CHOICE ONE USES DSET TO PROVIDE GATEWAY FOR DSL CIRCUIT ELECTRONIC BONDING;

Electronic Bonding Solution from DSET to Enhance Choice One's Line Provisioning Speed and Accuracy.

Rochester, New York and Bridgewater, New Jersey - June 22, 2000 -- Choice One Communications (Nasdaq: CWON), an Integrated Communications Provider offering facilities-based voice and data telecommunications services to small and medium-sized businesses and DSET Corporation (Nasdaq: DSET), a leading supplier of business-to-business e-commerce connectivity solutions for the telecom industry, announced today that Choice One has achieved full electronic bonding with the Bell Atlantic North region for provisioning DSL circuits.

Through DSET's ezLocal gateway, Choice One is now able to automate the exchange of complex local service request (LSR) data between its DSL circuit provisioning center and the Bell Atlantic North region, the incumbent exchange carrier serving most of the Northeast United States. Choice One previously had achieved an electronic bonding solution with the carrier for voice circuit provisioning using DSET's gateway product. Adding DSL provisioning capability allows Choice One to order all the facilities needed to provision service efficiently and cost-effectively.

According to Kevin Dickens, senior vice president, operations and engineering of Choice One, "The DSET solution is an integral component of our order provisioning process via electronic bonding with the incumbent telephone company. This equates to improved client service across the board. We are now able to provision lines in under twelve hours with a seamless interface to the incumbent carrier."

Dickens added, "In addition to reducing the time required to effectively process orders, electronic bonding enables us to ensure greater accuracy by reducing the amount of data entry keying, and eliminating redundancy. We no longer need to input data into multiple systems and this ultimately enhances the efficiency and accuracy of our order provisioning process."

"We're especially pleased that Choice One is turned up for automated ordering of DSL loops using a DSET electronic-bonding solution," said Phil Cavallo, DSET's senior vice president of worldwide sales and marketing. "Increasingly, a critical aspect of Choice One's success will be the ability to order and provision DSL circuits. The demand for these high capacity access lines is very strong and growing rapidly which creates a substantial opportunity.

The combination of our ezLocal gateway and MetaSolv's Telecom Business Solution ™ (TBS ™) software enables Choice One to order and provision DSL loops faster and much more efficiently than other competing carriers. By implementing this system, Choice One Communications has demonstrated its commitment to providing the highest quality of service to its clients, which becomes a competitive advantage for Choice One."

About Choice One Communications:

Headquartered in Rochester, New York, Choice One (Nasdaq: CWON) is a leading integrated communications services provider offering local, long distance, high-speed data, Internet and DSL solutions, and web hosting and design, primarily to small and medium-sized businesses in second and third tier markets in the Northeast, U.S. In February, Choice One completed an Initial Public Offering for a total of $164 million of common stock at $20 per share.

Choice One currently serves customers in twelve markets throughout New York, Pennsylvania, Massachusetts, Rhode Island, and New Hampshire. The company plans to operate in Hartford and New Haven, Connecticut by this summer and in Akron, Dayton, and Columbus, Ohio by the end of the year. On May 15, Choice One announced a definitive agreement to merge with US XChange based in Grand Rapids, Michigan. Choice One's expanded territory as a direct result of this merger will include nine additional second and third tier markets in Michigan, Indiana, Wisconsin and Illinois.

For further information about Choice One, visit our web site at www.choiceonecom.com or contact us at 1-888-832-5800.

About DSET:

DSET Corporation (Nasdaq: DSET) is a leading provider of business-to-business e-commerce connectivity solutions for the global telecommunications marketplace. The DSET suite of electronic-bonding gateways is designed to interconnect the operations support systems (OSSs) of service providers that must exchange information and share network capabilities with trading partners to provision and maintain a growing range of services for customers in the competitive telecom market. DSET's local number portability solutions play a key role in enabling business and residential customers to change service providers without changing their local phone numbers. DSET is headquartered in Bridgewater, New Jersey, and the company's Web site can be viewed at www.dset.com.

Forward-Looking Statements

Certain statements contained in this press release constitute "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995, and the companies intend that such forward-looking statements be subject to the safe harbors created thereby. The words "believes", "expects", "estimates", "anticipates", "will be" and "plans" and similar words or expressions identify forward-looking statements made by or on behalf of the company. These forward-looking statements are subject to many uncertainties and factors that may cause the actual results of the company to be materially different from any future results expressed or implied by such forward-looking statements. Examples of such uncertainties and factors include, but are not limited to, availability of financing and regulatory approvals, the number of potential customers in a target market, the existence of strategic alliances or relationships, technological, regulatory or other developments in the company's business, changes in the competitive climate in which the company operates and the emergence of future opportunities, all of which could cause actual results and experiences to differ materially from anticipated results and expectations expressed in the forward-looking statements contained herein. These and other applicable risks are summarized under the caption "Risk Factors" and elsewhere in the companies' Registration Statement on Form S-1, Registration No. 333-91321, filed with the Securities and Exchange Commission and declared effective on February 16, 2000.

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Choice One contact:
Ythan A. Lax
Director, Corporate Communications
716-530-2944
ylax@choiceonecom.com

DSET contact:
Dean Maskevich
DSET Marketing Communications
908-526-7500, ext. 1366
dmaskevi@dset.com