CAIS Internet's OverVoice Chosen by Teledex Corporation as a High Speed Internet Access Feature in Up to 3.4 Million Desktop Telephones Worldwide.

WASHINGTON--(BUSINESS WIRE)--June 21, 1999--

Leader in Delivering Multi-Point Internet Distribution for Hotels and

Leader in Telephone Equipment for Hotels Announce Agreement

CAIS Internet (NASDAQ: CAIS) announced today that the leading provider of hotel in-room guest telephones, Teledex Corporation, will support CAIS Internet's OverVoice technology in Teledex's new TeamNet telephone products -- marking the growing selection of CAIS's OverVoice technology for high speed Internet applications for hotels.

The agreement has the potential to expand the availability of CAIS Internet's OverVoice for up to 3.4 million telephones that Teledex has shipped worldwide. Teledex Corporation will introduce at HITEC the new TeamNet high speed Internet support accessory that attaches underneath Teledex's Diamond, Millennium and Opal telephones. TeamNet is the only solution that allows the hotelier to upgrade their guest room telephone to support the new high speed Internet connectivity options using a hotel's existing wiring.

"OverVoice is a natural choice because of its compact patented technology that delivers high speed Internet access using existing wires, just like TeamNet products," said Ron Lesniak, President of Teledex Corporation. "CAIS Internet's OverVoice in guest rooms is a benefit for business travelers, and a simple solution for hotels installing high speed Internet access."

CAIS Internet -- the supplier of OverVoice patented technology that enables multi-point distribution of high speed Internet up to 10 Mbps - will work with Teledex to manufacture the CAIS OverVoice devices under CAIS's standards and include them in Teledex's TeamNet telephones.

"We're pleased to expand the reach of OverVoice in hotels with Teledex Corporation's TeamNet products," said Ulysses G. Auger II, CEO, CAIS Internet. "Their equipment and our technology will take another great stride in delivering high speed Internet access to the business traveler."

About Teledex Corporation

Founded in 1985, Teledex is recognized as one of the fastest growing private companies in San Jose/Silicon Valley. This growth has established Teledex as the worldwide leader in providing high quality and durable guestroom telecommunications products to the hospitality industry. Teledex's products are approved for use throughout the world and have been selected as a preferred product by most major hotel chains as well as a number of multi-national corporations. Headquartered in San Jose, California, Teledex maintains business offices throughout the United States as well as in Peru, United Kingdom, Beijing, Hong Kong and Singapore. Teledex Corporation is a full service organization which designs, manufactures and markets a full range of communications products addressing the hospitality, corporate and consumer markets. Additional information on Teledex can be found at www.teledex.com.

About OverVoice by CAIS Internet

OverVoice technology is a cost-effective and sensible solution to existing multi-dwelling unit infrastructures and makes properties Internet-ready at speeds up to 175 times faster than 56K dial-up connections. OverVoice technology is simply installed on top of the property's existing telephone system while creating an Ethernet local area network that can transmit data traffic up to 10 Mbps. OverVoice provides users an uninterrupted, dedicated high speed Internet connection that can be shared simultaneously among many users in a hotel.

About CAIS Internet

CAIS Internet is a leading provider of the latest in broadband Internet access for consumers and businesses using advanced technologies like CAIS HyperDSL, patented solutions like OverVoice(R), as well as expert technical and customer support. CAIS HyperDSL, the latest in DSL Internet technology, delivers dedicated, cost-effective high speed Internet access to businesses and consumers.

CAIS Internet operates a nationwide, clear-channel DS3/OC3 and ATM Network with POPs (points of presence) in Chicago, IL, Washington, DC, Baltimore, MD, McLean, VA, San Francisco, CA, and has plans for POPs in Dallas, TX, Philadelphia, PA, Los Angeles, CA, Seattle, WA, Boston, MA, Atlanta, GA, and Miami, FL. CAIS's backbone is a Cisco-Powered Network, and currently peers with public and private partners, and at national exchange points, MAE East, MAE East ATM, MAE West, and AADS.

CAIS Internet is headquartered in Washington, DC. For more information, you may contact the company at 888.260.CAIS, or visit the website at www.cais.com.

This release contains statements relating to CAIS's future expectations and business strategies or other "forward-looking" information. Those statements are subject to known and unknown risks, uncertainties and other factors that could cause actual results to differ materially from those contemplated by the statements. Important factors that may cause actual results to differ from projections include, among others: changes in business conditions; changes in the Internet services industry and the general economy; our limited operating history; our ability to manage rapid growth; our ability to enter into joint ventures and other strategic relationships with companies on terms acceptable to us; and the impact of computer and related problems that may arise from the Year 2000 problem on our business.