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                                                                    EXHIBIT 4.2



                             SUBSCRIPTION AGREEMENT

                               DATED AS OF --, 1998

                                 BY AND BETWEEN

                               ORBCOMM CORPORATION

                                       AND

                              ORBCOMM GLOBAL, L.P.


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                        This SUBSCRIPTION AGREEMENT  (this  "Agreement")  is
dated as of --, 1998 and is by and between ORBCOMM Corporation, a Delaware
corporation (the "Company"), and ORBCOMM Global, L.P. ("ORBCOMM"), a Delaware
limited partnership.

                        WHEREAS, the Company intends to consummate an
underwritten initial public offering (the "Offering") of 6,000,000 shares of its
Common Stock, par value $.01 per share (the "Common Stock") (6,900,000 shares if
the Underwriters' over-allotment option is exercised in full) and to use the
proceeds of the Offering to purchase an equivalent number of Partnership Units
("Units") in ORBCOMM as described in the registration statement on Form S-1
(File No. 333-50599) filed with the U.S. Securities and Exchange Commission, as
amended (the "Registration Statement").

                        WHEREAS, upon consummation of the Offering, ORBCOMM
intends to issue and sell to the Company  6,000,000 Units (6,900,000 Units if
the Underwriters' over-allotment option is exercised in full) at a purchase
price per Unit equal to the per share public offering price of the Common Stock
less the per share underwriting discount.

                        WHEREAS, ORBCOMM owns all 100 currently outstanding
shares of Common Stock (the "Outstanding Shares") and intends to surrender the
Outstanding Shares to the Company in connection with the consummation of the
Offerings and the Company intends to cancel the Outstanding Shares upon
surrender by ORBCOMM.

                        NOW, THEREFORE, the parties hereto, intending to be
bound, hereby agree as follows:

                                   ARTICLE I.
                                   DEFINITIONS

                        SECTION 1.1.  REFERENCE TO REGISTRATION STATEMENT.
Capitalized terms used but not defined herein shall have the meanings assigned
to such terms in the Registration Statement.

                        SECTION 1.2.  CERTAIN DEFINITIONS.  As used in this
Agreement, the following terms have the following respective meanings:

                        "AGREEMENT" means this Subscription Agreement.

                        "COMMON STOCK" has the meaning assigned to the term in
the recitals of this Agreement.

                         "FIRM UNITS" has the meaning assigned to the term in
Section 2.1 of this Agreement.

                        "FIRM SHARES" means the shares of Common Stock
purchased by the Underwriters pursuant to the Underwriting Agreement without
giving effect to the exercise of the over-allotment option.

                        "ORBCOMM" means the Partnership as such term is used in
the Partnership Agreement referenced herein.

                         "OFFERING" has the meaning assigned to the term in the
recitals of this Agreement.

                        "OPTION UNITS" has the meaning assigned to the term in
Section 2.2 of this Agreement.

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                        "OPTION SHARES" means the shares of Common Stock
purchased by the Underwriters pursuant to the over-allotment option granted in
the Underwriting Agreement.

                        "PARTNERSHIP AGREEMENT" means the Limited Partnership
Agreement of ORBCOMM Global, L.P. dated as of --, as amended.

                        "REGISTRATION STATEMENT" has the meaning assigned to
the term in the recitals of this Agreement.

                        "UNITS" has the meaning assigned to the term in the
recitals of this Agreement.

                                   ARTICLE II.
                        PURCHASE OF UNITS BY THE COMPANY

                        SECTION 2.1.  FIRM UNITS.  Subject to the terms and
conditions set forth herein, ORBCOMM agrees to create, issue and sell 6,000,000
Units to the Company (the "FIRM UNITS") and the Company agrees to purchase the
Firm Units at a price per Firm Unit equal to the per share price paid by the
Underwriters for the 6,000,000 Firm Shares of Common Stock purchased by the
Underwriters pursuant to the Underwriting Agreement.

                        SECTION 2.2.  OVER-ALLOTMENT UNITS.  Subject to terms
and conditions set forth herein, ORBCOMM agrees to create, issue and sell up to
900,000 Units to the Company (the "OPTION UNITS") and the Company agrees to
purchase an aggregate number of Option Units that is equal to the number of
Option Shares of Common Stock purchased by the Underwriters pursuant to the
Purchase Agreement at a price per Option Unit equal to the price paid by the
Underwriters for the Option Shares of Common Stock purchased by the
Underwriters pursuant to the Purchase Agreement.

                                  ARTICLE III.
                       DELIVERY AND PAYMENT FOR INTERESTS

                        SECTION 3.1.  DELIVERY OF AND PAYMENT FOR FIRM UNITS.
Delivery of certificates for the Firm Units shall be made at the time and
location of the delivery of the Firm Shares under the Purchase Agreement
against payment of the purchase price therefor in immediately available funds.

                        SECTION 3.2.  DELIVERY OF AND PAYMENT FOR OPTION UNITS.
Delivery of certificates for the Option Units shall be made at the time and
location of the delivery of the Option Shares under the Purchase Agreement
against payment of the purchase price therefor in immediately available funds.

                        SECTION 3.3.  DELIVERY AND CANCELLATION OF
OUTSTANDING SHARES.  ORBCOMM hereby agrees that in addition to its other
obligations under this Agreement, upon payment by the Company of the purchase
price for the Firm Shares pursuant to Section 3.1 above, ORBCOMM shall deliver
the Outstanding Shares to the Company and shall relinquish any rights in or
claims on the Outstanding Shares. The Company hereby agrees that upon delivery
of the Outstanding Shares by ORBCOMM, the Company shall retire and cancel such
Outstanding Shares.

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                                   ARTICLE IV.
                       ADMISSION OF THE COMPANY TO ORBCOMM

                        SECTION 4.1.  ADMISSION OF THE COMPANY.  The Company
wishes to be admitted as a General Partner in ORBCOMM and agrees to be bound by
all of the applicable provisions of the Partnership Agreement. Prior to the
first issuance of any Units hereunder, the Company will execute and deliver a
counterpart of the Partnership Agreement in substantially the form set forth in
Annex A hereto. This Agreement constitutes the Company's written request that
ORBCOMM's Partnership Unit Register be amended to reflect the Company's
admission as a General Partner and ORBCOMM agrees that its Partnership Unit
Register will be so amended, and the Company will be admitted as a General
Partner in ORBCOMM, on the date of the issuance of the Firm Units hereunder.

                                   ARTICLE V.
                            EXPENSES OF THE OFFERING

                        The Company shall pay for all expenses incurred by the
Company in connection with the Offering and the transactions contemplated by
this Agreement.

                                   ARTICLE VI.
                     CONDITIONS OF THE PARTIES' OBLIGATIONS

                        SECTION 6.1.  FIRM UNITS.  The respective obligations
of the parties with respect to the Firm Units are subject to the performance by
the Underwriters of their obligations to purchase the Firm Shares under the
Purchase Agreement.

                        SECTION 6.2.  OPTION UNITS.  The respective obligations
of the parties with respect to the Option Units, if any, are subject to the
performance by the Underwriters of their obligations, if any, to purchase
Option Shares under the Purchase Agreement.

                                  ARTICLE VII.
                         REPRESENTATIONS AND WARRANTIES

                        SECTION 7.1.  REPRESENTATIONS AND WARRANTIES OF
ORBCOMM.  ORBCOMM hereby represents and warrants that it has duly and validly
executed and delivered this Agreement and that the Firm Units and the Option
Units, if any, when issued against payment therefore by the Company pursuant to
Article III, will be duly and validly authorized and issued and fully-paid and
non-assessable.

                        SECTION 7.2.  REPRESENTATIONS AND WARRANTIES OF THE
COMPANY.  The Company hereby represents and warrants that it has duly and
validly executed and delivered this Agreement and will duly and validly execute
the Partnership Agreement pursuant to Article IV.

                                  ARTICLE VIII.
                        INDEMNIFICATION AND CONTRIBUTION

                        SECTION 8.1.  INDEMNIFICATION BY ORBCOMM. ORBCOMM will
indemnify and hold harmless the Company and each of its officers, directors and
employees (each an "INDEMNIFIED PARTY") against any losses, claims, damages or
liabilities to which such indemnified party may become subject, under the
Securities Act or otherwise, that directly or indirectly, arise out of or are
related to, the transactions contemplated by this Agreement, and will reimburse
such indemnified party for any legal or other expenses reasonably incurred by
such indemnified party in connection with investigating or

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defending any such action or claim, as such losses, damages, liabilities or
expenses are incurred; provided, however, that ORBCOMM shall not be liable in
any such case to any indemnified party to the extent that any such loss, claim,
damage or liability arises out of or is based upon an intentional act or
omission of the indemnified party that was contrary to any written instruction
or request of ORBCOMM or that amounted to willful misconduct on the part of the
indemnified party.

                        SECTION 8.2.  PROCEEDINGS.  Promptly after receipt by
an indemnified party of notice of the commencement of any action, suit or
proceeding as to which a claim in respect thereof is to be made against ORBCOMM
under Section 8.1, the indemnified party shall notify ORBCOMM in writing of the
commencement thereof, but the omission so to notify ORBCOMM shall not relieve
ORBCOMM from any liability which it may have to any indemnified party otherwise
than under such section, unless ORBCOMM is materially prejudiced thereby. In
case any such action shall be brought against any indemnified party and it
shall notify ORBCOMM of the commencement thereof, ORBCOMM shall be entitled to
participate therein and, to the extent that it shall wish, to assume the
defense thereof, with counsel reasonably satisfactory to such indemnified
party, and, after notice from ORBCOMM to such indemnified party of its election
so to assume the defense thereof, ORBCOMM shall not be liable to such
indemnified party under such subsection for any legal expenses of other counsel
or any other expenses, in each case subsequently incurred by such indemnified
party, in connection with the defense thereof other than reasonable costs of
investigation. ORBCOMM shall not, without the written consent of the
indemnified party, effect the settlement or compromise of, or consent to the
entry of any judgment with respect to, any pending or threatened action or
claim in respect of which indemnification or contribution may be sought
hereunder (whether or not the indemnified party is an actual or potential party
to such action or claim) unless such settlement, compromise or judgment (a)
includes an unconditional release of the indemnified party from all liability
arising out of such action or claim and (b) does not include a statement as to
or an admission of fault, culpability or a failure to act, by or on behalf of
any indemnified party. No indemnified party shall effect the settlement or
compromise of, or consent to the entry of any judgment with respect to, any
pending or threatened action or claim in respect of which indemnification or
contribution has been or may be sought hereunder without the prior written
consent of ORBCOMM.

                        SECTION 8.3.  CONTRIBUTION.  To provide for just and
equitable contribution in circumstances in which the indemnity provided for in
Section 8.1 is for any reason held to be unenforceable although applicable in
accordance with its terms, ORBCOMM shall contribute to the losses, liabilities,
claims, damages and expenses of the type contemplated by such indemnity
agreement incurred by any indemnified party in such proportion as shall be
appropriate to reflect (a) the relative benefits received, directly or
indirectly, by ORBCOMM on the one hand and the indemnified party on the other
hand, from (i) the sale of the Firm Shares and the Option Shares, if any, and
(ii) the sale of the Firm Units and the Option Units, if any, and (b) the
relative fault of ORBCOMM on the one hand and the indemnified party on the
other, with respect to the acts or omissions that resulted in such loss,
liability, claim, damage or expense, or action in respect thereof, as well as
any other relevant equitable considerations. Each of ORBCOMM and the Company
agrees that it would not be just and equitable if contribution pursuant to this
Section 8.3 were to be determined by pro rata allocation or by any other method
of allocation that does not take into account the relevant equitable
considerations. No person guilty of fraudulent misrepresentation (within the
meaning of Section 11(f) of the Securities Act) shall be entitled to
contribution from ORBCOMM if ORBCOMM was not guilty of such fraudulent
misrepresentation.

                        The indemnity and contribution obligations in this
Article VIII are solely obligations of ORBCOMM and no recourse may be had
thereunder against any partner, partner representative, director, officer,
employee or agent of ORBCOMM.

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                                   ARTICLE IX.
                            MISCELLANEOUS PROVISIONS

                        SECTION 9.1.  GOVERNING LAW. This Agreement is governed
by, and shall be construed in accordance with, the laws of the State of New
York without regard to principles of conflicts of laws.

                        SECTION 9.2.  COUNTERPARTS.  This Agreement may be
executed in two or more counterparts, each of which shall be deemed an
original, but all of which together shall constitute one and the same
instrument.

                        SECTION 9.3.  ENTIRE AGREEMENT.  This Agreement
constitutes the entire understanding of the parties hereto with respect to the
subject matter hereof and supersedes all prior understandings among such
parties with respect to such subject matter.

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                        IN WITNESS WHEREOF, the parties have executed this
Agreement as of the day and year first above written.





                            ORBCOMM CORPORATION

                            ---------------------------
                            Name:  Scott L. Webster
                            Title: President and Chief Executive Officer



                            ORBCOMM GLOBAL, L.P.


                            ---------------------------
                            Name:  Scott L. Webster
                            Title: Chief Executive Officer


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                                     ANNEX A
                         TO 1998 SUBSCRIPTION AGREEMENT
                  FORM OF COUNTERPART TO PARTNERSHIP AGREEMENT


                        The undersigned agrees to be bound by the Partnership
Agreement of ORBCOMM Global, L.P., dated as of --, as amended, to which this
signature page is attached.

                                    IN WITNESS WHEREOF, the undersigned has
hereunto set its hand as of this -- day of March, 1998.

                                               GENERAL PARTNER
                                               ORBCOMM CORPORATION


                                               ---------------------------
                                               Name:
                                               Title:

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