CONSULTING AGREEMENT

Exhibit 10.18

CONSULTING AGREEMENT

This AGREEMENT is made and entered into November 8, 2003 (this “Agreement”) by and between Arbinet-thexchange, Inc. (formerly known as Arbinet Holdings, Inc., a Delaware corporation, the “Company”) having an office at 120 Albany Street, Suite 450, Tower II, New Brunswick, NJ 08901 and Alex Mashinsky, an individual currently residing at 495 West End Avenue, New York, NY 10024 (collectively, the “Parties”).

WHEREAS, Mr. Mashinsky is the founder of the Company and entered into those certain promissory notes dated April 15, 2000 and April 30, 2000 in favor of the Company and the Parties have agreed to amend the terms of these promissory notes (the “Loan Agreements”).

WHEREAS, Mr. Mashinsky entered into that certain Restated Employment Agreement dated December 2, 1999, as further amended on May 8, 2001, August 3, 2001, and August 8, 2001 (the “Employment Agreement”).

NOW THEREFORE, in consideration of the mutual covenants hereinafter contained, the Parties agree as follows:

contractor relationship, and all of the terms and conditions of this Agreement shall be interpreted in light of that relationship. Mr. Mashinsky agrees to furnish personal services as provided in this Agreement as an independent contractor using Mr. Mashinsky’s own means and methods. Mr. Mashinsky is engaged in an advisory capacity. There is no intention to create by this Agreement an employer-employee or agency relationship.

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out of any prior contractual obligations entered into by Mr. Mashinsky. Mr. Mashinsky represents and warrants that he has not made and will not make any contractual or other commitments that would conflict with or prevent his performance of any portion of this Agreement or conflict with the full enjoyment by the Company of the rights herein granted.

Following the termination of Mr. Mashinsky’s services under this Agreement, the Company will have no further liability to Mr. Mashinsky and no further payments will be made to Mr. Mashinsky, except: (i) the Company shall pay to Mr. Mashinsky (or, in the case of automatic termination upon Mr. Mashinsky’s death under subparagraph (a) above, to Mr. Mashinsky’s legal representatives or such named beneficiaries as Mr. Mashinsky may designate from time to time in a writing delivered to the Company) the pro rata portion of his monthly fee for the relevant calendar month through the date of termination, calculated by multiplying the Six Thousand Six Hundred Sixty-Six Dollar and Sixty-Seven Cents ($6,666.67) fee by a fraction, the numerator of which will be the number of days in the calendar month of termination prior to termination and the denominator of which shall be the number of days of that month; and (ii) to the extent Mr. Mashinsky is entitled to the reimbursement of business expenses incurred prior to termination as provided in Paragraph 5 above.

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confidential records, including without limitation (i) the software products, programs, applications and processes utilized by the Company (other than pre-packaged “off the shelf” products); (ii) the name and/or address of any customer or affiliate of the Company or any information concerning the transactions or relations of any customer, vendor or affiliates of the Company with the Company or any of its partners, principals, stockholders, directors, officers or agents; (iii) any information concerning any product, technology, or procedure employed by the Company but not generally known to its customers, vendors or competitors, or under development by or being tested by the Company but not at the time offered by the Company generally to customers or vendors; (iv) any information relating to the Company’s computer software, computer systems, pricing or marketing methods, sales margins, cost of goods, cost of material, capital structure, operating results, borrowing arrangements or business plans; (v) any information which is generally regarded as confidential or proprietary in any line of business engaged in by the Company; (vi) any business plans, budgets, advertising or marketing plans; (vii) any information contained in any of the Company’s written or oral policies and procedures or manuals; (viii) any information belonging to customers, vendors or affiliates of the Company or any other person or entity that the Company has agreed to hold in confidence; (ix) any inventions, innovations or improvements covered by this Agreement; and (x) all written, graphic and other material relating to any of the foregoing. Mr. Mashinsky acknowledges and understands that information that is not novel or copyrighted or patented may nonetheless be proprietary information. The term “proprietary information” shall not include information generally available to the public or information that is or becomes available to Mr. Mashinsky on a non-confidential basis from a source other than the Company or the Company’s directors, officers, employees, partners, principals or agents (other than as a result of a breach of any obligation of confidentiality). Immediately upon termination of Mr. Mashinsky’s services under this Agreement or at any other time upon the Company’s request, Mr. Mashinsky will return to the Company all personal property (including without limitation, all files, records, documents, lists, equipment, supplies, promotional materials, keys, phone or credit cards and similar items and all copies thereof or extracts therefrom) and

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confidential records of the Company. For purposes of this Agreement, “confidential records” means all correspondence, memoranda, files, manuals, books, lists, financial, operating or marketing records, magnetic tape, or electronic or other media or equipment of any kind.

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for or hold any ownership interest in any business in competition with any business conducted by the Company or its affiliates in any jurisdiction where the Company and/or its affiliates conduct such business as of the date of the termination of Mr. Mashinsky’s services hereunder (including, without limitation, any business activity or jurisdiction which is covered by or included in a written proposal or business plan existing as of the date of the termination of Mr. Mashinsky’s services hereunder). The above notwithstanding, it shall not be considered a violation of this subparagraph (d) if Mr. Mashinsky (i) owns, for investment purposes, up to one percent (1%) of the total outstanding equity securities of a publicly traded company, and/or (ii) performs services for any enterprise to the extent such services are not performed, directly or indirectly, for a business unit of the enterprise in competition with the Company and/or its affiliates.

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Mashinsky of any clause of this Paragraph 8 will cause the Company irreparable injury that cannot be adequately compensated by monetary damages alone. Therefore, Mr. Mashinsky agrees that the Company, without limiting any other legal or equitable remedies available to it, shall be entitled to obtain equitable relief by injunction or otherwise from any court of competent jurisdiction, including, without limitation, injunctive relief to prevent Mr. Mashinsky’s failure to comply with the terms and conditions of this Paragraph 8. The twelve (12) month periods referenced in subparagraphs (b), (c) and (d) above shall be extended on a day-for-day basis for each day during which Mr. Mashinsky violates the provisions of subparagraphs (b), (c) or (d) in any respect, so that Mr. Mashinsky is restricted from engaging in the activities prohibited by subparagraphs (b), (c) and (d) for the full twelve (12) month period.

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term of this Agreement and thereafter in the securing of trade name, trademark, patent or copyright protection or other similar rights in the United States and in foreign countries and shall give evidence and testimony and execute and deliver to the Company all papers requested by it in connection therewith.

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as such Party shall have specified by written notice to the other Party given in accordance with the terms of this Paragraph 17:

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IN WITNESS WHEREOF, this Agreement has been executed and delivered by the Parties as of the first date written above.

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