1 EXHIBIT 4.5 Bear Stearns & Co. Inc. 245 Park Avenue New York, New York 10167 and J.P. Morgan Securities Inc. 60 Wall Street New York, New York 10260 As representatives of the several Underwriters named in Schedule I to the Underwriting Agreement referred to below Ladies and Gentlemen: The undersigned holds the position(s) set forth opposite his or her name on the attached Schedule A. The undersigned understands that ORBCOMM Corporation (the "Company") has filed a registration statement on Form S-1 (Reg. No. 333-50599) with the Securities and Exchange Commission covering the sale of up to 6,900,000 shares (the "Shares") of the Company's Common Stock, par value $.01 per share (the "Common Stock"), including shares subject to over-allotment options, to the Underwriters (the "Underwriters") named in Schedule I to the Underwriting Agreement (the "Underwriting Agreement"). The Underwriters propose to offer such Shares to the public (the "Offering"). This letter is being delivered pursuant to Section 6(i) of the Underwriting Agreement. All capitalized terms used but not defined herein shall have the meanings assigned to such terms in the Underwriting Agreement. To induce the Underwriters to participate in the Offering, the undersigned represents and warrants to, and agrees with, each of the Underwriters that during the period beginning on the date hereof and continuing to and including the date that is 180 days after the date of the Prospectus, the undersigned will not, without the prior written consent of Bear Stearns & Co. Inc. and J.P. Morgan Securities Inc., directly or indirectly, offer, sell, offer or agree to sell, grant any option for or otherwise dispose of (or announce any sale, offer, grant of an option to purchase or other disposition of) any shares of Common Stock (or any securities convertible into or exercisable or exchangeable for shares of Common Stock). 2 The undersigned has not taken and will not take, directly or indirectly, any action which is designed to or which has constituted or which might reasonably be expected to cause or result in stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Shares. This letter may be relied upon by the Underwriters. ---------------------------------------- Name: 3 Schedule A Scott L. Webster President, Chief Executive Officer and Director of ORBCOMM Corporation (the "Company") Chairman, Chief Executive Officer and Member of ORBCOMM Global, L.P. ("ORBCOMM") President and Director of Orbital Communications Corporation ("OCC") W. Bartlett Snell Chief Financial Officer and Treasurer of the Company Senior Vice President Finance and Administration, Chief Financial Officer and Treasurer of ORBCOMM Marc Leroux Director of the Company Member of ORBCOMM Vice President, Technology of Teleglobe Inc. ("Teleglobe") William J. Meder Director of the Company Vice Chairman and Member of ORBCOMM Jeffrey V. Pirone Director of the Company Member of ORBCOMM Executive Vice President and Chief Financial Officer of Orbital Sciences Corporation ("Orbital") Vice President and Chief Financial Officer of OCC Claude Seguin Executive Vice President, Finance and Chief Financial Officer of Teleglobe David W. Thompson Director of the Company Member of ORBCOMM Chairman of the Board, President and Chief Executive Officer of Orbital Director of OCC James R. Thompson, Jr. Executive Vice President and General Manager/Launch Systems Group of Orbital 4 Robert D. Strain Executive Vice President and General Manager/Electronics and Sensor Systems Group of Orbital Michael D. Griffin Executive Vice President and Chief Technical Officer of Orbital Daniel D. Friedmann Executive Vice President and General Manager/Systems Integration Group of Orbital Charles M. Boesenberg Executive Vice President and General Manager/Satellite Access Products Group of Orbital Robert R. Lovell Executive Vice President and General Manager/Space Systems Group of Orbital Antonio L. Elias Senior Vice President, Advanced Programs of Orbital Leslie C. Seeman Senior Vice President, General Counsel and Secretary of Orbital Alan Parker Executive Vice President of OCC Wan Aishah Wan Hamid Director of the Company Member of ORBCOMM Executive Vice President of Technology Resources Industries Bhd. Charles Sirois Chairman of the Board and Chief Executive Officer of Teleglobe Andre Bourbonnais Vice-President, Legal Affairs and Corporate Secretary of Teleglobe Meriel V.M. Bradford Vice-President, Governmental and External Relations of Teleglobe Jacques Deforges Treasurer of Teleglobe 5 Paolo Guidi President and Chief Executive Officer, Global Telecommunications Services of Teleglobe Fransois Laurin Vice-President, Finance and Corporate Controller of Teleglobe Fransois Gauvin Assistant Corporate Secretary of Teleglobe Guthrie J. Stewart Executive Vice President, Corporate Development of Teleglobe