of-way, deeds, franchises, permits, authorizations,
consents and approvals (including, without limitation, any necessary local,
provincial, federal or First Nations authorizations and environmental permits)
and other rights, titles or interests as are necessary for the construction,
installation, operation, maintenance or repair of the System developed or to be
developed for such Project.

"Underlying Rights Costs" means, with respect to a particular Project, all
amounts expended by 360fiber to obtain the Underlying Rights and any renewals
thereof, including any charges for administrative costs incurred by 360fiber.

"Underlying Rights Requirements" means the terms, conditions, requirements,
restrictions, and/or limitations upon the parties' right to access, operate,
use, transfer or otherwise deal with the System imposed under the Underlying
Rights and the associated safety, operational and other rules and regulations
imposed in connection therewith or by applicable law.

                                     - 3 -
<PAGE>

                                   ARTICLE 2
                                 CO-DEVELOPMENT

2.1      CO-DEVELOPMENT

Urbanlink agrees with 360 and Fiber/Cayer that Urbanlink shall provide to
Fiber/Cayer the first option to have any telecommunications facilities developed
by Urbanlink in Canada (including, without limitation, (x) the facilities known
as the City Builds and (y) the portion of the facilities on the terrestrial
build between Seattle and Vancouver, which portion is located in British
Columbia) developed as Projects under this Agreement.

                                   ARTICLE 3
                           OBLIGATIONS OF FIBER/CAYER

3.1      ENGINEERING AND CONSTRUCTION

Fiber/Cayer shall engineer, design, install and construct the Projects on behalf
of Urbanlink and 360, in compliance with the Project Specifications, applicable
laws and all applicable Underlying Rights Requirements. Fiber/Cayer shall supply
all vehicles, tools, equipment, labour and similar items and services necessary
for Fiber/Cayer to perform and complete the Project. Fiber/Cayer shall procure
all materials to be incorporated in and to become a permanent part of the system
or the project.

3.2      SYSTEM ROUTE

Urbanlink shall determine the specific route and location of the System for a
Project using advice from Fiber/Cayer on industry knowledge of dark fiber
demand; provided however that the route for such System will generally connect
to the locations agreed upon by Fiber/Cayer and Urbanlink for such project,
acting reasonably and in good faith.

3.3      CONTRACTORS

Fiber/Cayer may assign or subcontract to a third party any or all of the duties
or obligations of Fiber/Cayer under this Agreement, provided that Fiber/Cayer
shall remain obligated to Urbanlink under the terms of this agreement for any
such duties.

3.4      UNDERLYING RIGHTS

Fiber/Cayer shall obtain all Underlying Rights (other than municipal access
agreements, as provided in Section 4.2) that are reasonably necessary in order
to (i) permit Fiber/Cayer to construct, install, maintain and convey to
Urbanlink the system hereunder, (ii) permit Urbanlink and its successors to use,
own, operate, access and maintain the system as provided and permitted
hereunder, and (iii) permit Urbanlink to grant sublicenses or sub-easements, as
the case may be, to third parties, all in accordance with the terms and
conditions hereof and in accordance with the Underlying Rights Requirements.
Fiber/Cayer shall use Reasonable Efforts to require that the initial stated term
of any Underlying Rights shall be for a period that does not expire in
accordance with its ordinary terms within 25 years of its effective date, or
such other

                                     - 4 -
<PAGE>

period as may then be agreed upon by Fiber/Cayer and Urbanlink, acting
reasonably and in good faith (the "Initial Term").

3.5      CHANGE REQUESTS

Fiber/Cayer or Urbanlink may request a change to the Project Specifications. The
other parties shall act reasonably and in good faith in considering any such
request.

3.6      INSPECTION BY URBANLINK

Urbanlink shall at all times the right to observe and inspect the performance by
Fiber/Cayer of the work to develop the Project.

3.7      ELECTRONICS

Urbanlink acknowledges that Fiber/Cayer is not supplying nor is Fiber/Cayer
obligated to supply to Urbanlink any optronics or electronics or optical or
electrical equipment of other similar facilities, all of which are the sole
responsibility of Urbanlink.

3.8      AS-BUILT DRAWINGS

As soon as reasonably practicable after the completion of a Project, Fiber/Cayer
shall provide to Urbanlink As-Built Drawings for the Project.

3.9      NO LIENS

At the time Fiber/Cayer transfers the ownership of and title to each Segment of
the Project to Urbanlink, the System shall be free and clear of all liens,
mortgages, security interests and encumbrances that may arise from any act or
omission of Fiber/Cayer.

3.10     WARRANTIES

On the completion of a Project, Fiber/Cayer shall cause all warranties received
by Fiber/Cayer from material suppliers, equipment makers or contractors to be
assigned to Urbanlink to the extent of Urbanlink's interest in the Project,
wherever practicable, and shall furnish to Urbanlink written evidence of such
assignment, or otherwise assist Urbanlink in enforcing same. Where such
assignment is impracticable or affects the retained interest of Fiber/Cayer in
the Project, Fiber/Cayer shall then hold such warranties in trust for the
benefit of Urbanlink and all other interested persons.

3.11     LIMITED WARRANTY

For a period of 12 months following the acceptance of the System for a Project,
Fiber/Cayer warrants that the engineering, design, construction and installation
of the System will be in compliance with the Project Specifications. Upon the
termination of the 12 month warranty, Urbanlink shall have no further recourse
against Fiber/Cayer or 360 with respect to the engineering, design, construction
and installation of the System, except for any claims made during such warranty
period, for which Fiber/Cayer shall remain responsible.

                                     - 5 -
<PAGE>

3.12     CERTAIN WARRANTIES EXCLUDED

EXCEPT AS SET FORTH IN SECTION 3.11, OR AS MAY OTHERWISE BE SET FORTH
SPECIFICALLY AND EXPRESSLY ELSEWHERE IN THIS AGREEMENT, FIBER/CAYER AND 360 MAKE
NO WARRANTY OR CONDITION, EXPRESSED OR IMPLIED, WITH RESPECT TO THE SYSTEM OR
ANY SERVICES PROVIDED TO URBANLINK PURSUANT HERETO, INCLUDING ANY WARRANTY OR
CONDITION OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR USE, AND ALL
SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. THE WARRANTIES SET FORTH IN
THIS AGREEMENT CONSTITUTE THE ONLY WARRANTIES MADE BY FIBER/CAYER OR 360 TO
URBANLINK WITH RESPECT TO THIS AGREEMENT AND ARE MADE IN LIEU OF ALL OTHER
WARRANTIES OR CONDITIONS, WRITTEN OR ORAL, STATUTORY, EXPRESSED OR IMPLIED.

                                   ARTICLE 4
                            OBLIGATIONS OF URBANLINK

4.1      COMPLIANCE WITH LAWS

Urbanlink shall be solely responsible for compliance with all legal and
regulatory requirements associated with its business or with ownership or
operation of the Systems including, without limitation, obtaining, maintaining
and paying for any and all regulatory permits, franchises, authorizations,
licences, consents or approvals that are required for Urbanlink's ownership, use
and operation of the Systems, and Fiber/Cayer shall have no responsibility or
liability whatsoever in connection therewith.

4.2      MUNICIPAL ACCESS AGREEMENTS

Without limiting the generality of Section 4.1, Urbanlink shall obtain, at its
own cost and expense, all municipal access agreements as may be required with
respect to the installation, construction or placement of the System by
Fiber/Cayer or with respect to Urbanlink's ownership, use and operation of the
System.

                                   ARTICLE 5
                          NORMAL RIGHTS AND OBLIGATIONS

5.1      PROJECT TEAM

Each of 360, Fiber/Cayer and Urbanlink shall designate employees to be members
of a project team for each Project, to facilitate and coordinate activities
under this Agreement. In addition, 360, Fiber/Cayer and Urbanlink shall
designate one or more individuals as onsite inspectors to monitor construction
progress. Fiber/Cayer shall convene periodic meetings of the project team to
review the progress of the work relating to a Project, such meetings to be held
at the principal office of Fiber/Cayer or at such other place as may be agreed
upon between the parties, acting reasonably and in good faith. The parties agree
that such meetings may be convened by means of a telephone conference or other
communications facility whereby all representatives participating in the meeting
can hear each other and communicate with each other.

                                     - 6 -
<PAGE>

5.2      COMPLIANCE WITH UNDERLYING RIGHTS

Each of the parties covenants and agrees with the others to comply with and to
observe and perform their respective duties, obligations and responsibilities
under the Underlying Rights and under this Agreement. Throughout the term of
each of the Underlying Rights, each of the parties shall defend and protect
their collective rights and interests under the Underlying Rights and their
collective and individual rights to use the System as provided and permitted
hereunder against interfering or infringing rights, interests or claims of third
parties. The costs incurred in defending and protecting such rights and
interests shall be shared between Fiber/Cayer and Urbanlink in such proportions
as may then be agreed between them, acting reasonably and in good faith.

5.3      RISK OF LOSS

Fiber/Cayer shall bear all risks of loss to the System until title is
transferred, and Urbanlink shall bear all risks of loss to the System
thereafter.

5.4      COMPLETION AND ACCEPTANCE

The following acceptance procedures shall apply:

         (a)      Fiber/Cayer shall provide a written notice ("Notice of
                  Completion") to Urbanlink when Fiber/Cayer has completed the
                  System for a Project, including testing, and the System is
                  available for testing by Urbanlink. The Notice of Completion
                  shall include the test results obtained by Fiber/Cayer.

         (b)      Urbanlink shall have 14 days from the day Urbanlink receives
                  the Notice of Completion to determine whether the System is
                  constructed according the Project Specifications. Unless
                  Urbanlink gives notice in writing to Fiber/Cayer that the
                  System is not constructed according the Project
                  Specifications, clearly identifying the nature of the failure
                  by cross-reference to such Project Specifications (hereinafter
                  referred to as the "Notice of Non-Acceptance") within 14 days
                  of receiving the Notice of Completion as described above,
                  Urbanlink shall be deemed to have accepted the System.

         (c)      If Urbanlink gives a Notice of Non-Acceptance, Fiber/Cayer
                  shall have 30 days from the day Fiber/Cayer receives the
                  Notice of Non-Acceptance to remedy the defect and cause the
                  System to be constructed according to the Project
                  Specifications, or such longer period as may reasonably be
                  required for that purpose. The parties shall work together in
                  good faith to promptly identify those items that require
                  correction.

         (d)      Upon the expiration of the period referred to in Section
                  5.4(c), or upon notice from Fiber/Cayer that the conditions
                  identified in the Notice of Non-Acceptance had been corrected,
                  whichever occurs first, Urbanlink shall have an additional
                  seven day period to determine whether the System is
                  constructed according to the Project Specifications.

                                     - 7 -
<PAGE>

         (e)      If Fiber/Cayer has failed to remedy the failure to meet the
                  Project Specifications identified in the Notice of
                  Non-Acceptance, and such failure remains unresolved at the end
                  of the 30 day period referred to in Section 5.4(c), the
                  parties shall have recourse to dispute resolution in
                  accordance with the terms of this Agreement.

5.5      FORCE MAJEURE

In no event shall Fiber/Cayer be liable to Urbanlink for any non-performance or
breach of contract, or for any costs, losses or damages including, without
limitation, loss of profit or consequential damages of any type whatsoever,
which arise by reason of or under conditions of Force Majeure. Fiber/Cayer shall
give notice to Urbanlink of any event of Force Majeure and shall use Reasonable
Efforts to remedy same or the causes thereof.

5.6      NO CONSEQUENTIAL DAMAGES

Neither 360 nor Fiber/Cayer shall be liable to Urbanlink, and Urbanlink shall
not be liable to either 360 or Fiber/Cayer, for any special, indirect, punitive,
or consequential damages including, but not limited to, loss of profits or
revenue, cost of capital, or claims of contractors, suppliers, clients or
customers (whether arising out of transmission interruptions or problems, any
interruption or degradation of service, or otherwise), whether foreseeable or
not, arising out of, or in connection with, any breach of this Agreement or any
document delivered pursuant to this Agreement, or breach of contract, breach of
warranty, tort, negligence, strict liability or any other theory of liability
relating to the subject matter of this Agreement or of any other document
delivered pursuant to this Agreement, or to the liable party's performance or
non-performance of its obligations under this Agreement or any document
delivered pursuant to this Agreement, and all claims with respect to such
indirect, punitive or consequential damages are hereby specifically waived and
released.

5.7      LIMIT ON DAMAGES

Notwithstanding any other provision of this Agreement, Fiber/Cayer shall not be
liable to Urbanlink for any breach hereof, or any claim of any nature
whatsoever, in excess of 10% of the Project Costs for the Project in respect of
which the claim is made. This Section shall not form the basis of any claim
against Fiber/Cayer in and of itself, and shall not increase or enlarge the
liability of Fiber/Cayer established pursuant to the other terms of this
Agreement or otherwise.

5.8      TIME LIMITATION

Urbanlink shall not make any claim for losses or damages whatsoever in
connection with this agreement more than two years after the date that the event
giving rise to such claim is known or reasonably should have been known to
Urbanlink.

5.9      TAXES

The parties agree to negotiate in good faith with a view to minimizing any taxes
that may be due or become due in connection with the Projects. The parties
acknowledge that this may involve, among other things, amendments to the terms
of this Agreement. Notwithstanding the foregoing, all taxes, assessments or
other fees associated with the Systems shall be the sole responsibility of

                                     - 8 -
<PAGE>

Urbanlink, including but not limited to all sales taxes and all taxes, other
than taxes measured by net income, imposed on Fiber/Cayer or 360 with respect to
the sale, lease, ownership, use or operation of the System. All taxes required
by applicable law to be paid or remitted by Fiber/Cayer or 360 shall be
separately stated on invoices or statements to Urbanlink to the extent permitted
by applicable law.

5.10     INSURANCE

For each Project, Fiber/Cayer and Urbanlink shall each obtain and maintain such
insurance coverage as may then be agreed between Fiber/Cayer and Urbanlink,
acting reasonably and in good faith.

5.11     CONFIDENTIALITY

The parties understand and agree that this Agreement, any documents delivered
pursuant to this Agreement, and all materials, maps, engineering designs and
documents, construction techniques, pricing and other information as may be
necessarily exchanged between them in fulfilling the provisions and intents of
this Agreement, are and shall be confidential. For greater clarity, the
obligations of the parties shall extend to and include all such information as
may be supplied by the grantors of Underlying Rights, and whether directly
supplied by such grantor or supplied by any party. Each party shall ensure that
its Subsidiaries, Affiliates, Associates, directors, officers and employees
shall keep secret all such confidential information of the other party and all
other information which has been clearly identified in advance as confidential
by the other party including, without limitation, this Agreement, shall not
disclose any such confidential information except as authorized by the other
party and shall not use such confidential information except in connection with
this Agreement. This obligation shall continue to bind any party after it shall
cease to be a party for whatever reason and shall survive termination of this
Agreement but such obligation of confidentiality shall not apply:

         (a)      to a disclosure to a person who knew the confidential
                  information prior to its being disclosed;

         (b)      to a disclosure of information which comes into the public
                  domain without any breach of the provisions of this Section;

         (c)      to disclosure of information which is disclosed on a
                  confidential basis to consultants or advisers of a party who
                  have a bona fide need to know to assist that party in the
                  carrying out of the terms of this Agreement;

         (d)      to a disclosure of information which is disclosed to any
                  governmental authority or court having jurisdiction over any
                  aspect of the performance of this Agreement;

         (e)      to a disclosure of information which is disclosed in
                  arbitration, regulatory or court proceedings taken by either
                  party for the enforcement of any of its rights and remedies
                  under this Agreement;

         (f)      to a disclosure in performance of one's obligations (or those
                  of its Affiliates) as a public company;

                                     - 9 -
<PAGE>

         (g)      to a disclosure in connection with the sale or other transfer
                  of rights or strands, to a proposed acquirer of such rights or
                  strands provided the proposed acquirer has executed an
                  appropriate form of confidentiality agreement; or

         (h)      to a disclosure on a confidential basis in connection with
                  any financing.

5.12     PATENTS AND COPYRIGHTS

Urbanlink acknowledges the rights of Fiber/Cayer, 360 and certain Affiliates of
360 to certain patents, copyrights and materials that Fiber/Cayer may use in the
performance of its obligations under this Agreement, acknowledges that is has no
interest in such rights and that no interest in such rights passes under this
Agreement or in any other manner, and agrees to use its reasonable efforts to
protect such rights in dealing with third parties.

                                   ARTICLE 6
                               COSTS AND BENEFITS

6.1      PROJECT COSTS

As its contribution to a Project, Fiber/Cayer shall pay * Project Costs of the
Project.

6.2      LEGAL TITLE AND RIGHT OF USE

Upon completion of each material segment of a Project and payment of *
Project Costs pursuant to Section 6.1, title in such segment shall pass to
Urbanlink, subject to Fiber/Cayer's right to retain in accordance with
Section 6.4 hereof * proceeds from the sale, lease, granting of IRU's or any
similar interests with respect to, or other commercial exploitation of, *
strands of the system constructed by Fiber/Cayer. The * strands retained by
Urbanlink shall be specifically identified by Fiber/Cayer and Urbanlink upon
the completion of a segment (such * strands are herein called the "Class A
Assets", and all of the telecommunications facilities of the System, other
than the Class A Assets, are herein called the "Class B Assets"). To ensure
that Urbanlink remits such proceeds to Fiber/Cayer, Urbanlink shall grant to
Fiber/Cayer an IRU in the Class B Assets. Fiber/Cayer agrees to surrender
this IRU upon receipt of the proceeds from the commercial exploitation of the
Class B Assets or to surrender or assign the same to Urbanlink upon Urbanlink
paying Fiber/Cayer the fair market value of the Class B Assets.

6.3      * OF THE CLASS B ASSETS

Urbanlink shall use Reasonable Efforts to * the Class B Assets, at *. If so
required by notice in writing from Fiber/Cayer, Urbanlink shall * all or any
part of the Class B Assets specified in such notice to the person or persons
specified in such notice * specified in such notice.

                                     - 10 -
<PAGE>

6.4      DEEDS OF SALE

* proceeds from the sale, lease, granting of IRUs or similar interests or
other exploitation of the Class B Assets, less a margin of *, shall be paid
by Urbanlink to Fiber/Cayer forthwith on the receipt of such proceeds by
Urbanlink.

6.5      INTEREST IN DEFAULT

If Urbanlink fails to pay to Fiber/Cayer any amount when such payment is due,
Urbanlink shall also pay to Fiber/Cayer interest on the unpaid amount from the
date payment is due until the date payment is made at a rate equal to 1.5% per
month, compounded monthly (equivalent to 19.56% per annum).

6.6      SECURITY AGREEMENT

If, in the opinion of Fiber/Cayer, acting reasonably and in good faith, it is
necessary or desirable that Urbanlink grant to Fiber/Cayer a security interest
in the Class B Assets, then Urbanlink shall execute and deliver to Fiber/Cayer a
security agreement in such form and on such terms as Fiber/Cayer may request,
acting reasonably and in good faith.

                                   ARTICLE 7
                              TERM AND TERMINATION

7.1      TERM

The terms of this Agreement will commence on the date of this Agreement and will
continue for ten years.

7.2      SURVIVAL OF TERMS

Sections 4.1, 4.2, 5.2, 5.6, 5.7, 5.8, 5.9, 5.11, 5.12, 6.2, 6.3, 6.4, 6.5, 7.2
and 8.1 to 8.17 inclusive shall survive the expiration or termination of this
Agreement and will remain in full force and effect following such expiration or
termination. The expiration or termination of this Agreement will not affect the
rights of any party to make a claim for damages arising from a breach of any
provision of this Agreement which occurred prior to such expiration or
termination.

                                   ARTICLE 8
                                     GENERAL

8.1      DISPUTE RESOLUTION

If the parties are unable to resolve any disagreement or dispute arising under
or relating to this Agreement including, without limitation, the failure to
agree upon any item requiring the mutual agreement of the parties hereunder,
they shall resolve the disagreement or dispute as follows:

         (a)      The parties shall first attempt to settle such dispute by
                  mutual discussion between the members of the project team.

*  Material omitted and filed separately with the Securities and Exchange
   Commission pursuant to a request for confidential treatment under Rule 246-2
   of the Securities Exchange Act of 1934, as amended.

                                     - 11 -
<PAGE>

         (b)      If the matter has not been resolved by the mutual discussion
                  required by subsection (a) within 30 Business Days after the
                  date on which the dispute arose, then the parties shall
                  attempt to settle such dispute by mutual discussion between
                  the President of Urbanlink and the President or a Senior
                  Vice-President of 360.

         (c)      If the matter has not been resolved by the mutual discussion
                  required by subsection (b) within 60 Business Days after which
                  the dispute arose, then such dispute shall finally be resolved
                  by arbitration pursuant to Section 8.2 of this Agreement.

8.2      ARBITRATION

All disputes arising out of or in correction with this contract, or in respect
of any defined legal relationship associated therewith or derived therefrom
(except for disputes arising out of the terms provided in Schedule A), shall be
referred to and finally resolved by arbitration under the Rules of the British
Columbia International Commercial Arbitration Centre. The appointing authorities
shall be the British Columbia International Commercial Arbitration Centre. The
case shall be administered by the British Columbia International Commercial
Arbitration Centre in accordance with its "Procedures for Cases Under the BCICAC
Rules". The place of arbitration shall be Vancouver, British Columbia, Canada.

8.3      GOVERNING LAW AND ATTORNMENT

This Agreement will be governed by and construed in accordance with the
substantive laws of British Columbia and the federal laws of Canada applicable
in British Columbia, without regard to the conflict of law rules of British
Columbia. Subject to Section 8.2, the parties irrevocably submit to and accept
generally and unconditionally the exclusive jurisdiction of the courts and
appellate courts of British Columbia with respect to any legal action or
proceeding which may be brought at any time relating in any way to this
Agreement. Each of the parties irrevocably waives any objection it may now or in
the future have to the venue of any such action or proceeding, and any claim it
may now or in the future have that any such action or proceeding has been
brought in an inconvenient forum.

8.4      TIME OF THE ESSENCE OF THE AGREEMENT

Unless otherwise specifically provided in this Agreement, time will be of the
essence of this Agreement and of the transactions contemplated by this
Agreement.

8.5      REMEDIES NOT EXCLUSIVE

The remedies provided to the parties under this Agreement are cumulative and not
exclusive to each other, and any such remedy will not be deemed or construed to
affect any right which any of the parties is entitled to seek at law, in equity
or by statute.

                                     - 12 -
<PAGE>

8.6      NOTICES

Any notice, direction, request or other communication required or contemplated
by any provision of this Agreement will be given in writing and will be given by
delivering or faxing or emailing the same to the parties as follows:

         (a)      To 360 at:

                  Suite 1500, 1066 West Hastings Street
                  Vancouver, B.C. V6E 3X1

                  Attention:        Catherine McEachern
                  Fax No.:          (604) 681-0994
                  Email:            catherine.mceachern@360.net

         (b)      To Fiber/Cayer at:

                  Suite 1500,1066 West Hastings Street
                  Vancouver, B.C. V6E 3X1

                  Attention:        Catherine McEachern
                  Fax No.;          (604) 681-0994
                  Email:            catherine.mceachern@360.net

         (c)      To Urbanlink at:

                  Suite 1000, 1066 West Hastings Street
                  Vancouver, B.C. V6E 3X1

                  Attention:        Ray Hazlett
                  Fax No.:          (604) 681-5372
                  Email:            ray.hazlett@ledcor.com

Any such notice, direction, request or other communication will be deemed to
have been given or made on the date on which it was delivered or, in the case of
fax or email, on the next business day after receipt of transmission. Any party
may change its fax number or address for service or email address from time to
time by written notice in accordance with this section.

8.7      ASSIGNMENT

         (a)      This Agreement is not assignable by Urbanlink in whole or in
                  part without the prior written consent of 360, such consent
                  not to be unreasonably delayed. This Agreement is not
                  assignable by 360 or Fiber/Cayer without the prior written
                  consent of Urbanlink, such consent not to be unreasonably
                  delayed. Any attempt by any party to assign any of the rights
                  or to delegate any of the duties or obligations of this
                  Agreement without such prior written consent is void.

                                     - 13 -
<PAGE>

         (b)      Notwithstanding the foregoing, the interests of any party may
                  be assigned by such party to an Affiliate, provided that such
                  Affiliate delivers to the other parties a written undertaking
                  to be bound by the provisions of this Agreement in all
                  respects and to the same extent as the assignor is bound and
                  provided further that the assignor will continue to be bound
                  by all the obligations hereunder as if such assignment had not
                  occurred and shall perform such obligations to the extent that
                  such Affiliate fails to do so.

         (c)      Notwithstanding the foregoing, the interests of a party under
                  this Agreement (including, without limitation, in the case of
                  Fiber/Cayer, the right to receive any and all amounts payable
                  to Fiber/Cayer under this Agreement) may be assigned by such
                  party by way of collateral security to a lender without the
                  consent of the other parties, provided however that any such
                  lender agrees in writing that:

                  (i)      the rights and interest of the lender are subject to
                           the rights and interests of the parties other than
                           the assignor under this Agreement;

                  (ii)     prior to realizing on such collateral security it
                           will provide notice to the other parties giving them
                           the opportunity to cure the default; and

                  (iii)    should such security be realized with the result that
                           the title or interest of the assignor, as the case
                           may be, is vested in an assignee, acquirer or other
                           successor in title or interest (including the lender
                           if such is the case) ("Successor"), then the lender
                           will cause such Successor to enter into a written
                           agreement with the other parties to be bound by the
                           provisions of this Agreement in all respects and to
                           the same extent as the assignor was bound and this
                           from the date the title or interest is transferred
                           and provided further that the assignor will continue
                           to be bound by all the obligations under this
                           Agreement as if such transfer of title or interest
                           had not occurred and will perform such obligations to
                           the extent that the Successor fails to do so.

8.8      WAIVER

No failure or delay on the part of any party in exercising any power or right
under this Agreement will operate as a waiver of such power or right. No single
or partial exercise of any right or power under this Agreement will preclude any
further or other exercise of such right or power. No modification or waiver of
any provision of this Agreement and no consent to any departure by any party
from any provision of this Agreement will be effective until the same is in
writing. Any such waiver or consent will be effective only in the specific
instance and for the specific purpose for which it was given. No notice to or
demand on any party in any circumstances will entitle such party to any other or
further notice or demand in similar or other circumstances.

                                     - 14 -
<PAGE>

8.9      FURTHER ASSURANCES

Each of the parties will promptly execute and deliver to the other at the cost
of the other such further documents and assurances and take such further actions
as the other may from time to time request in order to more effectively carry
out the intent and purpose of this Agreement and to establish and protect the
rights, interests and remedies intended to be created in favour of the other.

8.10     ENTIRE AGREEMENT

This Agreement and any documents and agreements to be delivered pursuant to this
Agreement supersede all previous invitations, proposals, letters,
correspondence, negotiations, promises, agreements, covenants, conditions,
representations and warranties with respect to the subject matter of this
Agreement. There is no representation, warranty, collateral term or condition or
collateral agreement affecting this Agreement, other than as expressed in
writing in this Agreement.

8.11     AMENDMENTS

No change or modification of this Agreement will be valid unless it is in
writing and signed by each party to this Agreement.

8.12     INVALIDITY OF PARTICULAR PROVISIONS

If any provision of this Agreement or any part of any provision (in this section
called the "Offending Provision") is declared or becomes unenforceable, invalid
or illegal for any reason whatsoever including, without limiting the generality
of the foregoing, a decision by any competent courts, legislation, statutes,
bylaws or regulations or any other requirements having the force of law, then
the remainder of this Agreement will remain in full force and effect as if this
Agreement had been executed without the Offending Provision.

8.13     CURRENCY

Unless otherwise specified all sums of money expressed in this Agreement are in
the lawful money of Canada.

8.14     NUMBER AND GENDER

Unless the context of this Agreement otherwise requires, to the extent necessary
so that each clause will be given the most reasonable interpretation, the
singular number will include the plural and vice versa, the verb will be
construed as agreeing with the word so substituted, words importing the
masculine gender will include the feminine and neuter genders, words importing
persons will include firms and corporations and words importing firms and
corporations will include individuals.

                                     - 15 -
<PAGE>

8.15     HEADINGS AND CAPTIONS

The headings and captions of sections and paragraphs contained in this Agreement
are all inserted for convenience of reference only and are not to be considered
when interpreting this Agreement.

8.16     ACKNOWLEDGEMENT OF RECEIPT

Each of the parties acknowledges receiving an executed copy of this Agreement.

8.17     PERFORMANCE

360Cayer shall perform all of Fiber/Cayer's obligations under this Agreement in
Quebec, and 360fiber shall perform all of Fiber/Cayer's obligations outside of
Quebec.

8.18     AMENDED AND RESTATED AGREEMENT

This Agreement is an amended and restated version of the original Co-Development
Agreement dated as of April 17, 2000 and made between the undersigned parties.
The parties acknowledge and agree that the original Co-Development Agreement is
superceded by the terms of this Amended and Restated Co-Development Agreement,
with effect as of the date of this Agreement. For greater clarity and the
avoidance of doubt, the original Co-Development Agreement shall continue to have
effect to govern the rights and obligations of the parties for the period from
April 17, 2000 to the expiry of the day before the date of this Agreement.

8.19     ENUREMENT

Subject to the restrictions on transfer contained in this Agreement, this
Agreement will enure to the benefit of and be binding on the parties and their
respective heirs, executors, administrators, successors and assigns.

                     [THE NEXT PAGE IS THE EXECUTION PAGE.]

                                     - 16 -
<PAGE>

IN WITNESS WHEREOF the parties have executed this Agreement as of the date
stated on the first page.

360NETWORKS INC.                       360FIBER LTD.
Per:                                   Per:
Signed                                 Signed
----------------------------           ----------------------------
Signature                              Signature

WFI URBANLINK LTD.                     360CAYER LTEE.
Per:                                   Per:
Signed                                 Signed
----------------------------           ----------------------------
Signature                              Signature

                                     - 17 -<PAGE>

                                                                 EXHIBIT 4.26

                              AMENDED AND RESTATED
                             SHAREHOLDERS AGREEMENT

                                  by and among

                                360NETWORKS INC.

                                     DWF SRL

                          GS CAPITAL PARTNERS III, L.P.

                            GSCP3 WWF (BARBADOS) SRL

                               WWF (BARBADOS) SRL

                          PROVIDENCE EQUITY FIBER, L.P.

                               TYCO GROUP S.A.R.L.

                          WORLDWIDE FIBER HOLDINGS LTD.

                                   LEDCOR INC.

                                       and

                  THE SEVERAL SHAREHOLDERS NAMED IN SCHEDULE I

                                   dated as of

                                 April 20, 2000

                                     - 1 -

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>

<S>     <C>                                                                                                      <C>
SECTION 1. Certain Definitions....................................................................................2
SECTION 2. Methodology for Calculations...........................................................................4
SECTION 3. Corporate Governance...................................................................................4
         3.1      Board of Directors..............................................................................4
         3.2      Vacancies; Removal..............................................................................5
         3.3      Quorum..........................................................................................5
         3.4      Directors' Indemnification......................................................................6
         3.5      No Expansion of Duties..........................................................................6
         3.6      Expenses.  .....................................................................................7
         3.7      Appointment of Senior Officers..................................................................7
         3.8      Shareholder Voting Arrangement..................................................................7
SECTION 4. Representations and Warranties.........................................................................8
SECTION 5. Certain Covenants......................................................................................9
         5.1      Protection of Investors.........................................................................9
         5.2      System of Accounting............................................................................9
         5.3      Compliance with Laws............................................................................9
         5.4      Insurance.......................................................................................9
         5.5      Licenses and Permits............................................................................9
         5.6      Disclosure of Investment........................................................................9
SECTION 6. Confidentiality.......................................................................................10
SECTION 7. Specific Performance; Injunction......................................................................11
SECTION 8. No Inconsistent Agreements.  .........................................................................11
SECTION 9. Further Assurances.  .................................................................................12
SECTION 10. Contractual Management Rights........................................................................12
SECTION 11. Severability.........................................................................................12
SECTION 12. Governing Law; Waiver of Jury Trial..................................................................12
SECTION 13. Condition to Effectiveness; Successors and Assigns...................................................13
SECTION 15. Amendments...........................................................................................17
SECTION 16. Headings.............................................................................................17
SECTION 17. Nouns and Pronouns...................................................................................17
SECTION 18. Entire Agreement.....................................................................................18
SECTION 19. Counterparts.........................................................................................18
SECTION 20. No Partnership.......................................................................................18
SECTION 21. Ledcor Assurances....................................................................................18
</TABLE>

                                     - i -
<PAGE>

                              AMENDED AND RESTATED
                             SHAREHOLDERS AGREEMENT

          This AMENDED AND RESTATED SHAREHOLDERS AGREEMENT (the "Agreement"),
dated as of April 20, 2000, by and among 360NETWORKS INC. (formerly called
WORLDWIDE FIBER INC.), a corporation continued under the laws of Nova Scotia
(the "Corporation"), DWF SRL, a Barbados company ("DLJ"), GS CAPITAL PARTNERS
III, L.P., a Delaware limited partnership ("GSCP") (signatory hereto solely for
purposes of Section 3), GSCP3 WWF (Barbados) SRL, a Barbados company, WWF
(Barbados) SRL, a Barbados company, each of which is an affiliate of The Goldman
Sachs Group, Inc. (collectively, with GSCP, the "GSCP Parties"), PROVIDENCE
EQUITY FIBER, L.P., a Delaware limited partnership, ("Providence"), TYCO GROUP
S.a.r.l., a Luxembourg corporation ("Tyco") (collectively with DLJ, the GSCP
Parties and Providence, the "Investors") WORLDWIDE FIBER HOLDINGS LTD., an
Alberta corporation ("WFH"), LEDCOR INC., an Alberta corporation ("Ledcor")
(signatory hereto solely for purposes of the Sections specified in Section 21),
and the signatories listed on Schedule I hereto.

                              W I T N E S S E T H :

          WHEREAS, the parties hereto are parties to that certain Shareholders
Agreement, dated as of September 9, 1999 as amended by that certain Amending and
Waiver Agreement dated December 22, 1999, that certain Joinder to the
Shareholders Agreement dated as of March 6, 2000 and that certain Second
Amending Agreement dated as of March 9, 2000 (the "Prior Shareholders
Agreement").

          WHEREAS, the Corporation and the Investors are parties to that certain
Preferred Share Purchase Agreement, dated as of September 7, 1999 as
supplemented by the Amending and Waiver Agreement dated December 22, 1999 and
the Adjustment of Shares Agreement dated March 6, 2000 (the "Purchase
Agreement"), pursuant to which the Corporation has issued to the Investors, and
the Investors have purchased from the Corporation, shares of a series of
Preferred Shares (the "Series A Non-Voting Preferred Shares").

          WHEREAS, the Corporation is contemplating a public offering pursuant
to the prospectus dated April 19, 2000 (the "Public Equity Offering") and the
parties hereto desire immediately upon the consummation of that public offering
to amend and restate the Shareholders Agreement in its entirety to establish and
set forth their agreement with respect to certain rights and obligations
associated with ownership of Shares (as defined below).

                                      - 1-
<PAGE>

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

          SECTION 1. Certain Definitions. As used herein, the following terms
shall have the following meanings (capitalized terms used herein and not
otherwise defined herein shall have the meanings assigned to such terms in the
Purchase Agreement):

          "Affiliate" shall mean (i) with respect to any Person, any other
Person directly or indirectly controlling or controlled by or under direct or
indirect common control with such specified Person, or (ii) with respect to any
individual, shall also mean the spouse, child (including a stepchild or an
adopted child), grandchildren, parent, brother, sister or other BONA FIDE estate
planning recipient thereof or any spouse of any of the foregoing, and each trust
created for the exclusive benefit of any one or more of them. Notwithstanding
the foregoing, neither the Corporation nor any Person controlled by the
Corporation shall be deemed to be an Affiliate of any Shareholder for purposes
of this Agreement.

          "Board" shall mean the Board of Directors of the Corporation.

          "Closing" means the closing of the Public Equity Offering.

          "Common Share Equivalents" shall mean all options, warrants and other
securities and obligations convertible into, or exchangeable or exercisable for,
at any time or upon the occurrence of any event or contingency and without
regard to any vesting or other conditions to which such securities may be
subject, Common Shares.

          "Common Shares" shall mean any common shares of the Corporation of any
class or series whether now or hereafter authorized, including without
limitation the Corporation's Subordinate Voting Shares and Multiple Voting
Shares and any shares into which such common shares may be exchanged,
reclassified, recapitalized, converted or otherwise.

          "Financial Investors" shall mean each of (i) DLJ, (ii) the GSCP
Parties and (iii) Providence, collectively.

          "In-The-Money Common Share Equivalents" shall mean, at any time, any
Common Share Equivalents as to which the effective price per Common Share
issuable upon conversion, exchange or exercise of such Common Share Equivalents
(determined by dividing (A) the sum of (x) the aggregate purchase price paid in
respect of such Common Share Equivalents plus (y) the aggregate amount payable
upon conversion, exchange or exercise of such Common Share Equivalents in order
to issue all Common

                                     - 2 -
<PAGE>

Shares issuable pursuant to such Common Share Equivalents by (B) the number of
Common Shares issuable upon the conversion, exchange or exercise of such Common
Share Equivalents) is equal to or less than the then fair market value per
Common Share as determined in good faith by the Board.

          "Ledcor" shall mean Ledcor Inc., a corporation incorporated under the
laws of Alberta.

          "Ledcor Entities" shall mean Ledcor Inc. and each of its Subsidiaries,
collectively, except for those entities which are defined as WFI Entities in the
Purchase Agreement.

          "Person" shall mean any individual, corporation, limited liability
company, limited or general partnership, joint venture, association, joint-stock
company, trust, unincorporated organization, other entity or government or any
agency or political subdivisions thereof.

          "Sell" shall mean, as to any Shares, to sell, or in any other way
directly or indirectly transfer, assign, distribute, pledge, encumber or
otherwise dispose of, either voluntarily or involuntarily, including the
assignment or transfer of voting rights attaching to such Shares (if any); the
terms Sale, Selling and Sold shall have meanings correlative to the foregoing.

          "Senior Officer" shall mean any of the individuals, numbering at least
five, who hold any of the following positions or their functional equivalents
irrespective of actual title held in the Corporation: (A) Chairman; (B)
Vice-Chairman; (C) Chief Executive Officer; (D) President; (E) Chief Financial
Officer; (F) Chief Operating Officer; and (G) Executive Vice President.

          "Shareholders" shall mean the parties to this Agreement (other than
the Corporation, GSCP or, except as specified in Section 21, Ledcor) and any
other Person who executes, and agrees to be bound by the terms of, this
Agreement.

          "Shares" shall mean (i) any Common Shares and (ii) any Common Share
Equivalents, in each case, whether owned or outstanding on the date hereof or
hereafter.

          "Subsidiary" shall mean with respect to any Person, any company,
partnership or other entity (i) of which at least a majority of the shares of
capital stock or other ownership interests having ordinary voting power to elect
a majority of the board of directors or other similar managing body of such
company, partnership or other entity are at the time owned or controlled,
directly or indirectly, by such Person or (ii) the management of which is
otherwise controlled, directly or indirectly, through one or more intermediaries
by such Person.

                                     - 3 -
<PAGE>

          SECTION 2. Methodology for Calculations. For purposes of this
Agreement, the Sale of a Common Share Equivalent (whether or not an In-The-Money
Common Share Equivalent) shall be treated as the Sale of the Common Shares into
which such Common Share Equivalent can be converted, exchanged or exercised.
Except as otherwise specifically provided in this Agreement, for purposes of all
calculations under this Agreement (including, without limitation, calculations
to determine the ownership of Common Shares of any Shareholder and the
percentage of outstanding Common Shares owned by any Shareholder), (without
duplication) all In-The-Money Common Share Equivalents, but no other Common
Share Equivalents, shall be treated as having been converted, exchanged or
exercised into or for Common Shares.

          SECTION 3. Corporate Governance.

          3.1    Board of Directors.

          (a) The Board shall have overall responsibility for managing and
supervising the management of the business and affairs of the Corporation, and
the power and authority of the directors shall be subject only to such
restrictions as are imposed by this Agreement and by applicable law.

          (b) The maximum number of members of the Board shall be seventeen
(17).

          (c) From and after the date hereof and until DLJ, together with its
Investor Affiliates, Sell 25% or more of the Shares issued to it pursuant to the
Purchase Agreement (as equitably adjusted to reflect any stock split, stock
dividend, combination, reorganization, recapitalization, reclassification or
other similar event involving Common Shares), DLJ shall have the right to
nominate one person (the "DLJ Nominee") to serve as a director on the Board.

          (d) From and after the date hereof and until the GSCP Parties,
together with their Investor Affiliates, Sell 25% or more of its Shares issued
to it pursuant to the Purchase Agreement (as equitably adjusted to reflect any
stock split, stock dividend, combination, reorganization, recapitalization,
reclassification or other similar event involving Common Shares), GSCP shall
have the right to nominate one person (the "GSCP Nominee") to serve as a
director on the Board.

          (e) From and after the date hereof and until Providence, together with
its Investor Affiliates, Sell 25% or more of the Shares issued to it pursuant to
the Purchase Agreement (as equitably adjusted to reflect any stock split, stock
dividend, combination, reorganization, recapitalization, reclassification or
other similar event involving Common

                                     - 4 -
<PAGE>

Shares), Providence shall have the right to nominate one person (the "Providence
Nominee") to serve as a director on the Board.

          (f) From and after the date hereof and until Tyco, together with its
Investor Affiliates, Sell 56% or more of the Shares issued to it pursuant to the
Purchase Agreement (as equitably adjusted to reflect any stock split, stock
dividend, combination, reorganization, recapitalization, reclassification or
other similar event involving Common Shares), Tyco shall have the right to
nominate one person (the "Tyco Nominee"; collectively with the DLJ Nominee, the
GSCP Nominee and the Providence Nominee, the "Investor Nominees"), to serve as a
director on the Board.

          (g) From and after the date hereof, the remaining members of the Board
(the "Non-Investor Nominees", collectively with the DLJ Nominee, the GSCP
Nominee, the Providence Nominee and the Tyco Nominee, the "Nominees") shall be
nominated by members of management of the Corporation provided that so long as
Gregory B. Maffei (the "Executive") is employed as chief executive officer of
the Corporation, three of such nominees shall be nominated by the Executive,
subject to reasonable approval of the majority of the then members of the board,
and the balance of such nominees shall be nominated by WFH.

          (h) At each meeting of Shareholders at which the election of members
of the Board is on the agenda, the Corporation shall recommend to Shareholders
the election of the Nominees as directors.

          3.2   Vacancies; Removal.

          (a) Subject to paragraph (b) of this Section 3.2, each director of the
Corporation shall hold office until his or her death or resignation or until his
or her successor shall have been duly elected and qualified. If any Investor
Nominee shall cease to serve as a director of the Corporation for any reason,
the vacancy resulting thereby shall be filled by another director nominated by
the Investor initially nominating that director.

          (b) Each Investor, shall have the right to call a meeting of
Shareholders to put forward a resolution of the Shareholders removing any
director designated by it, with or without cause, at any time.

          3.3    Quorum.

          (a) Subject to paragraphs (b) and (c) below, a quorum for meetings of
the Board shall be (i) in the case of notice of at least 48 hours before the
time fixed for the meeting, a majority of the directors then in office and (ii)
in the case of notice of at least

                                     - 5 -
<PAGE>

24 hours but less than 48 hours before the time fixed for the meeting, the
number of directors then in office less three (3).

          (b) If at a meeting of directors a quorum is not present, the
directors present at such meeting may adjourn the meeting to a fixed time and
place (provided they shall give written notice of such time and place to each
director not in attendance). At the meeting immediately following the adjourned
meeting, the directors present at such meeting shall constitute a quorum;
provided, however, that unless a full quorum is present as provided in paragraph
(a) above, the directors present at such meeting may not transact any business
except as specifically set forth in the notice of meeting.

          (c) The Corporation agrees that (i) each director shall be provided
written notice of the meetings of the Board , including adjourned meetings, at
least twenty-four (24) hours before such meetings, unless such notice is waived
in any manner, with attendance at such meetings constituting valid waiver (other
than attendance for the express purpose of objecting to the manner in which the
meeting was called), and (ii) each director shall be provided with an
opportunity to participate in each meeting of the Board by means of a conference
telephone or similar communications equipment.

          3.4    Directors' Indemnification.

          (a) The Corporation shall obtain and cause to be maintained in effect,
with financially sound insurers, a policy of directors' and officers' liability
insurance in an amount of at least US$5,000,000 or more and upon such terms as
are reasonably acceptable to the Investors.

          (b) The Memorandum of Association and Articles of Association or both,
shall to the fullest extent permitted by law provide for indemnification of, and
advancement of expenses to, and limitation of the personal liability of, the
directors of the Corporation or such other person or persons, if any, who,
pursuant to a provision of such Articles of Incorporation, exercise or perform
any of the powers or duties otherwise conferred or imposed upon such directors,
which provisions shall not be amended, repealed or otherwise modified in any
manner adverse to the directors until at least six (6) years following the date
that the Investors are no longer entitled to designate directors pursuant to
this Section 3.

          3.5 No Expansion of Duties. The parties acknowledge that the Financial
Investors, their Investor Affiliates and Canadian National Railway Company
("CN") and CN's Affiliates have investments in other business similar to and
which may compete with the Corporation's businesses ("Competing Businesses") and
reserve the right to make additional investments in other Competing Businesses
independent of their investments in the Corporation. By virtue of a Financial
Investor or CN holding Shares

                                     - 6 -
<PAGE>

or by having persons designated by or affiliated with such person serving on the
Board or any Subsidiary's Board of Directors (or the functional equivalent
thereof in the case of non-corporate Subsidiaries) or otherwise, no Financial
Investor, any of the Investor Affiliates, CN nor CN's Affiliates shall have any
obligation to the Corporation, any Subsidiary or any holder of Shares to refrain
from competing with the Corporation or any Subsidiary, making investments in
Competing Businesses, otherwise engaging in any commercial activity, and none of
the Corporation, any Subsidiary or any holder of Shares (other than such person)
shall have any right with respect to any such investments or activities
undertaken by such Financial Investor or CN. Without limitation of the
foregoing, each Financial Investor, any Investor Affiliates, CN or CN's
Affiliates may engage in or possess an interest in other business ventures of
any nature or description, independently or with others, similar or dissimilar
to the business of the Corporation or any Subsidiary, and none of the
Corporation, any Subsidiary or any holder of Shares (other than the person)
shall have any rights or expectancy by virtue of such person's relationships
with the Corporation, any Subsidiary, this Agreement or otherwise in and to such
independent ventures or the income of profits derived therefrom; and the pursuit
of any such venture, even if such investment is in a Competing Business, shall
not be deemed wrongful or improper. No Financial Investor, any Investor
Affiliates, CN nor CN's Affiliates shall be obligated to present any particular
investment opportunity to the Corporation or any Subsidiary even if such
opportunity is of a character that, if presented to the Corporation or a
Subsidiary, could be taken by the Corporation or such Subsidiary, and the
Financial Investor, their Investor Affiliates, CN or CN's Affiliates shall
continue to have the right to take for their own respective account or to
recommend to others any such particular investment opportunity.

          3.6 Expenses. The Corporation shall pay all reasonable travel expenses
and other out-of-pocket disbursements incurred by the directors to attend
meetings of the Board, of any Subsidiary board of directors or of any committees
thereof.

          3.7 Appointment of Senior Officers. The Board shall have the sole and
absolute authority to elect, appoint or hire any Senior Officer of the
Corporation.

          3.8 Shareholder Voting Arrangement. Each Shareholder, other than DLJ
and the GSCP Parties, agrees to vote all Voting Shares of the Corporation
beneficially owned by it with respect to the election or removal, to or from the
Board, of (a) so long as Providence has the right to nominate a Providence
Nominee in accordance with Section 3.1(e), the Providence Nominee in accordance
with the directions of Providence, (b) so long as Tyco has the right to nominate
a Tyco Nominee in accordance with Section 3.1(f), the Tyco Nominee in accordance
with the directions of Tyco, and (c) the Non-Investor Nominees in accordance
with the directions of the Person or Persons entitled to nominate such Nominees
in accordance with Section 3.1(g).

                                     - 7 -
<PAGE>

          SECTION 4. Representations and Warranties

          (a) Each of the parties hereto represents and warrants to the other
parties hereto as follows:

              (i) It has full power and authority to execute, deliver and
perform its obligations under this Agreement;

              (ii) This Agreement has been duly and validly authorized, executed
and delivered by it, and constitutes a valid and binding obligation of it,
enforceable against it in accordance with its terms except to the extent that
enforceability may be limited by bankruptcy, insolvency or other similar laws
affecting creditors' rights generally;

              (iii) The execution, delivery and performance of this Agreement by
it does not (A) violate, conflict with, or constitute a breach of or default
under its organizational documents, if any, or any material agreement to which
it is a party or by which it is bound or (B) violate any law, regulation, order,
writ, judgment, injunction or decree applicable to it;

              (iv) No consent or approval of, or filing with, any governmental
or regulatory body is required to be obtained or made by it in connection with
the transactions contemplated hereby (except those which have been made or
obtained); and

              (v) It is not a party to any contract or agreement which is
inconsistent with the rights of any party hereunder or otherwise conflicts with
the provisions hereof.

          (b) The Corporation represents and warrants to each of the Investors
and the Investor Affiliates as follows:

              (i) The disclosure contained in the Corporation's prospectus dated
April 19, 2000 under the captions "Description of Our Capital Stock",
"Capitalization", and "Description of Capital Stock and Share Capital
Reorganization" are true and complete in all material respects;

              (ii) the transactions contemplated by the Ledcor Roll-up Agreement
(as defined in the Prior Shareholders Agreement) have occurred in accordance
with its terms; and

              (iii) the Minority Roll-Up Transactions (as defined in the Prior
Shareholders Agreement) have each occurred or will occur immediately prior to
the

                                     - 8 -
<PAGE>

closing of the Public Equity Offering in accordance with the Minority Roll-Up
Agreements (or other transactions or series of transactions with similar
effect).

          (c) Ledcor represents and warrants to each of the parties hereto that
Ledcor did not breach Section 12.16 of the Prior Shareholders Agreement.

          SECTION 5. Certain Covenants.

          5.1 Protection of Investors. The Corporation and the Shareholders each
agree that all of the following provisions of this Section 5 are for the
exclusive benefit, protection and enjoyment of each of the Investors (severally
and not jointly) and their permitted successors and assigns, and may only be
enforced or remedied by the Investors (severally and not jointly) and their
permitted successors and assigns.

          5.2 System of Accounting. The books of account and other financial and
corporate records of the Corporation and its Subsidiaries shall be maintained in
accordance with good business and accounting practices and the financial
condition of the Corporation shall be accurately reflected in the financial
statements referred to in this Section.

          5.3 Compliance with Laws. The Corporation shall, and shall cause each
of its Subsidiaries to, comply with all applicable laws, rules regulations and
orders except where failure to comply would not have a material adverse effect.

          5.4 Insurance. The Corporation shall, and shall cause each of its
Subsidiaries to, keep its assets and those of its Subsidiaries which are of an
insurable character, if any, insured by financially sound and reputable insurers
against loss or damage by fire, extended coverage and other hazards and risks
and liability to Persons and property to the extent and in the manner customary
for companies in similar businesses similarly situated.

          5.5 Licenses and Permits. The Corporation shall, and shall cause each
of its Subsidiaries to, use its best efforts to obtain all Canadian and
non-Canadian federal, provincial, state and local governmental licenses,
permits, authorizations, consents, waivers, certificates and approvals material
to and necessary in the conduct of their business, including the Hibernia
Project.

          5.6 Disclosure of Investment. The Corporation, on the one hand, and
each of the Investors, on the other hand, agrees that it will not use in
advertising or publicity the name of any party hereto, or any partner or
employee of such party hereto or any of its respective affiliates, or any trade
name, trademark, trade device, service mark, symbol or any abbreviation,
contraction or simulation thereof owned by the other party hereto or any of its
respective affiliates, in either case without the prior written consent of

                                     - 9 -
<PAGE>

such party (except as such release or announcement may be required by applicable
securities law or the rules or regulations of the United States Securities and
Exchange Commission, in which case the party required to make the release or
announcement shall make reasonable best efforts to allow each other party
reasonable time to comment on such release or announcement in advance of such
issuance). From and after the date hereof, neither the Corporation nor any of
its Subsidiaries will represent, directly or indirectly, that any product or any
service provided by the Corporation has been approved or endorsed by any
Investor without the prior written consent of all of the Investors. The
Corporation and each of the Investors further agree that, from the date hereof
through the Closing Date, no public release or announcement concerning the
transactions contemplated hereby shall be issued by any party without the prior
consent of the Corporation and each Investor (which consent shall not be
unreasonably withheld), except as such release or announcement may be required
by applicable securities law or the rules or regulations of the United States
Securities and Exchange Commission, in which case the party required to make the
release or announcement shall make reasonable best efforts to allow each other
party reasonable time to comment on such release or announcement in advance of
such issuance.

          SECTION 6. Confidentiality.

          (a) The Investors and each of the other Shareholders severally (the
"Confidants") recognize that certain non-public, confidential, proprietary
information ("Confidential Information") may be furnished orally or in writing
to the Confidants by, or at the direction of, the Corporation. The Confidants
agree not to disclose any Confidential Information to any Person except to a
Person who is advised of the Confidant's obligations under this Section 6 and
who is (i) a partner, managing director, director, officer or employee of a
Confidant or a Confidant's Affiliate who is involved in the Confidant's
investment in the Corporation, who is consulted with respect to such investment,
or who a Confidant determines otherwise needs to know such information, or (ii)
a Person acting as an advisor to a Confidant in connection with such investment,
except with the consent of the Corporation or pursuant to a subpoena, civil
investigative demand (or similar process), order, statute, rule or other legal
requirement promulgated or imposed by a court or by a judicial, regulatory,
self-regulatory or legislative body, organization, agency or committee or
otherwise in connection with any judicial or administrative proceeding
(including, in response to oral questions, interrogatories or requests for
information or documents) in which a Confidant or Investor Affiliate is
involved. The Confidants acknowledge that the United States securities laws
prohibit any person who is in possession of material, non-public information
regarding an issuer from purchasing or selling securities of such issuer or from
communicating such information to any other person under circumstances in which
it is reasonably foreseeable that such person is likely to purchase or sell such
securities.

                                     - 10 -
<PAGE>

          (b) If Confidential Information is to be disclosed pursuant to the
foregoing paragraph, the Confidant will, to the extent practicable, promptly
notify the Corporation thereof and cooperate with the Corporation to the extent
legally permissible if it should seek to obtain an order or other reliable
assurance that confidential treatment will be accorded to designated portions of
the Confidential Information. The Confidants shall be entitled to periodic
reimbursement from the Corporation for expenses incurred by it or any Investor
Affiliate, including the fees and expenses of counsel, in connection with any
action taken pursuant to this paragraph.

          (c) Information will not be deemed Confidential Information if it (i)
was already available to, or in the possession of, the Confidant prior to its
disclosure by, or at the direction of, the Corporation, (ii) is or becomes
available in the public domain on or after the date hereof (other than as a
result of a disclosure by any Confidant or any of its advisors), or (iii) is
acquired from a person who is not known by a Confidant to be in breach of an
obligation of confidentiality to the Corporation.

          SECTION 7. Specific Performance; Injunction.

          (a) The parties agree that it is impossible to determine the monetary
damages which would accrue to the Corporation or any Shareholder or his personal
representative by reason of the failure of any Other Shareholder or the
Corporation to perform any of his or its obligations under this Agreement
requiring the performance of an act other than the payment of money only. Each
Shareholder shall be entitled to enforce its rights under this Agreement
specifically and to exercise all other rights existing in their favor. The
parties hereto agree and acknowledge that money damages may not be an adequate
remedy for any breach of the provisions of this Agreement and that each party
may in its sole discretion apply to any court of law or equity of competent
jurisdiction for specific performance and/or injunctive relief (without posting
a bond or other security) in order to enforce or prevent any violation of the
provisions of this Agreement.

          (b) In the event of a breach or threatened breach by a Shareholder of
any of the provisions of this Agreement, the Corporation, and the remaining
Shareholders shall be entitled to an injunction restraining such Shareholder
from any such breach. The availability of these remedies shall not prohibit the
Corporation from pursuing any other remedies for such breach or threatened
breach, including the recovery of damages from the Shareholder.

          SECTION 8. No Inconsistent Agreements. Neither the Corporation nor any
Shareholder shall take any action or enter into any agreement which is
inconsistent with the rights of any party hereunder or otherwise conflicts with
the provisions hereof.

                                     - 11 -
<PAGE>

          SECTION 9. Further Assurances. At any time or from time to time after
the date hereof, the parties agree to cooperate with each other, and at the
request of any other party, to execute and deliver any further instruments or
documents and to take all such further action as the other party may reasonably
request in order to evidence or effectuate the consummation of the transactions
contemplated hereby and to otherwise carry out the intent of the parties
hereunder.

          SECTION 10. Contractual Management Rights. The Corporation and each of
the Shareholders acknowledge that the provisions of this Agreement are intended,
among other things, to provide DLJ, GSCP and Providence with "contractual
management rights" within the meaning of the Employee Retirement Income Security
Act of 1974, as amended, and the regulations promulgated thereunder.

          SECTION 11. Severability. Whenever possible, each provision of this
Agreement shall be interpreted in such manner as to be effective and valid, but
if any provision of this Agreement is held to be invalid or unenforceable in any
respect, such invalidity or unenforceability shall not render invalid or
unenforceable any other provision of this Agreement. In the event that pursuant
to any regulatory authority or regulation, the Corporation is required to make
any revisions or modifications to any provision of this Agreement or any of the
other Documents, the parties agree to enter into good faith negotiations and
make revisions or modifications, to the extent possible, that are in compliance
with such regulation or the rules of such regulatory authority, and which are
designed to accomplish the purposes of such provision to be revised or modified.

          SECTION 12. Governing Law; Waiver of Jury Trial. This Agreement shall
be governed by and construed in accordance with the laws of the State of New
York without giving effect to the principles of conflicts of law, except for the
provisions of Section 3, which shall be governed by and construed in accordance
with the laws of the Province of British Columbia and the federal law of Canada.
Each of the parties hereto hereby irrevocably and unconditionally consents to
submit to the exclusive jurisdiction of the courts of the State of New York and
of the United States of America, in each case located in the County of New York,
for any action, proceeding or investigation in any court or before any
governmental authority ("Litigation") arising out of or relating to this
Agreement and the transactions contemplated hereby (and agrees not to commence
any Litigation relating thereto except in such courts), and further agrees that
service of any process, summons, notice or document by facsimile or registered
mail to its respective address set forth in this Agreement shall be effective
service of process for any Litigation brought against it in any such court. Each
of the parties hereto hereby irrevocably and unconditionally waives any
objection to the laying of venue of any Litigation arising out of this Agreement
or the transactions contemplated hereby in the courts of the State of

                                     - 12 -
<PAGE>

New York and of the United States of America, in each case located in the County
of New York,, and hereby further irrevocably and unconditionally waives and
agrees not to plead or claim in any such court that any such Litigation brought
in any such court has been brought in an inconvenient forum. EACH OF THE PARTIES
IRREVOCABLY AND UNCONDITIONALLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY
APPLICABLE LAW, ANY AND ALL RIGHTS TO TRIAL BY JURY IN CONNECTION WITH ANY
LITIGATION ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE TRANSACTIONS
CONTEMPLATED HEREBY.

          SECTION 13. Condition to Effectiveness; Successors and Assigns. This
Agreement shall only become effective upon the public Sale of equity securities
of the Company pursuant to a final prospectus (for which a receipt or receipts
have been obtained) no later than May 15, 2000. Until this Agreement becomes
effective (or if this Agreement never becomes effective) the parties hereto
agree that the Prior Shareholders Agreement will remain in full force and effect
without amendment or modification. This Agreement shall inure to the benefit of
and shall be binding upon the parties hereto and their respective successors,
assigns, heirs and personal representatives. No Shareholder shall have the right
to assign its rights under Section 3 of this Agreement without the consent of
the Corporation and each other Investor. Upon any such assignment, such assignee
shall have and be able to exercise all rights of the assigning Shareholder. The
parties acknowledge that, subject to compliance with applicable securities laws,
each Investor may transfer and assign all or a part of its rights and
obligations under this Agreement (including, for the avoidance of doubt, under
Section 3) to one or more other partnerships, corporations, trusts or other
organizations which have been created by or are controlled by, control or are
under common control with such Investor or one or more of the then current
partners, members or other equity holders of such Investor (the "Investor
Affiliates"), without the consent of the Corporation or any other Shareholder.
In addition each transferee from WFH and Ledcor Limited Partnership pursuant to
Section 3(a)(ii) of the Prior Shareholder's Agreement may transfer and assign
all or a part of its rights and obligations under this Agreement (including, for
the avoidance of doubt, under Section 3) to one or more partnerships,
corporations, trusts or other organizations which have been created by or
controlled by, control or are under common control with such transferee or one
or more of the then current partners, members or other equity holders of such
transferee, without the consent of the Corporation or any Shareholder.
Notwithstanding the foregoing, neither the Corporation nor any Person controlled
by the Corporation shall be deemed to be an Investor Affiliate of any Investor
for purposes of this Agreement. Upon any such assignment, the assignee shall
have and be able to exercise all rights of the assigning Shareholder.

          SECTION 14. 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, nationally
recognized overnight

                                     - 13 -
<PAGE>

courier or first class registered or certified mail, return receipt requested,
postage prepaid, addressed to such party at the address set forth below or such
other address as may hereafter be designated in writing by such party to the
other parties:

          (a) if to the Corporation, to:

                   360networks Inc..
                   #1510-1066 West Hastings Street
                   Vancouver, British Columbia  V6E 3X1
                   Fax:  (604) 681-6822
                   Attention:  Secretary

                   with a copy to:

                   Farris, Vaughan, Wills & Murphy
                   2600 - 700 West Georgia Street
                   Vancouver, British Columbia  V7Y 1B3
                   Fax:  (604)  661-9349
                   Attention:  Cameron G. Belsher

                   and

                   Cahill Gordon & Reindel
                   Eighty Pine Street
                   New York, New York
                   U.S.A.  10005
                   Fax:  (212) 269-5420
                   Attention:  Roger Andrus

          (b) if to DLJ, to:

                   DWF SRL
                   Chancery House
                   High Street
                   Bridgetown, Barbados, West Indies

                   and

                   DWF SRL
                   c/o DLJ Merchant Banking Partners II, L.P.
                   277 Park Avenue
                   New York, New York  10172

                                     - 14 -
<PAGE>

                   Fax:  (212) 892-7272
                   Attention:  Andrew Rush

                   with a copy to:

                   Latham & Watkins
                   885 Third Avenue, Suite 1000
                   New York, New York 10022-4802
                   Fax:  (212) 751-4864
                   Attention:  Steven Della Rocca

          (c) if to any of the GSCP Parties, to:

                   c/o Ernst & Young Services Ltd.
                   P.O. Box 261
                   Bay Street
                   Bridgetown,
                   Barbados, West Indies
                   Fax:  (246) 426-9551
                   Attention:  Carol-Ann Smith

                   and

                   c/o GS Capital Partners III, L.P.
                   85 Broad Street
                   New York, New York  10004
                   Fax:  (212) 902-3000
                   Attention:  Robert R. Gheewalla

                   with a copy to:

                   Fried, Frank, Harris, Shriver & Jacobson
                   One New York Plaza
                   New York, New York  10004
                   Fax:  (212) 859-4000
                   Attention:  Stuart Z. Katz

                   and

                   GS Capital Partners III, L.P.
                   85 Broad Street
                   New York, New York  10004

                                     - 15 -
<PAGE>

                   Fax:  (212) 357-5505
                   Attention:  Ben Adler

          (d) if to Providence, to:

                   Providence Equity Fiber, L.P.
                   50 Kennedy Plaza
                   Providence, Rhode Island  02903
                   Fax:  (401) 751-1790
                   Attention:  Glenn M. Creamer

                   with a copy to:

                   Edwards & Angell, LLP
                   2800 BankBoston Plaza
                   Providence, Rhode Island  02903
                   Fax:  (401) 276-6602
                   Attention:  David K. Duffell

          (e) if to Tyco, to:

                   Tyco Group S.A.R.L.
                   2nd Floor
                   6, Avenue Emile Reuter
                   L-2420 Luxembourg
                   Fax:  352-464-350
                   Attention:  Managing Director

                   with a copy to:

                   Tyco Submarine System Ltd.
                   250 Industrial Way West
                   Eatontown, New Jersey  07724
                   Fax:  (732) 578-7803
                   Attention:  General Counsel

          (f) if to WFH, to:

                   Worldwide Fiber Holdings Ltd.
                   1000-1066 West Hastings Street
                   Vancouver, British Columbia  V6E 3X1
                   Fax:  (604) 681-6822
                   Attention:  Chief Financial Officer

                                     - 16 -
<PAGE>

                   with a copy to:

                   McLennan Ross
                   600 West Chambers
                   12220 Stony Plain Road
                   Edmonton, Alberta  T5N 3Y4
                   Fax:  (780) 482-9102
                   Attention:  Rodney R. Neys

          (g) if to Ledcor, to:

                   Ledcor Inc.
                   1000-1066 West Hastings Street
                   Vancouver, British Columbia  V6E 3X1
                   Fax:  (604) 681-6650
                   Attention:  David Lede

                   with a copy to:

                   McLennan Ross
                   600 West Chambers
                   12220 Stony Plain Road
                   Edmonton, Alberta  T5N 3Y4
                   Fax:  (780) 482-9102
                   Attention:  Rodney R. Neys

          (h) if to any other Shareholder, to the notice information set forth
in Schedule I hereto.

All such notices, requests, consents and other communications shall be deemed to
have been given when received.

          SECTION 15. Amendments. Unless otherwise set forth in this Agreement,
the terms and provisions of this Agreement may be modified or amended, or any of
the provisions hereof waived, temporarily or permanently, pursuant to the
written consent of the parties hereto.

          SECTION 16. 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.

          SECTION 17. Nouns and Pronouns. Whenever the context requires, any
pronouns used herein shall include the corresponding masculine, feminine or
neuter

                                     - 17 -
<PAGE>

forms, and the singular form of names and pronouns shall include the plural and
vice-versa.

          SECTION 18. Entire Agreement. This Agreement and the other writings
referred to herein or delivered pursuant hereto which form a part hereof 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.

          SECTION 19. Counterparts. This Agreement may be executed in any number
of counterparts, and each such counterpart shall be deemed to be an original
instrument, but all such counterparts together shall constitute but one
agreement.

          SECTION 20. No Partnership. The obligations of each of the parties to
this Agreement are several and not joint. Nothing in this Agreement shall imply
or be deemed to imply a partnership, joint venture or other relationship between
the parties.

          SECTION 21. Ledcor Assurances. On the date hereof, Ledcor is a direct
party to this Agreement for purposes of Sections 1, 4(c) and 6 through 21
(inclusive). Ledcor is also a direct party to this Agreement as a Shareholder
(as such) only if and so long as (whether now or at any time or from time to
time hereafter) it is a holder of Shares. Furthermore, Ledcor agrees to take all
action necessary to cause WFH or any other Affiliates of Ledcor (with the
exception of the Corporation and its Subsidiaries) to fully perform their
respective obligations under this Agreement.

                                     - 18 -
<PAGE>

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

                                 360NETWORKS INC

                                 By: Signed
                                     ------------------------------------------
                                     Name:
                                     Title:

                                 DWF SRL

                                 By: Signed
                                     ------------------------------------------
                                     Name:
                                     Title:

                                 THE GSCP PARTIES:

                                 GS CAPITAL PARTNERS III, L.P.

                                 By: GS Advisors III, L.P., its general partner
                                 By: GS Advisors III, L.L.C., its general
                                     partner

                                 By: Signed
                                     ------------------------------------------
                                     Name:
                                     Title:

                                 GSCP3 WWF (Barbados) SRL

                                 By: Signed
                                     ------------------------------------------
                                     Name:
                                     Title:

                                 WWF (Barbados) SRL

                                 By: Signed
                                     ------------------------------------------
                                     Name:
                                     Title:

                                     - 19 -
<PAGE>

                                 PROVIDENCE EQUITY FIBER, L.P.

                                 By: Providence Equity Partners III L.P.
                                     its general partner,

                                 By: Providence Equity Partners III
                                     L.L.C.its general partner

                                 By: Signed
                                     -----------------------------------
                                     Name: Glenn M. Creamer
                                     Title:  Member and Managing
                                             Director

                                 TYCO GROUP S.A.R.L.

                                 By: Signed
                                     -----------------------------------
                                     Name:
                                     Title:

                                 WORLDWIDE FIBER HOLDINGS LTD.

                                 By: Signed
                                     -----------------------------------
                                     Name:
                                     Title:

                                 LEDCOR INC.

                                 By: Signed
                                     -----------------------------------
                                     Name:
                                     Title:

                                 CANADIAN NATIONAL RAILWAY
                                 COMPANY.

                                 By: Signed
                                     -----------------------------------
                                     Name:
                                     Title:

                                     - 20 -
<PAGE>

                                 Signed
                                 ----------------------------------------------
                                 CLIFFORD LEDE

                                 Signed
                                 ----------------------------------------------
                                 DAVID LEDE

                                 Signed
                                 ----------------------------------------------
                                 GREGORY B. MAFFEI

                                 Signed
                                 ----------------------------------------------
                                 LARRY OLSEN

                                 Signed
                                 ----------------------------------------------
                                 WILLIAM RAMSEY

                                 Signed
                                 ----------------------------------------------
                                 RON STEVENSON

                                 Signed
                                 ----------------------------------------------
                                 STEPHEN STOW

                                 Signed
                                 ----------------------------------------------
                                 JIM VOELKER

                                 MADISON SQUARE INC.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                     - 21 -
<PAGE>

                                 LEDCOR INDUSTRIES LIMITED

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 LEDCOR INDUSTRIES LIMITED
                                 as General partner for Ledcor Partnership

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 MACKENZIE PARTNERS, LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                     - 22 -
<PAGE>

                                 LIBERTY WF HOLDINGS LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 COMCAST TSIX HOLDINGS, INC.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 OAK INVESTMENTS PARTNERS IX, L.P.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 KLEINER PERKINS CAUFIELD & BYERS

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 InterNAP NETWORK SERVICES CORPORATION

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 NATHAN MYHRVOLD

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 divine interVentures, inc.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                     - 23 -
<PAGE>

                                 GT GROUP TELECOM SERVICES CORP.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 MSD SELECT SPONSORS VENTURES I, LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 DBV INVESTMENTS, LP

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 MSD EC I, LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 BAYCLIFFE LIMITED

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 594745 B.C. LTD.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 MACKENZIE PARTNERS II LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                     - 24 -
<PAGE>

                                 NEWS AMERICA INCORPORATED

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                     - 25 -
<PAGE>

                                 URBANLINK HOLDINGS LTD.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 RAMSEY BEIRNE INVESTMENT
                                 PARTNERS, LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 MI-TECH COMMUNICATIONS, LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                     - 26 -

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00026-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00026-of-00352.parquet"}]]