

	iBasis Announces Filings for Common Stock and Convertible Subordinated Note Offerings Burlington, Mass.-February 10, 2000-iBasis, Inc., (Nasdaq: IBAS) today announced that it has filed separate registration statements with the Securities and Exchange Commission for proposed concurrent offerings of Common Stock and Convertible Subordinated Notes due 2005. An aggregate of 3,500,000 shares of the company's Common Stock will be offered in the common stock offering, of which 2,000,000 shares will be offered by the company and 1,500,000 shares will be offered by selling stockholders. The company will not receive any proceeds from the sale of shares by the selling stockholders. In addition, the underwriters of the common stock offering will be granted a 30-day option to purchase up to an aggregate of 525,000 additional shares of Common Stock from certain selling stockholders and the company to cover over-allotments, if any. An aggregate of $150,000,000 principal amount of Convertible Subordinated Notes due 2005 will be offered in the convertible subordinated note offering. The Notes will be convertible into shares of the company's Common Stock at a conversion price to be determined. In addition, the underwriters of the convertible subordinated note offering will be granted a 30-day option to purchase up to an aggregate of $22,500,000 principal amount of Notes. The price to the public of the Common Stock and of the Convertible Subordinated Notes due 2005 has not been determined. The offerings will be lead managed by FleetBoston Robertson Stephens Inc. and the co-managers will include Chase Securities Inc., U.S. Bancorp Piper Jaffray Inc. and Dain Rauscher Incorporated. Copies of the preliminary prospectuses relating to the offerings and meeting the requirements of the Securities Act of 1933 may be obtained from FleetBoston Robertson Stephens Inc., 555 California Street, Suite 2600, San Francisco, CA 94104, tel.: 415-781-9700, fax: 415-248-4042; Chase Securities Inc., One Bush Street, San Francisco, CA 94104, tel.: 415-439-3000, fax: 415-439-3624; U.S. Bancorp Piper Jaffray Inc., 222 South Ninth Street, Minneapolis, MN 55402, tel.: 612-342-6000, fax: 612-342-1037; and Dain Rauscher Incorporated, 60 South Sixth Street, Minneapolis, MN 55402, tel.: 612-371-2818, fax: 612-371-2837. A Registration Statement relating to these securities has been filed with the Securities and Exchange Commission but has not yet become effective. These securities may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective. This press release shall not constitute an offer to sell nor the solicitation of an offer to buy, nor shall there be any sale of these securities in any State in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such State. Except for historical information, all of the expectations, projections and assumptions contained in the foregoing press release constitute forward-looking statements under the Private Securities Litigation Reform Act of 1995 and involve risks and uncertainties. Important factors that could cause actual results to differ materially from such forward-looking statements include, but are not limited to, the considerations described as "Risk Factors" in iBasis' preliminary prospectuses dated February 10, 2000, and the company's other SEC filings About iBasis Founded in 1996, iBasis (Nasdaq: IBAS) is the leader in advanced Internet-based communications. iBasis uniquely combines a superior technology platform, premium Internet bandwidth and proprietary Assured Quality Routing™ (AQR) software to deliver advanced, Internet-based communications services to tier one carriers and other service providers. The iBasis Network™, a global, high-capacity Internet communications network, is the world's largest international Cisco Powered Network™ for Internet Telephony. The company can be reached at its worldwide headquarters in Burlington, Mass. at 781-505-7500 or on the Internet at www.ibasis.net. ### iBasis, The iBasis Network and Assured Quality Routing are registered trademarks of iBasis, Inc. Cisco and Cisco Powered Network are registered trademarks of Cisco Systems, Inc.