This is a US Robotics 56K Performance Pro Modem. The model number is 5610C. The US Robotics 56K Performance Pro Modem combines controller-based performance with the advantages of V.92 technology. The Modem On Hold call management feature identifies?incoming calls, and enables you to take the call?without losing?your internet connection. Get online faster and reach speeds up to 48 Kbps upstream and 53 Kbps downstream. This modem is software upgradable and supports both Linux and Windows operating systems.