Document:

<PAGE>   1
                                                            Exhibit 10.1

                                   5 MAY 2000

                         REUTERS OVERSEAS HOLDINGS B.V.

                                 REUTERS LIMITED

                          AETHER EUROPEAN HOLDINGS B.V.

                              AETHER SYSTEMS, INC.

                           SILA COMMUNICATIONS LIMITED

                        ================================

                             SHAREHOLDERS AGREEMENT
                                   RELATING TO
                           SILA COMMUNICATIONS LIMITED

                        ================================

<PAGE>   2

                                    CONTENTS

<TABLE>
<CAPTION>
CLAUSE                                                                      PAGE
<S>                                                                         <C>

1.   INTERPRETATION............................................................1

      Definitions..............................................................1
      Headings.................................................................7
      Agreed Form..............................................................7
      Exercise of powers of control............................................7

2.   PURPOSE OF THE COMPANY AND ITS GROUP......................................7

      Business.................................................................7

3.   CAPITAL AND FURTHER FINANCE...............................................7

      Issue of new shares......................................................7
      Funding support by the principals........................................9
      Termination..............................................................9

4.   DIRECTORS AND MANAGEMENT..................................................9

      Supervision by the Board.................................................9
      Board of Directors.......................................................9
      Chairman of the Board...................................................10
      Appointment and Removal of Directors....................................10
      Quorum..................................................................10
      Notice and Agenda.......................................................11
      Board voting............................................................11
      Board Committee.........................................................11
      Executive Officers; Employee Arrangements...............................11
      Employee Share Options..................................................12

5.   RESERVED MATTERS.........................................................12

      Reserved Shareholder Matters............................................12
      Reserved Board Matters..................................................12
      Method of approval by Shareholders......................................13
      Meetings of Shareholders................................................13
      Termination.............................................................13

6.   FINANCIAL MATTERS........................................................13

      Accounting Principles...................................................13
      Auditors................................................................14
      Financial Year..........................................................14

7.   INFORMATION AND REPORTING................................................14

      Inspection and information..............................................14
</TABLE>

<PAGE>   3

<TABLE>
<S>                                                                         <C>
      Accounts, Business Plan and Budgets.....................................14

8.   CONFIDENTIALITY..........................................................15

      Confidentiality obligation..............................................15
      Exceptions from confidentiality obligation..............................16
      Employees, agents and advisers..........................................17
      Return of Confidential Information......................................17
      Survival after termination..............................................17

9.   REGULATORY MATTERS.......................................................18

      Co-operation............................................................18

10.  POST CLOSING MATTERS.....................................................18

      Claims by the Company...................................................18
      Tax Matters.............................................................18
      Surrender of and payment for relief.....................................18
      Stamp duty..............................................................19

11.  TRANSFER OF SECURITIES...................................................20

      General.................................................................20
      Restriction on transfer.................................................20
      Initial period..........................................................21
      Transfer Notice.........................................................21
      Right of Relevant Principals to purchase or tag along...................22
      Company's right to buy Seller's Securities..............................23
      Purchase of Seller's Securities.........................................23
      Right to Tag Along......................................................24
      Seller's right to sell to Third Party Purchaser.........................25
      Sale terms..............................................................25
      Intra-Group transfers...................................................26
      Shareholder ceasing to be a Subsidiary..................................27
      Obligations of Transferee...............................................27

12.  INSOLVENCY AND DEFAULT...................................................27

      Default Events..........................................................27
      Right to make offer.....................................................28
      Offer notice............................................................28
      Reference to Expert.....................................................29
      Right to purchase at Fair Price.........................................29
      Completion..............................................................30
      Transfer terms..........................................................30

13.  DEFAULT..................................................................31

14.  FURTHER ASSURANCES.......................................................31

      Exercise of rights and powers...........................................31
      Performance by Subsidiaries.............................................31
</TABLE>

                                                                         Page II
<PAGE>   4

<TABLE>
<S>                                                                         <C>
15.  NON-ASSIGNMENT...........................................................32

16.  WAIVER OF RIGHTS.........................................................33

17.  AMENDMENTS...............................................................33

18.  INVALIDITY...............................................................33

19.  NO PARTNERSHIP OR AGENCY.................................................33

20.  ANNOUNCEMENTS............................................................33

21.  COSTS....................................................................34

22.  ENTIRE AGREEMENT.........................................................34

23.  CONFLICT WITH ARTICLES...................................................34

      Supremacy of this Agreement.............................................34
      Transfers of Shares.....................................................35
      Appointment and Removal of Directors....................................35

24.  TERMINATION OF AGREEMENT.................................................35

      Duration................................................................35

25.  SILA TRADE MARK..........................................................36

26.  NOTICES..................................................................37

      Address of notices......................................................37
      English language........................................................39

27.  SETTLEMENT OF DISPUTES...................................................39

      Arbitration.............................................................40

28.  COUNTERPARTS.............................................................40

29.  NO RIGHTS UNDER CONTRACTS (RIGHTS OF THIRD PARTIES) ACT 1999.............40

30.  GOVERNING LAW............................................................40

SCHEDULE 1....................................................................43

      Part 1..................................................................43
      Reserved Shareholder Matters............................................43
      Part 2..................................................................44
      Reserved Board Matters..................................................44
</TABLE>

                                                                        Page III
<PAGE>   5

<TABLE>
<S>                                                                         <C>
SCHEDULE 2....................................................................46

      Deed of Adherence.......................................................46

SCHEDULE 3....................................................................50

      Accounting Principles...................................................50

SCHEDULE 4....................................................................54

      Memorandum and Articles of the Company..................................54
</TABLE>

                                                                         Page IV
<PAGE>   6

THIS AGREEMENT is made on 8 May 2000

BETWEEN:

(1)    REUTERS OVERSEAS HOLDINGS B.V., whose seat is at Amsterdam, The
       Netherlands and office is at Amsterdam, The Netherlands, Drentestraat
       (REUTERS);

(2)    AETHER EUROPEAN HOLDINGS B.V., whose seat is at Rotterdam, The
       Netherlands and office is at Aert van Nesstraat 45, 3012CA Rotterdam
       (AETHER);

(3)    SILA COMMUNICATIONS LIMITED, whose registered office is at 4 Carlton
       Gardens, Pall Mall, London SW1Y 5AA (the COMPANY);

(4)    REUTERS LIMITED, whose registered office is at 85 Fleet Street, London
       EC4P 4AJ (REUTERS PARENT);

(5)    AETHER SYSTEMS, INC., whose principal place of business is at 11460
       Cronridge Drive, Owings Mills, MD 21117, USA (AETHER PARENT).

WHEREAS:

(A)    Reuters Parent, Aether Parent and the Company have entered into the
Master Contribution Agreement pursuant to which they agreed to form the Company
for the purpose of carrying on the Business throughout the Territory (as such
terms are defined below).

(B)    Reuters and Aether are entering into this Agreement to set out the terms
governing their relationship as shareholders in the Company.

(C)    Reuters Parent and Aether Parent are entering into this Agreement to
ensure that their respective Subsidiaries carry out certain obligations under
this Agreement.

IT IS AGREED as follows:

INTERPRETATION

DEFINITIONS

1.1    In this Agreement:

ACCOUNTING PRINCIPLES means the accounting principles and policies (to be
consistent with generally accepted accounting principles in the UK) to be
adopted by the Company as set out in Schedule 3;

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AETHER DIRECTORS means the Directors which are appointed by Aether from time to
time;

AETHER GROUP means Aether Parent, Aether and their Affiliates from time to time
provided that for the purposes of calculating Aether's Shareholding Proportion
or Tag-Along Proportion, neither the Company nor any Subsidiary of the Company
shall be regarded as an Affiliate of Aether or Aether Parent or a member of
Aether Group or a Subsidiary of Aether or any other Aether Group Member;

AETHER GROUP MEMBER means any member of the Aether Group;

AFFILIATE means, in relation to a principal, any entity of which that principal
is a Subsidiary and any other entity which is a Subsidiary of such entity, from
time to time;

ANCILLARY AGREEMENTS means the agreements referred to in Schedule 3 to the
Master Contribution Agreement;

ARTICLES means the Company's Articles of Association in the agreed form, which
is attached hereto as Schedule 4, as amended from time to time;

B SHARES means B Shares of 5 pence each in the capital of the Company having the
rights and privileges set out in the Articles;

BOARD means the Company's board of directors or any duly appointed committee of
it to the extent that such committee is authorised to take the relevant action;

BUDGET means a budget for the Company's Group for a particular Financial Year in
a format approved from time to time by the Board;

BUSINESS means the development, production and marketing of wireless services,
applications and solutions for enterprises, professionals and consumers
throughout the Territory;

BUSINESS DAY means a day (other than a Saturday or Sunday) on which banks
generally are open in London for a full range of business;

BUSINESS PLAN means a rolling business plan for the Company and its Subsidiaries
relating to the then current Financial Year and the succeeding Financial Year
(in a format approved from time to time by the Board) to be updated annually;

CHAIRMAN means the chairman from time to time of the Board;

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CHIEF EXECUTIVE means the chief executive from time to time of the Company;

COMPANY includes any body corporate, wherever incorporated;

COMPANY'S GROUP means the Company and its Subsidiaries from time to time;

DEFAULT EVENT has the meaning given to that expression in clause 12;

DIRECTORS means the Company's directors;

EMPLOYEE SHARE OPTIONS means options over Ordinary Shares in the Company which
may be granted from time to time by the Company to its employees;

FAIR PRICE means the open market value of the relevant Shares between a willing
seller and a willing third party buyer at the date of the relevant Transfer
Notice with any premium or discount by reference to the percentage of the Shares
being sold or transferred;

FINANCIAL YEAR means a financial period of the Company (commencing, other than
in the case of its initial financial period, on 1 January and ending on 31
December);

FLOTATION means the admission of Ordinary Shares to listing or quotation, or the
giving effect to trading arrangements in relation to Shares, on any of the
London Stock Exchange, the New York Stock Exchange or the Nasdaq National Market
System or any other exchange in each case at the request of the Company, and the
related public offering of shares;

GROUP means, in relation to an entity other than Reuters, Aether or the Company,
that entity and its Affiliates from time to time and in relation to the Company,
the Company and its Subsidiaries from time to time;

INDIRECT SHAREHOLDING PROPORTION means, in relation to a principal's interest in
a Subsidiary of the Company, the indirect proportionate interest in the issued
share capital of such Subsidiary of the Company held from time to time by such
principal (to be determined as such principal's Shareholding Proportion of the
proportion which the aggregate shareholdings of the Company (and/or any of its
Subsidiaries which are Shareholders in the relevant Subsidiary) in the relevant
Subsidiary constitute of the entire issued share capital of such Subsidiary);

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INVESTMENT means (i) any acquisition, through merger, consolidation, purchase,
repurchase, redemption or otherwise, of any Person or of any securities (other
than a redemption or repurchase in accordance with the terms of the securities
re-purchased or redeemed) or assets of, or interest in, any Person or (ii) any
direct or indirect loan, advance or other extension of credit or capital
contribution to (by means of transfers of cash or other property to others or
payments for property or services for the account or use of others, or
otherwise), or purchase or acquisition of capital stock, bonds, notes,
debentures or other securities or evidence of debt issued by, any other Person;

MASTER CONTRIBUTION AGREEMENT means the contribution agreement between Reuters
Limited, Aether and the Company dated 5 May 2000;

MEMORANDUM means the Company's Memorandum of Association in the agreed form,
which is attached hereto as Schedule 4, as amended from time to time;

ORDINARY SHARES means Ordinary Shares of 5 pence (and the one Ordinary Share of
US$1) each in the capital of the Company having the rights and privileges set
out in the Articles;

PARTY or PARTIES means the principals and the Company;

PERSON means any individual, corporation, joint stock company, limited liability
company, partnership, firm, joint venture, trust, association, unincorporated
organisation, governmental or regulatory body or other entity;

PREFERENCE SHARES means Preference Shares of 5 pence each in the capital of the
Company having the rights and privileges set out in the Articles;

PRINCIPALS means Reuters, Aether and such other person as becomes a principal to
this Agreement by entering into a Deed of Adherence in accordance with the terms
hereof (and PRINCIPAL shall be construed accordingly), but does not include
Reuters Parent or Aether Parent;

RELEVANT PRINCIPAL means:

(a)    Reuters;

(b)    Aether; and

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(c)    any principal other than Reuters and Aether and which has a Shareholding
       Proportion of 20% or greater;

RELEVANT SECURITIES means shares of any class, stock, other securities (whether
debt or equity) convertible or exchangeable into such shares or stock, options
or warrants over such shares, stock or securities and derivatives referenced to
any of the foregoing;

RESERVED BOARD MATTERS means those matters set out in Part 2 of Schedule 1;

RESERVED SHAREHOLDER MATTERS means those matters set out in Part 1 of Schedule
1;

REUTERS DIRECTORS means the Directors which are appointed by Reuters from time
to time;

REUTERS GROUP means Reuters Parent, Reuters and their Affiliates, from time to
time, provided that for the purposes of calculating Reuters Shareholding
Proportion or Tag-Along Proportion, neither the Company nor any Subsidiary of
the Company shall be regarded as an Affiliate of Reuters or Reuters Parent or a
member of the Reuters Group or as a Subsidiary of Reuters or another Reuters
Group Member;

REUTERS GROUP MEMBER means any member of the Reuters Group from time to time;

SECURITY INTEREST means any mortgage, charge, pledge, right of usufruct, lien,
right of set-off, encumbrance or any security interest whatsoever, howsoever
created or arising (including any analogous security interest under local law);

SHAREHOLDERS means the holders from time to time of the Ordinary Shares and the
holders from time to time of the Preference Shares (and SHAREHOLDER shall be
construed accordingly);

SHAREHOLDING PROPORTION means in relation to a principal, the respective
proportion of the issued Ordinary Shares and Preference Shares (other than
Ordinary Shares issued pursuant to the exercise of options) taken together which
is held from time to time by the principal and members of its Group;

SHARES means issued Ordinary Shares and Preference Shares in the Company's
capital;

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SILA TRADE MARKS shall have the meaning given to that term in the Master
Contribution Agreement;

SUBSIDIARY means, in relation to an undertaking (the HOLDING UNDERTAKING), any
other undertaking in which the holding undertaking (or persons acting on its or
their behalf) for the time being directly or indirectly holds or controls both:

(a)    a majority of the voting rights exercisable at general meetings of the
       members of that undertaking on all, or substantially all, matters; and

(b)    the right to appoint or remove directors having a majority of the voting
       rights exercisable at meetings of the board of directors of that
       undertaking on all, or substantially all, matters,

and any undertaking which is a Subsidiary of another undertaking shall also be a
Subsidiary of any further undertaking of which that other is a Subsidiary but
excluding (i) with respect to Reuters and Reuters Parent, each of Dow Jones
Reuters Business Interactive LLC, TIBCO Software Inc, Instinet Corporation,
Reuters announced ventures with Equant N.V. and Multex.com, Inc. and any other
undertaking the day-to-day management of which is not in fact controlled by
Reuters and is designated in good faith by notice in writing to the other
parties from time to time by Reuters and each of the Subsidiaries of such
designated undertaking from time to time and (ii) with respect to Aether, any
undertakings the day-to-day management of which is not in fact controlled by
Aether and is designated in good faith by notice in writing to the other parties
from time to time by Aether and each of the Subsidiaries of such designated
undertaking from time to time; provided that any undertaking which is
transferred Shares directly or indirectly in accordance with clause 11.11 shall
remain or become a Subsidiary of Aether or Reuters (as the case may be) until it
ceases to hold such Shares;

TERRITORY means members of the European Union as at the date of this Agreement,
Norway, Liechtenstein, The Principality of Monaco, The Channel Islands,
Bulgaria, Hungary, Slovakia, Switzerland, The Czech Republic, countries which
were part of the former USSR or the former Yugoslavia, Malta, Romania, Poland,
Andorra, Albania, Turkey, Cyprus, Iceland and Greenland;

TRADE MARK LICENCE means the trade mark licence between Reuters Parent, Aether
Parent and the Company entered into on the same date as the Agreement;

                                                                          Page 6
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TRANSFER NOTICE has the meaning given to the expression in clause 11.4;

UNDERTAKING means a body corporate or partnership or an unincorporated
association carrying on trade or a business with or without a view to profit. In
relation to an undertaking which is not a company, expressions in this Agreement
appropriate to companies are to be construed as references to the corresponding
persons, officers, documents or organs (as the case may be) appropriate to
undertakings of that description.

HEADINGS

1.2    The headings in this Agreement do not affect its interpretation.

AGREED FORM

1.3    A reference to a document in this Agreement in the AGREED FORM is to a
document agreed among the parties and initialled by them or on their behalf for
identification purposes.

EXERCISE OF POWERS OF CONTROL

1.4    Where any obligation in this Agreement is expressed to be undertaken or
assumed by any party, that obligation is to be construed as requiring the party
concerned to exercise all rights and powers of control over the affairs of any
other person which that party is able to exercise (whether directly or
indirectly) in order to secure performance of the obligation.

PURPOSE OF THE COMPANY AND ITS GROUP

BUSINESS

2.     The business of the Company and its Group shall initially be to engage in
the Business throughout the Territory, without prejudice to the ability of the
Company and its Group to alter, reduce or expand the business of the Company's
Group after the date of this Agreement (in accordance with the other provisions
of this Agreement).

CAPITAL AND FURTHER FINANCE

ISSUE OF NEW SHARES

3.1    Subject to clause 5.1, the Company's issued share capital may be
increased from time to time but (unless Aether and Reuters agree otherwise) the
Company shall not issue any Relevant Securities unless such Relevant Securities
are offered for subscription to Aether and

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Reuters pro rata to their respective Shareholding Proportions as at the close of
business on the date prior to such offer.

3.2    The Company shall procure that no Subsidiary of the Company shall issue
any Relevant Securities (other than to the Company and its wholly-owned
Subsidiaries) unless such Relevant Securities are first offered for subscription
to Aether and Reuters pro rata to their respective Indirect Shareholding
Proportions in such Subsidiary as at the close of business on the date prior to
such offer.

3.3    At least twenty (20) days before the Company or any of its Subsidiaries
shall offer or issue any Relevant Securities, it shall first give Aether and
Reuters notice (a FUNDING NOTICE) of any proposed issue and each of Aether's and
Reuter's proportional entitlement calculated in accordance with clauses 3.1 and
3.2 and of the price and terms on which such Relevant Securities are to be
offered or issued. On receipt of the Funding Notice, Aether and Reuters shall
each have the right to subscribe for up to such number of Relevant Securities at
such price and on such terms by giving notice within twenty (20) days of
receiving the Funding Notice (the SUBSCRIPTION NOTICE). The Subscription Notice
shall state the number of Relevant Securities for which it wishes to subscribe
together with the number of additional Relevant Securities (if any) in excess of
its entitlement for which it wishes to subscribe.

3.4    If Aether and Reuters do not all accept the offer in respect of their
respective proportional entitlements in full, the Relevant Securities not so
accepted shall be used to satisfy any claims for additional Relevant Securities
under any Subscription Notice, and, if there are insufficient Relevant
Securities being issued, then such Relevant Securities shall be offered to each
principal making a claim for additional Relevant Securities pro rata to their
Shareholding Proportions, provided that neither Aether nor Reuters shall be
required to take more Relevant Securities than it shall have specified in its
Subscription Notice.

3.5    The provisions of clauses 3.1 to 3.4 shall not apply to an issue of
Relevant Securities by the Company (i) in connection with a Flotation with net
proceeds to the Company of at least pound sterling 15 million and a per share
price which implies a valuation of the fully diluted share capital of the
Company of at least pound sterling 187.5 million or (ii) as all or part of the
purchase price or other consideration paid by the Company in connection with any
acquisition of another business, subject to clauses 4.1 and 5.1 or (iii) in
connection with the issue of Shares in accordance with the Employee Share
Options.

                                                                          Page 8
<PAGE>   14

FUNDING SUPPORT BY THE PRINCIPALS

3.6    The parties intend that the Company and its Subsidiaries should be
self-financing and/or should be able to obtain additional funds from third
parties without the need for recourse to its Shareholders. No principal or its
Affiliates shall be obliged to (but nothing in this clause 3.6 shall prevent a
principal or its Affiliates from agreeing with the Company to) contribute
further funds or participate in any guarantee, bond or similar undertaking for
the benefit of the Company or any of its Subsidiaries.

TERMINATION

3.7    The provisions of this clause 3 (other than clause 3.6) shall be subject
to clause 25.2.

DIRECTORS AND MANAGEMENT

SUPERVISION BY THE BOARD

4.1    Subject to the requisite approval of those matters which are Reserved
Shareholder Matters or Reserved Board Matters in accordance with clause 5.1 and
clause 5.2 respectively, the Board shall be responsible for the overall
direction, and supervision and management of the Company's Group.

BOARD OF DIRECTORS

4.2    The Board shall comprise seven directors. The number of Directors which
Reuters and Aether shall be entitled to nominate (for appointment in accordance
with clause 4.6) will be according to the Shareholding Proportions of Reuters
and Aether as follows:

<TABLE>
<CAPTION>
   SHAREHOLDING PROPORTION                  NUMBER OF DIRECTORS
<S>                                         <C>

      >/= 50 per cent.                               4
      >/= 35 per cent.                               3
      >/= 25 per cent.                               2
      >/= 13 per cent.                               1
</TABLE>

4.3    Subject to clause 24.2, if either Reuters or Aether has a Shareholding
Proportion of at least 5% but less than 13% it shall have the right to nominate
one person to attend and observe, but not to vote, at any Board meeting.

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4.4    The initial Board appointments at Completion shall include:

<TABLE>
<CAPTION>
AETHER DIRECTORS                         REUTER DIRECTORS
<S>                                      <C>

David Oros                               Devin Wenig
Brian Keane                              Jeremy Penn
Bo Kroll                                 Jean-Claude Marchand
Carter Beese
</TABLE>

CHAIRMAN OF THE BOARD

4.5    David Oros shall be the initial chairman of the Board.

APPOINTMENT AND REMOVAL OF DIRECTORS

4.6    Each principal will (and will procure that any Shareholder in its Group
will) vote in favour of a proposal to appoint or remove a Director if the
principal who has the right to nominate or has nominated the Director concerned,
notifies the Company in writing (such notice signed by it or on its behalf) of
its proposal to nominate for appointment and nominate for dismissal
respectively. The Company shall procure that a general meeting of Shareholders
shall take place as soon as possible in accordance with the Articles following
receipt of such notice from the relevant principal. Any removal shall be without
prejudice to any claim which any removed Director may have under any contract
between him and the Company. A principal removing a Director shall indemnify the
Company for any liability arising from the removal.

QUORUM

4.7    The quorum for transacting business at any Board meeting (other than an
adjourned meeting) shall require to be present when the relevant business is
transacted:

(a)    at least one (1) Reuters Director at any time that Reuters is entitled to
       nominate at least two directors under clause 4.2; and

(b)    at least one (1) Aether Director at any time that Aether is entitled to
       nominate at least two directors under clause 4.2.

If that quorum is not present within thirty (30) minutes from the time when the
meeting should have begun or if during the meeting there is no longer a quorum,
the meeting shall be adjourned for two (2) Business Days. A Director shall be
regarded as present for the purposes of a quorum if represented by an alternate
Director in accordance with clause 4.9.

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NOTICE AND AGENDA

4.8    At least five (5) days written notice shall be given to each Board member
(and any part with rights under clause 4.3) of any Board meeting unless at least
one Reuters Director (or his alternate) and at least one Aether Director (or his
alternate) approve a shorter notice period. Any notice shall include an agenda
identifying in reasonable detail the matters to be discussed at the meeting
together with copies of any relevant papers to be discussed at the meeting. If
any matter is not identified in reasonable detail, the Board shall not decide
upon it, unless all Board members agree in writing.

BOARD VOTING

4.9    Subject to clauses 5.1 and 5.2, the Board shall decide on matters by
simple majority vote. Each Director shall have one vote. Any Director who is
absent from a meeting may authorise any other Director to act as his alternate
and to vote in his place at the meeting.

BOARD COMMITTEE

4.10   Subject to any restrictions under applicable law, regulation or stock
exchange custom or practice, for so long as Reuters has a Shareholding
Proportion of 25 per cent. or more, Reuters shall be entitled to be represented
on each committee by at least one Reuters Director provided that if Reuters
Shareholding Proportion is 17 per cent. or more a Director appointed by it shall
be entitled to be a member of one half of all committees or three committees
(whichever is the greater), but any such Director who fails to attend two
consecutive meetings of any relevant committee may (within two months after the
second such meeting) be removed from that committee. Subject to any restrictions
under applicable law, regulation or stock exchange custom or practice, for so
long as Aether has a Shareholding Proportion of 25 per cent. or more, Aether
shall be entitled to be represented on each committee by at least one Aether
Director provided that if Aether's Shareholding Proportion is between 17 per
cent. a Director appointed by it shall be entitled to be a member of one half of
all committees or three committees (whichever is the greater), but any such
Director who fails to attend two consecutive meetings of any relevant committee
may (within two months after the second such meeting) be removed from that
committee.

EXECUTIVE OFFICERS; EMPLOYEE ARRANGEMENTS

4.11   The principals will take all action necessary to cause the appointment
of the following individuals to the positions (or the delegation to such
individuals of the authorities customarily associated

                                                                         Page 11
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with such position) set out opposite their names, at the date of this Agreement,
without prejudice to the ability of the Board to take any action after the date
of this Agreement with respect to such persons and officers as they determine in
accordance with law and this Agreement:

<TABLE>
<CAPTION>
NAME                                        POSITION
<S>                                         <C>

David Oros                                  Chief Executive Officer
Bo Kroll                                    President
Jon Baile                                   Executive Vice President
</TABLE>

4.12   Subject to all applicable laws, with respect to existing or acquired
employees or otherwise, the principals shall procure that all existing and
future employees of the Company and its Subsidiaries shall be subject to
appropriate non-competition provisions, confidentiality agreements and
assignments of intellectual property rights.

EMPLOYEE SHARE OPTIONS

4.13   Employee Share Options may be granted as the Board sees fit to employees
of the Company and its Subsidiaries provided that the initial pool of such
Employee Share Options shall in aggregate relate to a number of Shares which
does not exceed 12% of the issued share capital of the Company at the date of
this Agreement (fully diluted to take account of such Employee Share Options).

RESERVED MATTERS

RESERVED SHAREHOLDER MATTERS

5.1    Reuters Parent, Aether Parent and the principals shall use their
respective powers to ensure that no action or decision relating to any of the
Reserved Shareholder Matters is taken (whether by the Board, the Company, any
Subsidiary of the Company or any of the directors, officers or employees of any
member of the Company's Group) without the prior approval of the holders of the
Ordinary Shares and Preference Shares carrying the right to exercise not less
than 75% of the voting rights in the Company in accordance with clause 5.3.

RESERVED BOARD MATTERS

5.2    The Reuters Parent, Aether Parent and the principals shall use their
respective powers to ensure that no action or decision relating to any of the
Reserved Board Matters is taken (whether by the Board, the Company, any
Subsidiary of the Company or any of the directors, officers or employees of any
member of the Company's Group) without

                                                                         Page 12
<PAGE>   18

the prior approval by resolution of the Board at a meeting at which at least
four (4) Directors vote in favour of the relevant matter.

METHOD OF APPROVAL BY SHAREHOLDERS

5.3    The principals shall give their approval to any of the Reserved
Shareholder Matters (or to any variation of them) either in writing by Reuters
and Aether or by their authorised representatives for this purpose or by
representatives of the Shareholders at a general meeting of the Company.

MEETINGS OF SHAREHOLDERS

5.4    General meetings of Shareholders shall take place in accordance with the
applicable provisions of the Articles on the basis that:

(a)    at least 10 days' notice shall be given to each Shareholder of any
       meeting;

(b)    the notice of meeting shall set out an agenda identifying in reasonable
       detail the matters to be discussed (unless the Shareholders agree
       otherwise);

(c)    the chairman of the meeting shall not have a casting vote;

(d)    a decision to approve any of the Reserved Shareholder Matters shall
       require approval in accordance with Clauses 5.1 and 5.3.

Any matters requiring a general meeting of or approval by the Shareholders under
relevant corporate laws, but not covered by the Reserved Shareholder Matters,
shall be dealt with in accordance with the Articles.

TERMINATION

5.5    The provisions of clauses 5.1 and 5.2 shall be subject to clause 25.2.

FINANCIAL MATTERS

ACCOUNTING PRINCIPLES

6.1    The Company shall adopt the Accounting Principles. The Company shall, if
Aether or Reuters is required to so provide under applicable law, applicable
rules of any stock exchange or trading market, or applicable accounting rules,
and as soon as practicable following a request by Aether or Reuters, provide the
principals with a

                                                                         Page 13
<PAGE>   19

reconciliation of the Company's financial statements to generally accepted
accounting principles in the United States.

AUDITORS

6.2    The principals shall use their respective powers to ensure that the
Company's initial auditors shall be KPMG.

FINANCIAL YEAR

6.3    The principals shall use their respective powers to ensure that the
Company's Financial Year shall end on 31 December in each year, unless the
principals agree otherwise.

INFORMATION AND REPORTING

INSPECTION AND INFORMATION

7.1    Subject to clause 7.3, each principal may, upon reasonable notice to the
Company, examine the separate books, records and accounts to be kept by the
Company and each of its Subsidiaries. Each principal shall be entitled to
receive all information, including monthly management accounts and operating
statistics and other trading and financial information, a principal reasonably
requires to keep it properly informed about the business and affairs of the
Company and generally to protect its interests as a Shareholder.

ACCOUNTS, BUSINESS PLAN AND BUDGETS

7.2    Without prejudice to the generality of clause 7.1, and subject to clause
7.3, the Company shall supply the principals with copies of:

(a)    audited annual accounts for the Company and each of its Subsidiaries
       (complying with all relevant legal requirements) and, if appropriate, the
       Company's Group audited consolidated annual accounts, within 4 months of
       the end of the relevant Financial Year;

(b)    a Business Plan and itemised revenue and capital Budgets for each
       Financial Year covering each principal division of the Company's Group
       and showing proposed trading and cash flow figures, manning levels and
       all material proposed acquisitions, disposals and other commitments for
       that Financial Year, no later than 3 months prior to the end of the
       previous Financial Year; and

(c)    unaudited monthly and quarterly management accounts of each principal
       division of the Company's Group; these shall include a consolidated
       profit and loss account, balance sheet and cash flow

                                                                         Page 14
<PAGE>   20

       statement broken down according to the principal divisions of the
       Company's Group including a statement of progress against the relevant
       Business Plan, a statement of any variation from the quarterly revenue
       Budget and up-to-date forecasts for the balance of the relevant Financial
       Year and itemising all transactions referred to in the capital Budget
       entered into by each principal division of the Company's Group during
       that period, within two (2) weeks of the end of the relevant period.

7.3    The foregoing provisions of clauses 7.1 and 7.2 shall be subject to the
provisions of clause 24.2 and shall cease to apply in relation to a principal if
the Shareholding Proportion of such principal falls below 5% or pursuant to
clause 24.2.

CONFIDENTIALITY

CONFIDENTIALITY OBLIGATION

8.1    Each principal and the Company (the RECIPIENT) shall use (and shall
ensure that each of its Subsidiaries shall use) all reasonable endeavours to
keep confidential (and to ensure that its officers, employees, agents and
professional and other advisers keep confidential) any information:

(a)    which it may have or acquire before or after the date of this Agreement
       in relation to the Company's (or any member of the Company's Group's)
       customers, business, assets or affairs; this includes, without
       limitation, any information provided pursuant to clause 7;

(b)    which it may have or acquire before or after the date of this Agreement
       in relation to the customers, business, assets or affairs of any Reuters
       Group Member (if the Recipient is Aether, the Company or any other
       principal) or of any Aether Group Member (if the Recipient is Reuters,
       the Company or any other principal) or of any member of another
       principal's Group (if the Recipient is Aether, Reuters, the Company or
       any other principal) resulting from:

          (i)  negotiating this Agreement;

         (ii)  being a shareholder in the Company;

        (iii)  having appointees on the Board; or

         (iv)  exercising its rights or performing its obligations under this
               Agreement or any Ancillary Agreement; or

                                                                         Page 15
<PAGE>   21

(c)    which relates to the contents of this Agreement or any Ancillary
       Agreement (or any agreement or arrangement entered into pursuant to this
       Agreement or any Ancillary Agreement).

No Recipient shall use for its own business purposes or disclose to any third
party any such information (collectively, CONFIDENTIAL INFORMATION) without the
consent of any other party to which the Confidential Information relates. In
performing its obligations under this clause 8, each Recipient shall apply the
confidentiality standards and procedures it applies generally in relation to its
own confidential information.

EXCEPTIONS FROM CONFIDENTIALITY OBLIGATION

8.2    The obligation of confidentiality under clause 8.1 does not apply to:

(a)    the disclosure (subject to clause 8.3) on a 'need to know' basis to a
       company which is another member of the Recipient's Group where the
       disclosure is for a purpose reasonably incidental to this Agreement;

(b)    information which is independently developed by the relevant Recipient or
       acquired from a third party to the extent that it is acquired with the
       right to disclose the same;

(c)    the disclosure of information to the extent required to be disclosed by
       law, any stock exchange regulation or any binding judgment, order or
       requirement of any court or other competent authority;

(d)    the disclosure of information to any tax authority to the extent
       reasonably required for the purposes of the tax affairs of the Recipient
       concerned or any member of its Group;

(e)    the disclosure (subject to clause 8.3) in confidence to a Recipient's
       professional advisers of information reasonably required to be disclosed
       for a purpose reasonably incidental to this Agreement;

(f)    information which becomes within the public domain (otherwise than as a
       result of a breach of this clause 8);

(g)    any announcement made in accordance with the terms of clause 20; or

(h)    the use by either Reuters or Aether or any member of their respective
       Groups of information relating to any opportunity

                                                                         Page 16
<PAGE>   22

       which has come to Sila for consideration, but which the Board has
       determined not to pursue.

EMPLOYEES, AGENTS AND ADVISERS

8.3    Each Recipient shall inform (and shall ensure that any Subsidiary shall
inform) any officer, employee or agent or any professional or other adviser
advising it in relation to the matters referred to in this Agreement, or to whom
it provides Confidential Information, that such information is confidential and
shall instruct them:

(a)    to keep it confidential; and

(b)    not to disclose it to any third party (other than those persons to whom
       it has already been disclosed in accordance with the terms of this
       Agreement).

The disclosing Recipient is responsible for any breach of this clause 8 by the
person to whom the Confidential Information is disclosed.

RETURN OF CONFIDENTIAL INFORMATION

8.4    If this Agreement terminates, each principal and the Company may by
notice require the others to return or destroy Confidential Information relating
to it and to which the obligations under clause 8.1 continue to apply. If so,
each other principal and the Company (as the case may be) shall (and shall
ensure that its Subsidiaries and its officers and employees and those of its
Subsidiaries shall) so far as commercially reasonable:

(a)    return all documents containing Confidential Information which have been
       provided by or on behalf of the principal demanding the return of
       Confidential Information; and

(b)    destroy any copies of such documents and any document or other record
       reproducing, containing or made from or with reference to the
       Confidential Information

(save, in each case, for any submission to or filings with governmental, tax or
regulatory authorities). Each other principal and the Company (as the case may
be) shall return or destroy the Confidential Information as soon as practicable
after receiving notice.

SURVIVAL AFTER TERMINATION

8.5    The provisions of this clause 8 shall continue to apply if this Agreement
is terminated for a period of three (3) years from the date of termination.

                                                                         Page 17
<PAGE>   23

REGULATORY MATTERS

CO-OPERATION

9.     Subject always to clause 8, the principals shall co-operate with each
other to ensure that all information necessary or desirable for making (or
responding to any requests for further information following) any notification
or filing made in respect of this Agreement, or the transactions contemplated by
it, is supplied to the principal dealing with such notification or filing and
that any such notification, filing or other correspondence with a competent
authority is properly, accurately and promptly made.

POST CLOSING MATTERS

CLAIMS BY THE COMPANY

10.1   If the Company or any of its Subsidiaries has or may have any claim
against a principal or any member of that principal's Group, that principal will
ensure that its nominated Directors shall not do anything to prevent or hinder
the Company's Group asserting or enforcing the claim against the first mentioned
principal, save for stating such objection at meetings of the Board, and that
they shall, if necessary, enable all decisions regarding such claim not to
include any Directors nominated by such principal. This is without prejudice to
any right of such principal itself or members of its Group to dispute the claim.

TAX MATTERS

SURRENDER OF AND PAYMENT FOR RELIEF

10.2   For the purposes of clauses 10.2 to 10.8, AVAILABLE LOSSES means the
aggregate of any amounts which, in accordance with Chapter IV of Part X of the
Income and Corporation Taxes Act 1988 (CHAPTER IV), are eligible for surrender
by a member of the Company's Group under that Chapter IV, but shall not include
any amount which is to be or has been surrendered by any member of the Company's
Group to any other member of the Company's Group.

10.3   The Company shall, or shall procure that:

(a)    any company with Available Losses shall, to the extent permissible by law
       (including, but not limited to, Chapter IV), surrender such proportion of
       Available Losses to such member of the Reuters Group or Aether Group as
       Reuters Parent or Aether Parent shall direct; and

                                                                         Page 18
<PAGE>   24

(b)    all such notices of consent to surrender and all such other documents and
       returns are signed and submitted to the relevant tax authority as may be
       necessary to secure that full effect is given to sub-clause 10.3(a)
       above.

10.4   In consideration of any such surrender as referred to in clause 10.3,
Reuters Parent (where the surrender is made to a member of the Reuters Group) or
Aether Parent (where the surrender is made to a member of the Aether Group)
shall pay or shall procure that there shall be paid to the member of the
Company's Group surrendering such Available Losses, a sum equal to the amount of
corporation tax from which the company that is the claimant company in respect
of such surrender (the CLAIMANT) has been relieved by virtue of that surrender
being validly and effectively made.

10.5   Any payment made pursuant to clause 10.4 shall be paid on the date on
which any corporation tax chargeable on any taxable profits of the Claimant for
its accounting period to which that surrender relates becomes due and payable
(or would have become due and payable had the claimant company incurred any
liability to corporation tax in respect of that accounting period). In respect
of any Claimant to which the Corporation Tax (Instalment Payments) Regulations
1998 (SI 1998/3175) (the INSTALMENT REGULATIONS) applies, the due and payable
date referred to above shall be deemed to be:

(a)    the due and payable date as defined in paragraph 4(1)(b), 4(2)(b) and
       4(3)(b) of the Instalment Regulations in relation to accounting periods
       of the Claimant ending on or before 1 July 2002; and

(b)    the final instalment date as defined in paragraph 5(3) of the Instalment
       Regulations in respect of all other accounting periods.

STAMP DUTY

10.6   Aether Parent, Reuters Parent and the Company will, and shall procure
that any member of its Group will, use all reasonable efforts not to cause or
knowingly permit any executed original or counterpart of any document of
transfer in relation to (i) the transfer of units of Aether IFX LLC from Aether
Parent to Aether and (ii) the transfer of units of Aether IFX LLC from Aether to
the Company to be brought into the United Kingdom except where any such party
considers in its reasonable opinion that:

(a)    it is necessary to do so for the purposes of any judicial, arbitration or
       administrative proceedings; or

                                                                         Page 19
<PAGE>   25

(b)    it is necessary to do so for the purposes of determining any liability to
       tax (other than stamp duty); or

(c)    that party is required to do so by law or any regulatory requirement,

and in those circumstances that party shall, unless prohibited from doing so by
law or any regulatory requirement) notify the other parties of the intention to
bring such documents into the United Kingdom in writing not less than seven
Business Days before doing so.

10.7   To the extent that any stamp duty arises or is increased as a result of a
breach by any party of clause 10.6, that party shall pay such stamp duty on
demand.

10.8   To the extent that clause 10.7 does not apply to such stamp duty, the
Company shall pay such stamp duty.

TRANSFER OF SECURITIES

GENERAL

11.1   The provisions of this clause 11 apply in relation to any transfer, or
proposed transfer, of (or the creation or disposal of any other right or
interest in) Ordinary Shares or Preference Shares or other Relevant Securities
in the Company or any of its Subsidiaries (each such type or class of share or
security being a RESTRICTED SECURITY) or any interest in Restricted Securities,
but the provisions of this clause 11 shall be subject to clause 24.2.

RESTRICTION ON TRANSFER

11.2(a)       Except as permitted by this clause 11, each principal undertakes
       that it shall not (and shall procure that any member of its Group shall
       not) without the prior written consent of each Relevant Principal and the
       Company and the Company undertakes that it shall not (and shall procure
       that any member of its Group shall not) without the prior written consent
       of each Relevant Principal:

          (i)  transfer any Restricted Securities;

         (ii)  grant, declare, create or dispose of any right or interest in any
               Restricted Securities; or

        (iii)  create or permit to exist any Security Interest over any
               Restricted Securities.

                                                                         Page 20
<PAGE>   26

(b)    The Company will ensure that any certificates for Ordinary Shares or
       Preference Shares will be endorsed with the following legends until such
       time as the appropriate registrations have been made in respect of the
       share in question (in the case of the first paragraph) or clauses 11 and
       12 of this Agreement cease to have effect (in the case of the second
       paragraph):

       "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
       UNDER THE UNITED STATES OF AMERICA SECURITIES ACT OF 1933 OR UNDER ANY
       SECURITIES OR BLUE SKY LAWS OF ANY STATE OF THE UNITED STATES OF AMERICA
       AND MAY NOT BE TRANSFERRED UNLESS REGISTERED UNDER THE SECURITIES ACT AND
       ANY APPLICABLE STATE SECURITIES LAWS OR PURSUANT TO AVAILABLE EXEMPTIONS
       FROM SUCH REGISTRATION."

       "THIS CERTIFICATE AND THE SECURITIES REPRESENTED HEREBY ARE SUBJECT TO
       AND TRANSFERABLE ONLY IN ACCORDANCE WITH THE PROVISION OF A SHAREHOLDERS
       AGREEMENT, DATED ___________, 2000, A COPY OF WHICH, AS IT MAY BE AMENDED
       FROM TIME TO TIME, IS MAINTAINED WITH THE CORPORATE RECORDS OF THE
       COMPANY."

INITIAL PERIOD

11.3   Save for transfers for which consent is given under clause 11.2 or for
intra-Group transfers permitted under clause 11.11, 11.12 and 11.13, each
principal undertakes that it shall not and shall procure that no member of its
Group shall transfer any Restricted Securities during a period of 18 months from
the date of this Agreement.

TRANSFER NOTICE

11.4   After the end of the initial period mentioned in clause 11.3 and before
any principal (and/or any member of its Group) or the Company (and/or any member
of its Group) (such principal or the Company being the SELLER) makes any
transfer of all or any of the Restricted Securities held by them (the SELLER'S
SECURITIES) (other than in connection with any Flotation and subject to clauses
11.11, 11.12 and 11.13), the Seller shall first give each Relevant Principal and
the Company notice (a TRANSFER NOTICE) of the proposed transfer together with
details of any proposed third party purchaser (the THIRD PARTY PURCHASER), the
purchase price and other material terms which the Seller (or the relevant member
of its Group) and the Third Party Purchaser have

                                                                         Page 21
<PAGE>   27

agreed. A Transfer Notice is irrevocable except as provided in this clause 11.

RIGHT OF RELEVANT PRINCIPALS TO PURCHASE OR TAG ALONG

11.5   On receipt of the Transfer Notice, each Relevant Principal shall have the
right to elect either:

(a)    by giving notice (an ACCEPTANCE NOTICE) to the Seller within twenty (20)
       days of receiving the Transfer Notice (the ACCEPTANCE PERIOD), to buy up
       to the same proportion of the Seller's Securities as such Relevant
       Principal's Shareholding Proportion bears to the sum of Shareholding
       Proportions of all of the Relevant Principals (other than the Seller)
       and, in the event that any other Relevant Principal does not give an
       Acceptance Notice in respect of all of its proportionate entitlement to
       buy Seller's Securities, such additional number of the Seller's
       Securities as such Relevant Principal specifies in the Acceptance Notice
       (provided that if the aggregate additional number of Seller's Securities
       specified in the relevant Acceptance Notices exceeds the number
       available, the entitlements shall be scaled back pro-rata to the
       Shareholding Proportions of the Relevant Principals which have specified
       that they will buy an additional number of Seller's Securities), in
       either case at the price and on the terms specified in the Transfer
       Notice provided that such Acceptance Notice may specify that, if no
       obligations to buy and sell the Seller's Securities arise under clause
       11.7, the Relevant Principal giving the Acceptance Notice wishes such
       notice to be treated as a Tag Along Notice pursuant to paragraph (b)
       below. The obligations of the principals and, where applicable, the
       Company to complete the purchase are subject to the provisions of clauses
       11.6 and 11.7; or

(b)    by giving notice (a TAG ALONG NOTICE) to the Seller within the Acceptance
       Period, to require that the Seller uses its reasonable endeavours to
       procure that the Third Party Purchaser will buy the same proportion (the
       TAG ALONG PROPORTION) of any Restricted Securities of the same type and
       class as the Seller's Securities or which are like securities or the
       functional equivalent of such securities (the TAG ALONG SECURITIES) held
       by the Relevant Principal and members of its Group as the number of
       Seller's Securities bears to the number of such Restricted Securities
       held by the Seller and/or any member of its Group at the price (including
       the value of any non-cash consideration specified in the Transfer Notice
       which is money or money's worth) and on the terms specified in the
       Transfer Notice, provided however that

                                                                         Page 22
<PAGE>   28

       such purchase by the Third Party Purchaser shall be conditional upon the
       transfer of the Seller's Securities (or such lesser number of them as is
       required under clause 11.8) from the Seller to the Third Party Purchaser
       in accordance with the terms set out in the Transfer Notice. For the
       purposes of this paragraph (b), each Preference Share shall be deemed to
       be the functional equivalent of the number of Ordinary Shares which would
       have been issued to the holder of such Preference Share had it been
       converted on the date of the Transfer Notice.

COMPANY'S RIGHT TO BUY SELLER'S SECURITIES

11.6   On receipt of a Transfer Notice, the Company will have the right, to the
extent legally permissible, to elect, by giving notice to the Seller within
twenty (20) days of receiving the Transfer Notice in the event that the Relevant
Principals do not exercise the rights to buy all of the Seller's Securities
under clause 11.5(a) or any Acceptance Notice ceases to have effect pursuant to
clause 11.7, to buy all (but not some only) of the Seller's Securities not
bought by the Relevant Principals at the price and on the terms specified in the
Transfer Notice (or at such other price and on such other terms as the Seller
and the Company agree).

PURCHASE OF SELLER'S SECURITIES

11.7   If (and only if) one or more Relevant Principals give Acceptance Notices
and/or the Company exercises its right under clause 11.6, with respect to, in
the aggregate all of the Seller's Securities, each Relevant Principal which has
given an Acceptance Notice to the Seller and/or the Company under clause 11.6,
shall become bound (subject only to (i) any necessary approvals of its
shareholders in general meeting, (ii) any government, governmental or regulatory
consents which are necessary for such sale and purchase (REGULATORY APPROVALS)
and (iii) any conditions set forth in the Transfer Notice or which are
customary) to buy and the Seller shall be bound to sell (and/or to procure that
any member of its Group shall sell) the relevant number of the Seller's
Securities from the time at which the Relevant Principal gives the Seller an
Acceptance Notice and/or the Company gives the Seller notice under clause 11.6.
In such event, completion of the sale and purchase of the Seller's Securities
shall take place as soon as possible after the Acceptance Notice is given
subject to satisfaction of the aforementioned conditions. Notwithstanding the
foregoing, such notice and any right of a Relevant Principal to acquire the
Seller's Securities shall cease to have effect if:

                                                                         Page 23
<PAGE>   29

(A)    any necessary approval of the Relevant Principal's shareholders in
       general meeting has not been obtained within thirty (30) days of the
       giving of the Acceptance Notice; or

(B)    any necessary Regulatory Approval is not obtained within one-hundred and
       eighty (180) days of the giving of the Acceptance Notice; or

(C)    earlier than the expiry of the latter period, any relevant authority has
       conclusively refused to grant any Regulatory Approval; or

(D)    any other condition to such sale and purchase is not satisfied or (where
       applicable) waived within sixty (60) days of the giving of the Acceptance
       Notice.

RIGHT TO TAG ALONG

11.8   If any Relevant Principal gives the Seller a Tag Along Notice in
accordance with clause 11.5(b) and no obligations to buy and sell the Seller's
Securities arise under clause 11.7 then the Seller shall use its reasonable
endeavours to procure that the Third Party Purchaser will buy such Relevant
Principal's Tag Along Proportion of its Tag Along Securities and if,
notwithstanding such endeavours:

(a)    the Third Party Purchaser does not agree to buy a number of securities
       greater than the number of the Seller's Securities, the Seller shall
       procure that each of the Seller and any Relevant Principal which gave the
       Seller a Tag Along Notice under clause 11.5 will be able to sell to the
       Third Party Purchaser such proportion of:

          (i)  in the case of the Seller, the Seller's Securities; and

         (ii)  in the case of a Relevant Principal, the Tag Along Proportion of
               the Tag Along Securities,

       as the number of the Seller's Securities bears to the sum of (x) the
       number of the Seller's Securities and (y) the number of the Tag Along
       Proportion of the Tag Along Securities of each Relevant Principal; or

(b)    the Third Party Purchaser does not agree to buy securities from any
       Person other than the Seller, the Seller shall be bound to buy from each
       Relevant Principal which gives the Seller a Tag Along Notice such
       proportion of the Tag Along Proportion of the Tag Along Securities of
       such Relevant Principal as the number of the Seller's Securities bears to
       the sum of (x) the number of the

                                                                         Page 24
<PAGE>   30

       Seller's Securities and (y) the number of the Tag Along Proportion of the
       Tag Along Securities of such Relevant Principal,

and in any such case the Relevant Principals shall be bound to sell (and/or to
procure that any member of its Group shall sell) and the Seller shall be bound
to sell and/or purchase (and/or to procure that any member of its Group shall
sell) such securities (subject only to any necessary approvals of the
shareholders of any Relevant Principal in general meeting and any Regulatory
Approvals and to any conditions set out in the Transfer Notice or which are
customary). Completion of such sales and purchases shall take place as soon as
possible after the Tag Along Notice is given subject to satisfaction of the
aforementioned conditions.

SELLER'S RIGHT TO SELL TO THIRD PARTY PURCHASER

11.9   If no obligations to buy and sell the Seller's Securities arise under
clause 11.7, the Seller may (subject to clause 11.8 above and clause 11.10
below) transfer the Seller's Securities on a bona fide arm's length sale to the
Third Party Purchaser at a price not less than the purchase price and on terms
not materially different than the terms specified in the Transfer Notice
provided that the transfer is completed within sixty (60) days after the earlier
of:

(a)    receipt of a definitive response from all Relevant Principals and the
       Company; or

(b)    if no response is received from any Relevant Principal or the Company,
       the end of the period of twenty (20) days after the latest receipt of the
       Transfer Notice by a Relevant Principal or the Company; or

(c)    if any right of a Relevant Principal to purchase Seller's Securities
       lapses pursuant to clause 11.7, the date of such lapse.

The principals shall give (or ensure that any Shareholders in their respective
Groups shall give) such approvals required by the Articles to any transfer of
Shares or other securities permitted by the terms of this clause 11.

SALE TERMS

11.10  The sale of (i) any Seller's Securities to a Relevant Principal or to a
Third Party Purchaser or to the Company and (ii) any Restricted Securities of a
Relevant Principal to a Third Party Purchaser or a Seller in accordance with
this clause 11 shall be on the following terms:

                                                                         Page 25
<PAGE>   31

(a)    the Seller's Securities and/or Restricted Securities will be sold free
       from all liens, charges and encumbrances and third party rights and
       together with all rights of any nature attaching to them including all
       rights to any dividends or other distributions declared, paid or made
       after the date of the Transfer Notice;

(b)    the Seller and/or the Relevant Principal shall deliver (or procure the
       delivery of) to the Buyer duly executed transfer(s) in favour of the
       Buyer, or as it may direct, together with any appropriate certificate(s)
       in respect of the relevant Seller's Securities or Restricted Securities
       (as the case may be) and a certified copy of any authority under which
       such transfer(s) is/are executed;

(c)    against delivery of the transfer(s), the Buyer shall pay the total
       consideration for the relevant Seller's Securities to the Seller and/or
       for the relevant Restricted Securities to the selling Relevant Principal
       for value on the completion date;

(d)    the principals shall ensure (insofar as they are able) that (where
       applicable) the relevant transfer or transfers (subject to their being
       duly stamped) are registered in the name of the Buyer or as it may
       direct; and

(e)    the Seller and/or the Relevant Principal shall do all such other things
       and execute all other documents (including any deed) as the Buyer may
       reasonably request to give effect to the sale and purchase of the
       relevant Seller's Securities and/or Restricted Securities.

For the purposes of this clause 11.10, BUYER means the Relevant Principal or the
Company or a Third Party Purchaser or the Seller which buys some or all of the
Seller's Securities to which a Transfer Notice relates or some or all of the Tag
Along Securities to which a Tag Along Notice relates.

INTRA-GROUP TRANSFERS

11.11  Subject to clauses 11.15 and 15.2, a Shareholder may at any time transfer
any of the Restricted Securities held by it to any member of its Group.

11.12  Subject to clauses 11.15 and 15.2, the Company or any member of its Group
may at any time transfer any of the Restricted Securities held by it to any
other member of the Company's Group.

                                                                         Page 26
<PAGE>   32

SHAREHOLDER CEASING TO BE A SUBSIDIARY

11.13  Each principal and , where the principal is Reuters, Reuters Parent and,
where the principal is Aether, Aether Parent undertakes to ensure that any
Shareholder in its Group shall transfer all of the Restricted Securities which
such Shareholder then holds to such principal (or to another member of such
principal's Group) before such Shareholder ceases being a member of such
principal's Group at any time (including, for the avoidance of doubt, as a
result of a designation by Reuters or Aether pursuant to the definition of
"Subsidiary" in clause 1.1).

11.14  The Company undertakes to ensure that any member of its Group shall
transfer all Restricted Securities which such member then holds to the Company
or to another member of the Company's Group before such member ceases being a
member of the Company's Group at any time.

OBLIGATIONS OF TRANSFEREE

11.15  Completion of any transfer of the Seller's Shares and/or Restricted
Securities to a Third Party Purchaser shall be subject to the condition that the
Third Party Purchaser shall enter into a Deed of Adherence in the form of
Schedule 2 under which the Third Party Purchaser becomes bound by the provisions
of this agreement.

INSOLVENCY AND DEFAULT

DEFAULT EVENTS

12.1   The provisions of this clause 12 shall apply on the occurrence of a
Default Event but shall be subject to clause 24.2. It is a Default Event in
relation to a principal if:

(a)    a court of competent jurisdiction makes an order or a resolution is
       passed, for the dissolution or administration of that principal
       (otherwise than in the course of a reorganisation or restructuring
       previously approved in writing by the other principal, such approval not
       to be unreasonably withheld or delayed); or

(b)    any person other than a member of any other principal's Group takes any
       step (and it is not withdrawn or discharged within ninety (90) days) to
       appoint a liquidator, manager, receiver, administrator, administrative
       receiver or other similar officer in respect of any assets which include
       either (i) the Shares held by that principal or any Subsidiary of it or
       (ii) shares in that principal or any holding company of it;

                                                                         Page 27
<PAGE>   33

(c)    that principal convenes a meeting of its creditors or makes or proposes
       any arrangement or composition with, or any assignment for the benefit
       of, its creditors; or

(d)    that principal commits a breach of clause 11.2

and reference to a PRINCIPAL in this clause (other than any reference to any
other principal) includes any Shareholder in that principal's Group or any
holding company of that principal.

RIGHT TO MAKE OFFER

12.2   If a Default Event occurs in relation to a principal (the AFFECTED
PRINCIPAL), the Affected Principal shall be obliged to notify each other
principal promptly of such Default Event. At any time before the expiry of a
period of ninety (90) days after the date the other principals are notified that
the Default Event has occurred, each other principal (each a BUYER) may make an
offer to purchase the Ordinary Shares and the Preference Shares collectively
held by the Affected Principal and/or any members of its Group (other than the
Company's Group where the Affected Principal is Aether) (the RELEVANT
SECURITIES) pro rata in their respective Shareholding Proportions as at the
close of business on the date prior to such offer. If the Default Event arises
under clause 12.1(d), in addition to the other rights set forth herein, each
principal other than the Affected Principal shall also have the right to sell
(each a DEFAULT Seller) to the Affected Principal, and the Affected Principal
shall be obligated to purchase, a number of Shares equal to the number such
Seller could have otherwise sold and at the same price as would have applied
pursuant to clause 11.9. The Affected Principal shall pay each Default Seller in
full within five (5) days of the date on which the Affected Principal receives
notice requesting payment pursuant to this clause 12.2 from such Default Seller.

OFFER NOTICE

12.3   Any offers for the Relevant Securities referred to in clause 12.2 shall
take the form of a notice to the Affected Principal (the OFFER NOTICE). The
price per Relevant Security payable to the Affected Principal by each Buyer
shall be such price as is agreed between the Buyers who give Offer Notices and
the Affected Principal within fifteen (15) days of the last day on which an
Offer Notice can be given under clause 12.2 (the AGREED PRICE), or, failing
agreement, the Fair Price determined in accordance with clause 12.5. The Offer
Notice shall include a statement that the offer may be accepted within thirty
(30) days of the later of the Affected Principal receiving the Offer Notice or

                                                                         Page 28
<PAGE>   34

the agreement or determination of the Agreed Price or Fair Price (as the case
may be).

12.4   Each of the Buyers shall additionally be entitled to offer to purchase
Relevant Securities in excess of its pro rata entitlement by specifying in its
Offer Notice the number of shares in excess of its pro rata entitlement which it
is prepared to purchase. To the extent that any Buyer has not given an Offer
Notice or has offered to purchase less than its pro rata entitlement, the excess
shall be allocated (as nearly as possible) to satisfy any offers for additional
Relevant Securities, and, if there are insufficient Relevant Securities, then
such Relevant Securities shall be allocated to each Buyer making an offer for
additional Relevant Securities pro rata to their Shareholding Proportions,
provided that no Buyer shall be required to take more Relevant Securities than
it shall have specified in its Offer Notice.

REFERENCE TO EXPERT

12.5   If the Buyers who give the Offer Notices and the Affected Principal fail
to agree the Agreed Price within fifteen (15) days in accordance with clause
12.3, an internationally recognised firm of accountants or investment bankers
(the EXPERT) shall be appointed to determine the Fair Price. The Expert shall be
such internationally recognised firm of accountants or investment bankers as
such Buyers and the Affected Principal may agree or, if they fail to agree
within fifteen (15) days of the end of the fifteen (15) day period, the Expert
shall be such internationally recognised firm of accountants or investment
bankers, independent of both of the principals, as the President for the time
being of the International Chamber of Commerce appoints at the request of any of
the Buyers. Any such request must be made within fifteen (15) days of the end of
the fifteen (15) day period (or such longer period as such Buyers and the
Affected Principal may agree in writing). The Expert shall act as an expert and
not as an arbitrator and its decision, which shall be incorporated in a
certificate (the CERTIFICATE), shall be final and binding on the principals.
Such Buyers and the Affected Principal shall bear the Expert's fees and expenses
equally.

RIGHT TO PURCHASE AT FAIR PRICE

12.6   If an Expert is appointed under clause 12.5, each Buyer who gives an
Offer Notice shall have the right to buy the Relevant Securities from the
Affected Principal at the Fair Price. Each such Buyer shall exercise the right
to buy by giving notice to the Affected Principal within thirty (30) days of the
issue by the Expert of the Certificate to the Affected Principal and each such
Buyer.

                                                                         Page 29
<PAGE>   35

COMPLETION

12.7   Subject only to any Regulatory Approvals or approval of each relevant
Buyer's shareholders in general meeting (APPROVALS), the Affected Principal
shall be bound to sell and each such Buyer shall be bound to buy its pro rata
entitlement of the Relevant Securities or, if different, such number allocated
to it in accordance with clause 12.4:

(a)    at the Agreed Price; or

(b)    at the Fair Price, if a Buyer notifies the exercise of its rights under
       clause 12.6.

In such event, completion of the sale and purchase of the Relevant Securities
shall take place within sixty (60) days of the day on which the Affected
Principal and each Buyer become so bound (the REFERENCE DATE) or, if any
Approval has not been obtained by the end of that period, within ten (10) days
of the date on which the last Approval to be obtained is obtained. If any
Approval has not been obtained within one-hundred and eighty (180) days after
the Reference Date, each Offer Notice shall lapse and have no further effect.
Notwithstanding the foregoing, the failure of a relevant Buyer's shareholders to
approve the sale and purchase of the Relevant Securities shall not prevent any
other relevant Buyer from completing the sale and purchase of the Relevant
Securities.

TRANSFER TERMS

12.8   The transfer of the Relevant Securities shall be on the following terms:

(a)    the Relevant Securities shall be sold free from all liens, charges and
       encumbrances and third party rights, together with all rights of any
       nature attaching to them including all rights to any dividends or other
       distributions declared, paid or made after the date of the Offer Notice;

(b)    the Affected Principal shall deliver to each Buyer duly executed
       transfer(s) in favour of such Buyer, or as it may direct, together with,
       if appropriate, share certificate(s) for the Relevant Securities and a
       certified copy of any authority under which such transfer(s) is/are
       executed;

(c)    against delivery of the transfer(s), each Buyer shall pay its respective
       share of the total consideration for the Relevant Securities to the
       Affected Principal by banker's draft or wire transfer for value on the
       completion date;

                                                                         Page 30
<PAGE>   36

(d)    the principals shall ensure (insofar as they are able) that the relevant
       transfer or transfers are registered in the name of each Buyer or as it
       may direct;

(e)    the Affected Principal shall do all such other things and execute all
       other documents (including any deed) as each Buyer may reasonably request
       to give effect to the sale and purchase of the Affected Principal's
       Relevant Securities.

DEFAULT

13.    Subject to clause 12.1(d), if a party (or any member of its Group)
commits a breach of any of this Agreement (the DEFAULTING PARTY), any other
party may serve notice upon the Defaulting Party. The notice shall specify the
breach and require the Defaulting Party immediately to stop the breach and, to
the extent that it is possible, to make good the results of the breach within
fifteen (15) days. This does not affect any other parties' right subsequently to
claim damages or other compensation under applicable law for the breach in
question or, where appropriate, to seek an immediate remedy of an injunction,
specific performance or similar court order to enforce the Defaulting Party's
obligations.

FURTHER ASSURANCES

EXERCISE OF RIGHTS AND POWERS

14.1   So far as it is legally able, each party undertakes with the others to
exercise all voting rights and powers (direct and indirect) available to it in
relation to any person and/or the Company to ensure that the provisions of this
Agreement (and the other agreements referred to in this Agreement) are
completely and punctually fulfilled, observed and performed and generally that
full effect is given to the principles set out in this Agreement.

PERFORMANCE BY SUBSIDIARIES

14.2   Each of Reuters Parent, Aether Parent, each principal and the Company
shall ensure that its Subsidiaries perform:

(a)    all obligations under this Agreement which relate to members of its
       respective Group (whether as Shareholders or otherwise); and

(b)    all obligations under any agreement entered into by any of its
       Subsidiaries pursuant to this Agreement.

                                                                         Page 31
<PAGE>   37

14.3   Without limitation to clause 14.2, each of Reuters Parent and Reuters (in
respect of any undertaking designated by Reuters) and Aether Parent and Aether
(in respect of any undertaking designated by Aether) shall ensure that any
undertaking designated by Reuters or Aether (as the case may be) in accordance
with the definition of Subsidiary in clause 1.1 will perform all obligations
under this Agreement which have arisen up to the time of such designation.

14.4   The liability of any person under clause 14.2 or 14.3 shall not be
discharged or impaired by any amendment to or variation of this Agreement or the
Master Contribution Agreement, any release of or granting of time or other
indulgence to any of its Subsidiaries or any third party or any other act, event
or omission which but for this clause would operate to impair or discharge the
liability of such party under this clause 14.2 or 14.3.

NON-ASSIGNMENT

15.1   Subject to clause 15.2 no party or any Shareholder in its Group may, or
may purport to, assign any of its rights or obligations under this Agreement in
whole or in part, nor grant, declare, create or dispose of any right or interest
in it (otherwise than in connection with a transfer of Shares in accordance with
the terms of this Agreement). No assignment shall be made to any third party of
any rights which are expressed to be rights of Reuters, Aether or the Company
(or members of their respective Groups) and an assignment to a third party
permitted in accordance with this clause 15.1 shall be subject to the assignee
agreeing with the principals, by entering into a Deed of Adherence in the form
of Schedule 2, to become bound by the provisions of this Agreement. A third
party assignee shall be subject to the rights of other investors as set out in
this Agreement. The obligations of the relevant assignor under this Agreement
shall cease to the extent that the same have been assumed by the Assignee under
the relevant Deed of Adherence provided that this shall not limit the
obligations of Aether Parent, Reuters Parent, a principal or the Company under
clause 14.2.

15.2   The principals shall be entitled to assign the benefit of any provision
of this Agreement (in whole or in part) to any member of their respective Groups
provided that such assignment shall be subject to the assignee agreeing with the
principals, by entering into a Deed of Adherence in the form of Schedule 2, to
become bound by the provisions of this Agreement.

                                                                         Page 32
<PAGE>   38

WAIVER OF RIGHTS

16.    No waiver by a party of a failure by any other party to perform any
provision of this Agreement operates or is to be construed as a waiver in
respect of any other failure whether of a like or different character.

AMENDMENTS

17.    A variation of this Agreement is valid only if it is in writing and
signed by or on behalf of each party.

INVALIDITY

18.    If any provision of this Agreement is or is held to be invalid or
unenforceable, then so far as it is invalid or unenforceable it has no effect
and is deemed not to be included in this Agreement. This shall not invalidate
any of the remaining provisions of this Agreement. The parties shall then use
all reasonable endeavours to replace the invalid or unenforceable provision by a
valid provision the effect of which is as close as possible to the intended
effect of the invalid or unenforceable provision.

NO PARTNERSHIP OR AGENCY

19.1   Nothing in this Agreement (or any of the arrangements contemplated by it)
shall be deemed to constitute a partnership between any of the parties or
constitute any party the agent of any other party for any purpose, or entitle
any party to commit or bind any other party (or any member of its respective
Group) in any manner.

19.2   Unless the parties agree otherwise in writing none of them shall:

(a)    enter into contracts with third parties or members of its Group as agent
       for another party or members of its Group; or

(b)    describe itself as such an agent or in any way hold itself out as being
       such an agent; or

(c)    state, indicate or imply that the Company or any of its Subsidiaries is a
       Subsidiary of, controlled by, or otherwise part of, the Reuters Group.

ANNOUNCEMENTS

20.1   No formal public announcement or press release in connection with the
signature or subject matter of this Agreement shall (subject to clause 20.2) be
made or issued by or on behalf of any of the parties or

                                                                         Page 33
<PAGE>   39

any of its Subsidiaries without the prior written approval of the other parties
(such approval not to be unreasonably withheld or delayed).

20.2   If a party has an obligation to make or issue any announcement required
by law or by any stock exchange or by any governmental authority, the relevant
party shall give the other parties every reasonable opportunity to comment on
any announcement or release before it is made or issued (provided that this
shall not have the effect of preventing the party making the announcement or
release from complying with its legal and/or stock exchange obligations.)

COSTS

21.    Except as otherwise provided herein or in the Master Contribution
Agreement, each of the parties shall pay its own legal and accountancy costs,
charges and expenses (including taxation) incurred in connection with
negotiating, preparing and implementing this Agreement and the transactions
contemplated by it.

ENTIRE AGREEMENT

22.1   This Agreement, the Master Contribution Agreement, the Ancillary
Agreements and the documents referred to herein and therein set out the entire
agreement and understanding between the parties with respect to the subject
matter of it.

22.2   None of the parties have relied on or has been induced to enter into this
Agreement in reliance on any representation, warranty or undertaking which is
not set out in this Agreement;

22.3   No party shall be liable to the other for any misrepresentation or untrue
statement which is not set out in this Agreement.

22.4   Liability for fraudulent misrepresentation is not excluded.

CONFLICT WITH ARTICLES

SUPREMACY OF THIS AGREEMENT

23.1   If the provisions of this Agreement conflict with the Articles or other
constitutional documents or those of any other Subsidiary of the Company, the
provisions of this Agreement shall prevail as between the parties. The parties
shall:

(a)    exercise all voting and other rights and powers available to them to give
       effect to the provisions of this Agreement, and

                                                                         Page 34
<PAGE>   40

(b)    (if necessary and to the extent permissible under applicable law) ensure
       any required amendment to the Articles or other constitutional document
       of the Company or any other Subsidiary of the Company.

TRANSFERS OF SHARES

23.2   Without prejudice to the generality of clause 23.1, the provisions of
this Agreement shall prevail in relation to the transfer of Shares and,
accordingly:

(a)    no principal shall use the provisions of Article 27 of the Articles to
       frustrate the operation of clauses 11 or 12 of this Agreement; and

(b)    each party will promptly give (or ensure that any Shareholder in its
       Group promptly gives) any approval under Article 27 of the Articles which
       is necessary or appropriate to give full immediate effect to the
       procedure contemplated by the provisions of clauses 11 or 12 and/or any
       transfer of Shares permitted under this Agreement.

APPOINTMENT AND REMOVAL OF DIRECTORS

23.3   Without prejudice to the generality of clause 23.1, the provisions of
this Agreement shall prevail in relation to the appointment and removal of
directors and, accordingly:

(a)    no principal or party shall use the provisions of the Articles to
       frustrate the operation of clause 4 of this Agreement; and

(b)    each principal and party will promptly give (or ensure that any
       Shareholder in its Group promptly gives) any approval under the Articles
       which is necessary, or appropriate to give full immediate effect to any
       appointment or removal of directors pursuant to clause 4.

TERMINATION OF AGREEMENT

DURATION

24.1   Subject to clause 24.2, this Agreement shall continue in full force and
effect and will only terminate upon (i) a resolution being passed to wind up the
Company (in accordance with clause 5.1) or (ii) one principal (or any member of
its Group) owning the entirety of the Shares or (iii) the agreement of the
principals. This shall not:

                                                                         Page 35
<PAGE>   41

(a)    relieve any party from any liability or obligation for any matter,
       undertaking or condition which has not been done, observed or performed
       by that principal before termination;

(b)    affect the terms of any agreement replacing this Agreement entered into
       between Reuters and Aether, or any successor of either of them holding
       Shares;

(c)    affect the terms of clause 8 of this Agreement (Confidentiality).

24.2   On the occurrence of a Flotation, the provisions contained in clauses 3.1
to 3.5 (Issue of Shares), clause 4.3 (Board Observer), clauses 5.1 and 5.2
(Reserved Matters), clauses 7.1 (Inspection and Information) and 7.2 (Accounts,
Business Plan and Budgets), clause 11 (Transfer of Shares) and clause 12
(Insolvency and Default) will terminate and cease to have effect.

SILA TRADE MARK

25.1   In order to protect the freedom of the Company to conduct its operations
as agreed in clause 2, each of Reuters Parent and Aether Parent undertakes that
(save as may be permitted under clause 25.2 or otherwise agreed between the
Company, Reuters Parent and Aether Parent) it shall not, and shall procure that
none of its Affiliates (other than the Company's Group) shall, apply to register
as a trade mark or Internet domain name incorporating, or otherwise use, any
Sila Trade Mark at any time whilst it remains a Shareholder in the Company.

25.2   If:

(a)    the principals agree that the Company shall cease to carry on the
       Business and that, accordingly, this Agreement shall terminate; or

(b)    a resolution is passed to wind up the Company (in accordance with clause
       5.1),

then the principal with the largest Shareholding Proportion shall be entitled to
own and use the Sila Trade Marks following such termination or winding-up of the
Company and the principals and the Company shall negotiate in good faith to
agree the mechanism by which an appropriate transfer will be made in accordance
with applicable law of such right, title and interest the Company's Group may
have in the Sila Trade Marks (including, without limitation any registrations
and applications for trade marks or Internet domain names incorporating the Sila
Trade Mark), provided that no principal shall be obliged to agree to any step
which may have a material adverse effect on such principal.

                                                                         Page 36
<PAGE>   42

The provisions of this clause 25.2 shall survive any termination of this
Agreement as referred to in this clause 25.2.

NOTICES

26.1   Any notice or other formal communication to be given under this Agreement
shall be in writing and signed by or on behalf of the party giving it. It shall
be:

(a)    sent by fax to the number set out in clause 26.2; or

(b)    delivered by hand or sent by prepaid recorded delivery, special delivery
       or registered post to the relevant address in clause 26.2.

In each case it shall be marked for the attention of the relevant principal set
out in clause 26.2 (or as otherwise notified from time to time under this
Agreement). Any notice given by hand delivery, fax or post shall be deemed to
have been duly given:

(a)    if hand delivered, when delivered;

(b)    if sent by fax, twelve (12) hours after the time of despatch;

(c)    if sent by recorded delivery, special delivery or registered post, at 10
       am on the second Business Day from the date of posting

unless there is evidence that it was received earlier than this and provided
that, where (in the case of delivery by hand or by fax) the delivery or
transmission occurs after 6 pm on a Business Day or on a day which is not a
Business Day, service shall be deemed to occur at 9 am on the next following
Business Day. References to time in this clause are to local time in the country
of the addressee.

ADDRESS OF NOTICES

26.2   The addresses and fax numbers of the parties for the purpose of clause
26.1 are:

(a)    REUTERS:

       Address:           Reuters Overseas Holdings B.V.
                          Drentestraat 11
                          1083 HK AMSTERDAM
                          Netherlands

       For the attention of:      General Counsel

       Fax:               31 20 504 5910

                                                                         Page 37
<PAGE>   43

       with a copy to:    Reuters America Inc.
                          40 East 52nd Street
                          New York, New York 10022

       For the attention of:      Devin Wenig

       Fax:               (212) 893 2070

       and                Reuters SA
                          Rue Jargonnant 1
                          Geneva 01211, Switzerland

       For the attention of: Jean-Claude Marchand

       Fax:               (41) 22 718 2695

       and                Reuters America Inc.
                          1700 Broadway - 40th Floor
                          New York, New York  10019

       For the attention of: General Counsel

       Fax:               (212) 603 3757

(b)    AETHER OR AETHER PARENT:

       Address:           Aether Systems, Inc.
                          11460 Cronridge Drive
                          Owings Mills,
                          Maryland 21117

       For the attention of:      David S. Oros, Chief Executive Officer

       Tel:               (410) 654 6400

       Fax:               (410) 654 6554

       with a copy to:    Wilmer, Cutler & Pickering
                          2445 M Street, N.W.
                          Washington, D.C. 20037

       For the attention of:      Mark Dewire, Esq.

       Tel:               (202) 663 6000

       Fax:               (202) 663 6363

(c)    THE COMPANY:

                                                                         Page 38
<PAGE>   44

       Address:           Sila Communications Limited
                          4 Carlton Gardens
                          Pall Mall
                          London SW1Y 5AA

       For the attention of:      Bo Kroll, President

       Tel:               (020) 7872 1000

       Fax:               (020) 7839 3537

       with a copy to:    Wilmer, Cutler & Pickering
                          4 Carlton Gardens
                          Pall Mall
                          London SW1Y 5AA

       For the attention of:      Andrew Parnell, Esq.

       Tel:               (020) 7872 1000

       Fax:               (020) 7839 3537

ENGLISH LANGUAGE

26.3   All notices or formal communications under or in connection with this
Agreement shall be in the English language or, if in any other language,
accompanied by a translation into English. In the event of any conflict between
the English text and the text in any other language, the English text shall
prevail.

SETTLEMENT OF DISPUTES

27.1   In the event of any dispute arising in connection with this Agreement or
any Ancillary Agreements or documents referred to herein or therein, the parties
to such dispute shall use all reasonable endeavours to resolve the matter on an
amicable basis. If one party serves formal written notice on the other(s) that a
material dispute of such a description has arisen between them and the relevant
parties are unable to resolve the dispute within a period of twenty (20) days
from the service of such notice, then the dispute shall be referred to:

(a)    (if Aether or Aether Parent is a party) David Oros (for so long as he is
       an executive of Aether) or the Chief Executive Officer of Aether
       thereafter;

(b)    (if Reuters or Reuters Parent is a party) Devin Wenig (or his successor
       as the most senior executive in the Reuters Group who has had direct
       involvement with the Company);

                                                                         Page 39
<PAGE>   45

(c)    (if the Company is a party) David Oros (or his successor as the Chief
       Executive Officer of the Company; and

(d)    (if any party other than Aether, Aether Parent, Reuters, Reuters Parent
       or the Company is a party) a representative of similar authority as set
       forth in (a) through (c) above appointed by such party, or if multiple
       parties, appointed by the holder(s) of a majority of the Shares held by
       such parties.

No recourse to arbitration or Court proceedings by one party against any other
under this Agreement shall take place unless a period of not less than twenty
(20) days has expired after such referral. This shall not affect a party's
right, where appropriate, to seek an immediate remedy for an injunction,
specific performance or similar court order to enforce the obligations of
another party.

ARBITRATION

27.2   All disputes arising out of or in connection with this Agreement or any
Ancillary Agreement or documents referred to herein or therein (if unresolved by
the representatives thereof pursuant to clause 27.1) shall be referred to and
finally settled by arbitration under the Rules of Conciliation and Arbitration
of the International Chamber of Commerce by three arbitrators each appointed in
accordance with those Rules provided that each arbitrator shall be a national
of, a member of the European Union or the USA. The place of arbitration shall be
Paris, France. The language of arbitration proceedings shall be English.

COUNTERPARTS

28.    This Agreement may be executed in any number of counterparts and by the
principals to it on separate counterparts, each of which shall be an original
but all of which together shall constitute one and the same instrument.

NO RIGHTS UNDER CONTRACTS (RIGHTS OF THIRD PARTIES) ACT 1999

29.    A person who is not a principal to this Agreement shall have no right
under the Contracts (Rights of Third Parties) Act 1999 to enforce any of its
terms.

GOVERNING LAW

30.    This Agreement shall be governed by and construed in accordance with the
laws of England.

                                                                         Page 40
<PAGE>   46

AS WITNESS this Agreement has been signed by the duly authorised representatives
of the parties the day and year first before written.

                                                                         Page 41
<PAGE>   47

SIGNED by _______ _______ _______       )
for and on behalf of              )
REUTERS OVERSEAS                  )
HOLDINGS B.V.                     )

SIGNED by _______ _______ _______       )
for and on behalf of              )
REUTERS LIMITED                   )

SIGNED by _______ _______ _______       )
for and on behalf of              )
AETHER EUROPEAN                   )
HOLDINGS B.V.                     )

SIGNED by _______ _______ _______       )
for and on behalf of              )
AETHER SYSTEMS, INC.              )

SIGNED by _______ _______ _______       )
for and on behalf of              )
SILA COMMUNICATIONS               )
LIMITED                           )

                                                                         Page 42
<PAGE>   48

                                   SCHEDULE 1

                                     PART 1

                          RESERVED SHAREHOLDER MATTERS

       Articles
(a)    adopting or altering the Memorandum, Articles or other constitutional
       documents of the Company;

       changes in share capital
(b)    the issue of any shares by the Company ranking in priority to the Shares;

       dividends
(c)    the Company or any of its Subsidiaries (other than wholly-owned
       Subsidiaries) declaring or paying any dividend or distribution;

       winding-up
(d)    any proposal to wind up all or any significant portion of the Company's
       Group.

                                                                         Page 43
<PAGE>   49

                                     PART 2

                             RESERVED BOARD MATTERS

       change in nature of Business
(a)    materially changing the nature or scope of the business (as described in
       clause 2.1) of the Company's Group taken as a whole;

       borrowings
(b)    any member of the Company's Group borrowing or raising money which would
       lead to the Company's Group (on a consolidated basis) having aggregate
       indebtedness in excess of 20% of the fair value of the total assets of
       the Company's Group, as determined in good faith by the Board;

       transactions with Reuters Group or Aether Groups
(c)    any transaction by the Company or any of its Subsidiaries with either any
       of its directors, employees or other officers or any person/entity which
       has a Shareholding Proportion of at least 5 per cent., which is either:

         (i)  outside the ordinary course of business; or

        (ii)  within the ordinary course of business but has a value of more
              than pound sterling 100,000 or is not on commercial arm's length
              terms;

       acquisitions, disposals and mergers
(d)      (i)  the Company or any of its Subsidiaries acquiring, disposing of
              (whether in a single transaction or series of transactions) or
              creating any mortgage, charge, encumbrance or other security
              interest of any nature in respect of any business (or any material
              part of any business) or of any shares in any company where the
              value of the acquisition or disposal is greater than 20% of the
              fair value of the total assets of the Company's Group, as
              determined in good faith by the Board; or

        (ii)  any merger, consolidation, or amalgamation of the Company or any
              of its Subsidiaries;

       flotation
(e)    a Flotation of the Company or any of its Subsidiaries with net proceeds
       to the Company of less than pound sterling 15 million or a per share
       price which implies a valuation of the fully diluted share capital of the
       Company of at least pound sterling 187.5 million;

                                                                         Page 44
<PAGE>   50

       Accounting Principles
(f)    any change in the Accounting Principles.

                                                                         Page 45
<PAGE>   51

                                   SCHEDULE 2

                                DEED OF ADHERENCE

THIS DEED is made on -

BY [               ] of [                                     ] (the COVENANTOR)

WHEREAS:

(A)    On - the persons in the schedule hereto entered into a shareholders'
       agreement governing their relationship as shareholders in Sila
       Communications Limited (the COMPANY) and establishing the manner in which
       the affairs of the Company would be conducted (such agreement, as amended
       and/or novated, the SHAREHOLDERS' AGREEMENT).

(B)    The Covenantor wishes to become a party to the Shareholders' Agreement
       immediately upon acquiring certain shares in the Company and wishes to
       amend the Shareholders' Agreement with the effect that the Covenantor
       becomes a party thereto and as such assumes the rights and obligations as
       a principal, as defined in the Shareholders' Agreement.

NOW THIS DEED WITNESSES as follows:

1.     INTERPRETATION

Words and expressions defined in the Shareholders' Agreement shall, unless the
context otherwise requires, have the same meanings when used in this Deed.

2.     ADHERENCE

The Covenantor hereby covenants to and undertakes with each of the other persons
in the schedule to this Deed and with each such other person who may from time
to time expressly adhere to the Shareholders' Agreement (by way of execution of
a deed or by way of novation) to be bound by and comply in all respects with the
Shareholders' Agreement, and to assume the benefits of the Shareholders'
Agreement, as if the Covenantor had executed the Shareholders' Agreement as a
principal and was named as an original party thereto.

3.     NOTICES

For the purpose of the Shareholders' Agreement, the Covenantor's address for
notices shall be as follows:

                                                                         Page 46
<PAGE>   52

Address:

Fax No:

Addressed for the personal attention of:

4.     GOVERNING LAW

This Deed shall be governed by and construed in accordance with English law.

Duly delivered as a Deed on the date inserted above.

                                                                         Page 47
<PAGE>   53

                                    SCHEDULE

                     PARTIES TO THE SHAREHOLDERS' AGREEMENT

1.     Reuters Overseas Holdings B.V.

2.     Aether European Holdings B.V.

3.     Sila Communications Limited

4.     Reuters Limited

5.     Aether Systems, Inc.

                                                                         Page 48
<PAGE>   54

EXECUTED as a DEED by             )
[                      ]    )
acting by two Directors/    )
a Director and the Secretary)

                                                                         Page 49
<PAGE>   55

                                   SCHEDULE 3

                              ACCOUNTING PRINCIPLES

ACCOUNTING BASES

The financial statements are prepared under the historical cost convention and
in accordance with applicable accounting standards.

BASIS OF CONSOLIDATION

The consolidated financial statements include:

(a)    The financial statements of the Company and any subsidiaries to 31
       December. The results of any subsidiaries are included for the period
       during which they are a member of the group.

(b)    The Company's share of the post-acquisition results of associated
       undertakings and joint ventures. Investments in associated undertakings
       and joint ventures are included at the Company's share of the net assets
       at the dates of acquisition plus the group's share of post-acquisition
       reserves.

FOREIGN CURRENCY TRANSLATION

Where it is considered that the functional currency of an operation is sterling
the financial statements are expressed in sterling on the following basis:

(a)    Fixed assets are translated into sterling at the rates ruling on the date
       of acquisition as adjusted for any profits or losses from related
       financial instruments.

(b)    Monetary assets and liabilities denominated in a foreign currency are
       translated into sterling at the foreign exchange rates ruling at the
       balance sheet date.

(c)    Revenue and expenses in foreign currencies are recorded in sterling at
       the rates ruling for the month of the transactions.

(d)    Any gains or losses arising on translation are reported as part of
       profit.

For other operations, associated undertakings and joint ventures, assets and
liabilities are translated into sterling at the rates ruling at the balance
sheet date. Revenue and expenses in foreign currencies are recorded in sterling
at the rates ruling for the month of the transactions

                                                                         Page 50
<PAGE>   56

and gains or losses arising on translation are dealt with through reserves.

TREASURY

The Company receives revenue and incurs expenses in more than 13 currencies and
uses financial instruments to hedge a portion of its net cash flow and operating
profit. Profits and losses from hedging activities are matched with the
underlying cash flows and profits being hedged. Those relating to trading cash
flows are reported as part of profit and those relating to the Company's capital
expenditure programme are adjusted against the cost of the assets to which they
relate.

The Company uses financial instruments to hedge a portion of its interest
exposure. Profits and losses on financial instruments are reported as part of
profit for the period to which they relate.

Financial instruments hedging the risk on foreign currency assets are revalued
at the balance sheet date and the resulting gain or loss offset against that
arising from the translation of the underlying asset into sterling.

REVENUE

Revenue represents the turnover, net of discounts, derived from services
provided to subscribers and sales of equipment applicable to the year.
Short-term contracts are accounted for on a completed contract basis.

DEVELOPMENT

Development expenditure is charged against profit in the year in which it is
incurred.

PENSIONS AND SIMILAR OBLIGATIONS

The expected cost of pensions and other post-retirement benefits is charged
against profit so as to spread the cost over the service lives of the employees
affected.

TANGIBLE FIXED ASSETS

Depreciation is calculated on a straight line basis so as to write down the
assets to their residual values over their expected useful lives:

<TABLE>
<S>                               <C>
Freehold land                     Not depreciated

Freehold buildings                Normally 50 years
</TABLE>

                                                                         Page 51
<PAGE>   57

<TABLE>
<S>                               <C>
Leasehold property                Over the term of the lease

Computer systems                  3 to 5 years
equipment, office
equipment and motor
vehicles
</TABLE>

STOCKS

Stocks and contract work in progress are valued at the lower of costs and net
realisable value less progress payments received and receivable from clients.
Progress payments in excess of the value of work carried out are included within
creditors.

Cost is calculated on a first in first out basis by reference to the invoiced
value of supplies and attributable costs of bringing stocks to their present
location and condition.

Net realisable value is the estimated market value less selling costs.

SHORT-TERM INVESTMENTS

Government securities are stated in the balance sheet at the lower of cost plus
accrued capital appreciation and market value. Income from these securities and
any adjustment for changes in their market value during the year are reported as
part of profit.

Interest on certificates of deposit is calculated at the yield at which the
certificate was purchased and is reported as part of profit over the life of the
certificate. Certificates of deposit are stated in the balance sheet at the
lower of costs plus accrued interest and market value.

Movements in short-term investments are reported under the heading of management
of liquid resources in the cash flow statement.

DEBT ISSUANCE

Medium-term notes and commercial paper are stated at the amount of the net
proceeds plus any accrued interest or discount. Discounts or premia to the
nominal value are amortised over the term of the issue. Costs associated with
debt issuance are charged against profit over the life of the instrument.

Foreign currency swap agreements and forward contracts are used to convert
non-sterling debt into sterling. Interest rate swaps, swaptions and forward rate
agreements are used to manage interest rate exposures. Amounts payable or
receivable in respect of these derivatives are

                                                                         Page 52
<PAGE>   58

recognised as adjustments to interest expense over the period of the contract.

LEASING

Assets acquired under a finance lease are recorded in the balance sheet as
tangible fixed assets with corresponding obligations to pay future rentals. The
assets are valued at the present value of the minimum lease payments at the rate
implicit in the lease.

Rentals payable are apportioned between a finance charge and a reduction of the
outstanding obligation for future amounts payable. The total finance charge is
allocated to accounting periods during the lease term so as to produce a
constant periodic rate of charge on the outstanding obligation throughout the
lease.

Operating lease rentals are charged against profit on a straight line basis over
the period of the lease.

DEFERRED TAXATION

Tax deferred or accelerated by the effect of timing differences is accounted for
to the extent that it is considered probable that a liability or asset will
crystallise in the foreseeable future. The only exception to this is in respect
of deferred tax assets relating to provisions for pensions and other
post-retirement benefits which are recognised in full.

GOODWILL AND INTANGIBLE ASSETS

Purchased goodwill and intangible assets are capitalised and amortised through
the profit and loss account over their estimated lives which are between five
and 20 years.

                                                                         Page 53
<PAGE>   59

                                   SCHEDULE 4

                     MEMORANDUM AND ARTICLES OF THE COMPANY

                                                                         Page 54<PAGE>   1
                                                                  EXECUTION COPY

                           MEMORANDUM OF UNDERSTANDING

            This Memorandum of Understanding ("MOU") is entered into as of this
3rd day of August, 2000 by and among Teleglobe Inc. ("TELEGLOBE"), Teleglobe
Mobile Partners ("TMP"), Orbital Sciences Corporation ("ORBITAL"), Orbital
Communications Corporation ("OCC") and ORBCOMM Global, L.P. ("ORBCOMM").

            WHEREAS, ORBCOMM is engaged in the business of constructing,
operating and marketing a satellite communications system of low-Earth orbit
satellites intended to provide data communications services throughout the world
(the "ORBCOMM SYSTEM");

            WHEREAS, the ORBCOMM System is in commercial service but has not yet
achieved sufficient cash flow to enable it to fund its continuing operations;

            WHEREAS, Teleglobe has been providing capital to ORBCOMM through its
indirect wholly owned subsidiary, TMP, the sole general partner of ORBCOMM, to
fund ORBCOMM's operations;

            WHEREAS, Teleglobe has advised ORBCOMM that it is no longer in a
position to continue to provide equity capital to ORBCOMM;

            WHEREAS, efforts by Teleglobe, TMP, Orbital, OCC and ORBCOMM to
obtain alternative sources of equity funding for ORBCOMM over the past several
months have not yet been successful; and

            WHEREAS, the parties have been engaged in active discussions
concerning how to maintain ORBCOMM's business and preserve the value of the
ORBCOMM System pending receipt of a new equity investment and/or a sale of
ORBCOMM.

            NOW, THEREFORE, in consideration of the foregoing and of the mutual
covenants and agreements hereinafter set forth, the parties hereto hereby
memorialize their mutual understandings as follows:

            1. Business Plan. ORBCOMM, in consultation with Teleglobe and
Orbital, has developed a plan for the ORBCOMM business that contemplates the
continued operation of all critical functions relating to the ORBCOMM System,
the substantial reduction of costs associated with noncore operations and the
termination of nonessential aspects of the business. A copy of such plan (the
"BUSINESS PLAN") is attached hereto as EXHIBIT A. ORBCOMM will devote its
commercially reasonable efforts to the prompt and successful implementation of
the Business Plan, subject to such reasonable
<PAGE>   2
modifications as may hereafter be developed by ORBCOMM in consultation with and
with prior approval from Teleglobe and Orbital.

            2. Restructuring Arrangements.

               (a) Orbital agrees to continue actively to pursue discussions
with potential investors in ORBCOMM. Orbital further agrees to consider
facilitating the infusion of additional equity into ORBCOMM by issuing a
security of Orbital that would be convertible into an equity interest in
ORBCOMM, with the proceeds of such issuance to be directed to ORBCOMM. Teleglobe
and ORBCOMM agree to support such efforts by Orbital and to cooperate with
Orbital in order to obtain such new equity investment as promptly as
practicable. The parties will endeavor to close a transaction with a new equity
investor on or before September 15, 2000.

               (b) ORBCOMM agrees to work with its creditors to restructure its
debt in a manner consistent with the Business Plan and with the objectives of
any potential new equity investor. In connection therewith, ORBCOMM will (i)
after consultation with Teleglobe and Orbital, engage such investment bankers
and/or other professional advisers/managers as may be appropriate to assist
ORBCOMM in implementing the Business Plan and restructuring its indebtedness,
and (ii) take such other steps as may be appropriate to prepare for an orderly
filing under Chapter 11 of the United States Bankruptcy Code, if necessary, with
the objective of minimizing disruption to the ORBCOMM business. ORBCOMM and
Orbital agree that such a filing may be made at Teleglobe's sole election;
provided that prior to any such filing ORBCOMM shall have received the Interim
Financing (as defined below) and expended such financing substantially in
accordance with the Business Plan.

            3. Teleglobe Financing Arrangements.

               (a) Commencing immediately, Teleglobe will provide or cause to be
provided an aggregate of $17 million of debt financing to ORBCOMM as follows:
interim debt financing, which may be secured consistent with the existing
contractual obligations of ORBCOMM (the "INTERIM FINANCING"), to enable ORBCOMM
to meet payroll, severance, employee benefits, withholding taxes, rent,
utilities and other obligations integral to ORBCOMM's continuing operations in
accordance with the Business Plan, and to pay expenses incurred in preparation
for a potential Chapter 11 filing; and continuing reorganization financing (the
"REORGANIZATION FINANCING"), which may, at Teleglobe's discretion, take the form
of debtor-in-possession financing ("DIP FINANCING"), subject to Bankruptcy Court
approval. (The Interim Financing and the Reorganization Financing are sometimes
hereinafter collectively called the "TELEGLOBE FINANCING".) The Interim
Financing shall be in an aggregate amount of $8 million and shall be provided
under a Bridge

                                       2
<PAGE>   3
Credit Agreement substantially in the form attached hereto as EXHIBIT B, under
which ORBCOMM shall be entitled to receive an immediate drawing/advance of
$4,950,000 to be used consistent with the funding requirements identified in the
Business Plan. The remaining amount of $3,050,000 (the "SECOND ADVANCE") shall
be advanced on the business day immediately following the receipt by ORBCOMM of
a fairness opinion relating to the Interim Financing pursuant to the terms of
the Indenture governing the outstanding senior notes of ORBCOMM, with the only
condition to such Second Advance being the receipt of such fairness opinion. The
Reorganization Financing shall be advanced from time to time upon the request of
ORBCOMM consistent with the Business Plan and applicable Bankruptcy Court orders
(if the Reorganization Financing takes the form of DIP Financing), all pursuant
to loan, security and other legal documentation reasonably satisfactory in form
and substance to Teleglobe.

               (b) Teleglobe agrees that, notwithstanding any priority to which
it would otherwise be entitled, Teleglobe will, in conjunction with a
restructuring of ORBCOMM that includes receipt of a new equity infusion and
conversion to equity of all of ORBCOMM's obligations under its procurement
agreements with Orbital, convert or cause to be converted both the Interim
Financing and the Reorganization Financing into ORBCOMM equity, subject to
paragraph 5(b) below; provided, that Teleglobe reserves all of its rights in
respect of recovery of the Interim Financing and Reorganization Financing in
connection with any other restructuring/reorganization (i.e., a sale) of
ORBCOMM.

            4. Dismissal of Teleglobe/BCE Inc. lawsuits. At such time as
Teleglobe has fully funded the $17 million of Teleglobe Financing, Orbital
agrees (a) to dismiss with prejudice the lawsuit filed on June 27, 2000 in the
United States District Court for the Eastern District of Virginia against
Teleglobe and BCE Inc. (the "VIRGINIA ACTION"), (b) to withdraw the demand
letter sent to Teleglobe on June 8, 2000 demanding payment of certain amounts
owing to Orbital under the procurement agreements and (c) to join with
Teleglobe, TMP and OCC in exchanging appropriate mutual releases covering the
claims asserted by Orbital in such demand letter and any similar claims of
Teleglobe or TMP against Orbital or OCC. Pending such dismissal, withdrawal and
exchange of releases (and subject to (A) continuing compliance by Teleglobe and
TMP with the terms of this MOU and (B) the full funding of the Interim Financing
on or before August 15, 2000), (i) neither Orbital nor OCC will take any action
to prosecute the Virginia Action (except that they may, if necessary to preserve
the action, effect service of the Complaint on Teleglobe) or pursue the claims
asserted in the aforementioned demand letter; and (ii) to the extent necessary
to relieve Teleglobe and BCE Inc. from any obligation to file responsive
pleadings in the Virginia Action, Orbital and OCC shall consent to extensions of
time or shall, if necessary, dismiss the Virginia Action without prejudice,
subject, if Orbital and OCC so request, to execution

                                       3
<PAGE>   4
by Teleglobe and BCE Inc. of an appropriate tolling agreement extending any and
all limitations periods otherwise applicable to any of the claims asserted in
the Virginia Action.

            5. Implementation of Plan of Reorganization.

               (a) Orbital agrees, in conjunction with the reorganization of
ORBCOMM, (i) to make itself available to serve on ORBCOMM's unsecured creditors'
committee and (ii) if the restructuring/reorganization of ORBCOMM provides for a
new equity infusion (as opposed to a sale of the business), to convert all of
its claims whatsoever against ORBCOMM under Orbital's procurement agreements
with ORBCOMM into equity of the reorganized ORBCOMM.

               (b) Effective upon the implementation of any
restructuring/reorganization plan that provides for conversion of Orbital and
Teleglobe/TMP claims to equity in conjunction with an infusion of additional
equity, as contemplated in paragraphs 3(b) and 5(a), Orbital and Teleglobe will
adjust their equity allocations so that of the combined equity in the
reorganized ORBCOMM received by Orbital upon conversion of its procurement
agreement claims and received by Teleglobe/TMP upon conversion of the Teleglobe
Financing (whatever the level of that combined equity), Orbital will have 60%
and Teleglobe/TMP 40%; provided that Teleglobe/TMP will have no obligation to be
more than a passive investor in the reorganized company, and further provided
that the equity interest in the reorganized ORBCOMM received by Teleglobe/TMP
upon conversion of the Teleglobe Financing shall correspond in all other
respects to the equity interest received by Orbital upon conversion of its
procurement agreement claims.

            6. Employee Retention. ORBCOMM, in consultation with Orbital and
Teleglobe, agrees to take such actions as are reasonably necessary to retain and
motivate key ORBCOMM employees, which may include the establishment of an
ORBCOMM employee stock option plan.

            7. Miscellaneous.

               (a) SUCCESSORS AND ASSIGNS. This MOU and the rights and
obligations set forth herein shall not be assignable by the parties. The
provisions of this MOU shall, except as otherwise provided herein, enure to the
benefit of and be binding upon the parties and their respective successors and
each and every person so bound shall make, execute and deliver all documents
necessary to carry out this MOU.

               (b) PUBLIC ANNOUNCEMENT. Except as provided herein or as required
by law, no press release related to this MOU or the transactions contemplated
herein shall be issued without the joint approval of Teleglobe and Orbital.

                                       4
<PAGE>   5
               (c) FURTHER ASSURANCES. Each party shall do such acts and shall
execute such further documents as are within its power as any other party may in
writing at any time and from time to time reasonably request be done or
executed, in order to give full effect to the provisions of this MOU.

               (d) REQUIREMENT OF DEFINITIVE DOCUMENTATION. Each of the parties
hereto agrees that the provisions of Paragraphs 2, 3, 4, 5, and 6 of this MOU do
not contain all material terms that must be agreed upon in order to implement
the arrangements contemplated by such paragraphs and are therefore subject to
the preparation, negotiation and execution of definitive agreements and
documents. Each of the parties hereto agrees to negotiate such definitive
agreements and documents in good faith. This MOU provides the basis upon which
the parties shall negotiate the terms of definitive agreements and documents;
but to the extent that such definitive agreements and documents may be
inconsistent with this MOU, the terms of such definitive agreements and
documents shall take priority.

               (e) GOVERNING LAW. This MOU shall be governed by and construed in
accordance with the laws of the Commonwealth of Virginia (but not including the
choice-of-law rules thereof).

               (f) LIMITATION ON BENEFITS. Paragraphs 3(b), 4 and 5 of this MOU
are solely for the benefit of Teleglobe and Orbital and their respective
affiliates, excepting ORBCOMM. Other than as set forth in Paragraph 4 with
respect to BCE Inc., no third party is entitled to the benefit of any of the
promises made herein or entitled to enforce such provisions against Orbital and
its affiliates or Teleglobe and its affiliates.

               (g) COUNTERPARTS. This MOU may be executed in one or more
counterparts each of which when so executed shall be deemed to be an original
and such counterparts together shall constitute one and the same instrument.

                                       5
<PAGE>   6
               (h) IN WITNESS WHEREOF the parties have executed this Memorandum
of Understanding as of the date set out above.

                                    ORBITAL SCIENCES CORPORATION

                                    By:  _____________________________________
                                    Name:  ___________________________________
                                    Title:  __________________________________

                                    ORBITAL COMMUNICATIONS CORPORATION

                                    By:  _____________________________________
                                    Name:  ___________________________________
                                    Title:  __________________________________

                                    TELEGLOBE INC.

                                    By:  _____________________________________
                                         Andre Bourbonnais
                                         Executive Vice President, Chief Legal
                                         Officer and Corporate Secretary

                                    TELEGLOBE MOBILE PARTNERS,
                                    by its General Partner
                                    TELEGLOBE MOBILE INVESTMENT INC.

                                    By:  _____________________________________
                                         Andre Bourbonnais
                                         President

                                    ORBCOMM GLOBAL, L.P.

                                    By:  ____________________________________
                                         Scott Webster
                                         President, Chief Executive Officer

                                       6

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