Online
“Established in 1997 by Telstra a global leader in telecommunications, now Online is locally owned and managed. Online is the largest and most technologically advanced Internet Service Provider (ISP) in Cambodia.”
http://www.online.com.kh

City Link
“City Link is Cambodia's largest Internet Service Provider. With our advance technical expertise for a great internet experience and relax in the knowledge that is ISP is here to stay. Our internet access network are vast and fast. You can get stabilize connection, fastest speed and effective price. In fact, we could probably offers you many options need with data planes and your budget. Our products offers straight forward Internet VISA card, Dial Up post paid, ADSL@home, Acad-ADSL@home, ADSL Unlimited, ADSL Plus, Lease Line, VPN, and Hosting Services.”
http://www.citylink.com.kh