WASHINGTON, D.C., July 11, 2005 - Cogent Communications Group, Inc. (AMEX: COI), a multinational Tier 1 Internet service provider, announced today that it has added several new On-Net markets in North America and Europe where it can offer its high-quality IP Ethernet service to customers via direct connections to Cogent's optical network. Markets include Baltimore, Cleveland, Portland and St. Louis in the United States. And in Europe the markets include Copenhagen (Denmark), Nuremberg (Germany), Vienna (Austria), Vigo (Spain) and Porto (Portugal). Cogent now offers its full suite of On-Net services in these markets, including Internet transit (10 - multiple 1,000 Megabits per second [Mbps]) and Layer 2 Point-to-Point connectivity (100 – multiple 1000 Mbps).

Cogent typically selects new On-Net markets based on the size of the market, concentration of businesses, dark fiber availability and location. "We identified these cities for On-Net services based on bandwidth demand and repeated inquiries from prospects located in these markets," said Dave Schaeffer, CEO of Cogent Communications. "While Cogent remains focused on increasing revenue in existing markets, these locations represent strategic opportunities to expand service to new geographic areas."

In addition, Cogent also announced a major expansion and diversification of its transatlantic capacity. The additional capacity provides more bandwidth to meet growing customer demand for Cogent's services. The additional diversity resulting from three completely independent transatlantic routes from three different suppliers adds an increased layer of reliability to Cogent's already robust network performance. With the addition of the new capacity, Cogent's transatlantic capacity now includes an OC-192 (10 Gigabits) between New York and Madrid, an OC-192 between Boston and London, and OC-48 (2.488 Gigabits) between Washington, D.C. and Frankfurt.

"Thanks to growth in traffic from both new customers and existing customers, as well as our broad set of peering connections in both North America and Europe, Cogent's transatlantic internet traffic is growing rapidly," said Reed Harrison, President and Chief Operating Officer of Cogent Communications. "While we are announcing today that we now have 22.5 Gigabits per second of transatlantic capacity, we are already in active discussions with potential suppliers about further success-based capacity expansions needed for the traffic growth trajectory we are seeing between our networks in North America and Europe."

About Cogent Communications:

Cogent Communications (AMEX: COI) is the number one provider of Ethernet services in the United States as ranked by Ovum-RHK and is one of the fastest growing Tier 1 ISPs in the world. Its facilities based, all-optical network delivers ultra-high speed Internet access and transport services to businesses and service providers in major metropolitan areas. Cogent offers services across its 30,600-mile IP network spanning 12 countries located in North America and Europe.

The combination of technology, IP network architecture and unique business model has combined to help make Cogent one of the most popular solutions for reliable, cost-effective Internet service in the industry.

Cogent offers several focused services that complement its On-Net Internet access service including dedicated Off-Net (T1, T3) Internet service, colocation services in 30 colocation facilities across North America and Europe, and Layer 2 Point-to-Point services in every On-Net market.

Cogent Communications is headquartered at 1015 31st Street, NW, Washington, D.C. 20007. For more information, visit www.cogentco.com. Cogent Communications can be reached in the United States at (202) 295-4200 or via email at Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser..

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Information in this release may involve expectations, beliefs, plans, intentions or strategies regarding the future. These forward-looking statements involve risks and uncertainties. All forward-looking statements included in this release are based upon information available to Cogent Communications Group, Inc. as of the date of the release, and we assume no obligation to update any such forward-looking statement. The statements in this release are not guarantees of future performance and actual results could differ materially from our current expectations. Numerous factors could cause or contribute to such differences. Some of the factors and risks associated with our business are discussed in Cogent's registration statements filed with the Securities and Exchange Commission and in its other reports filed from time to time with the SEC.

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